/* * Copyright (c) 1997, 2014, Oracle and/or its affiliates. All rights reserved. * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. * * This code is free software; you can redistribute it and/or modify it * under the terms of the GNU General Public License version 2 only, as * published by the Free Software Foundation. * * This code is distributed in the hope that it will be useful, but WITHOUT * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License * version 2 for more details (a copy is included in the LICENSE file that * accompanied this code). * * You should have received a copy of the GNU General Public License version * 2 along with this work; if not, write to the Free Software Foundation, * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. * * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA * or visit www.oracle.com if you need additional information or have any * questions. * */ #include "precompiled.hpp" #include "classfile/classLoader.hpp" #include "classfile/javaClasses.hpp" #include "classfile/systemDictionary.hpp" #include "classfile/vmSymbols.hpp" #include "code/scopeDesc.hpp" #include "compiler/compileBroker.hpp" #include "interpreter/interpreter.hpp" #include "interpreter/linkResolver.hpp" #include "interpreter/oopMapCache.hpp" #include "jvmtifiles/jvmtiEnv.hpp" #include "memory/gcLocker.inline.hpp" #include "memory/metaspaceShared.hpp" #include "memory/oopFactory.hpp" #include "memory/universe.inline.hpp" #include "oops/instanceKlass.hpp" #include "oops/objArrayOop.hpp" #include "oops/oop.inline.hpp" #include "oops/symbol.hpp" #include "prims/jvm_misc.hpp" #include "prims/jvmtiExport.hpp" #include "prims/jvmtiThreadState.hpp" #include "prims/privilegedStack.hpp" #include "runtime/arguments.hpp" #include "runtime/biasedLocking.hpp" #include "runtime/deoptimization.hpp" #include "runtime/fprofiler.hpp" #include "runtime/frame.inline.hpp" #include "runtime/init.hpp" #include "runtime/interfaceSupport.hpp" #include "runtime/java.hpp" #include "runtime/javaCalls.hpp" #include "runtime/jniPeriodicChecker.hpp" #include "runtime/memprofiler.hpp" #include "runtime/mutexLocker.hpp" #include "runtime/objectMonitor.hpp" #include "runtime/orderAccess.inline.hpp" #include "runtime/osThread.hpp" #include "runtime/safepoint.hpp" #include "runtime/sharedRuntime.hpp" #include "runtime/statSampler.hpp" #include "runtime/stubRoutines.hpp" #include "runtime/task.hpp" #include "runtime/thread.inline.hpp" #include "runtime/threadCritical.hpp" #include "runtime/threadLocalStorage.hpp" #include "runtime/vframe.hpp" #include "runtime/vframeArray.hpp" #include "runtime/vframe_hp.hpp" #include "runtime/vmThread.hpp" #include "runtime/vm_operations.hpp" #include "services/attachListener.hpp" #include "services/management.hpp" #include "services/memTracker.hpp" #include "services/threadService.hpp" #include "trace/tracing.hpp" #include "trace/traceMacros.hpp" #include "utilities/defaultStream.hpp" #include "utilities/dtrace.hpp" #include "utilities/events.hpp" #include "utilities/preserveException.hpp" #include "utilities/macros.hpp" #ifdef TARGET_OS_FAMILY_linux # include "os_linux.inline.hpp" #endif #ifdef TARGET_OS_FAMILY_solaris # include "os_solaris.inline.hpp" #endif #ifdef TARGET_OS_FAMILY_windows # include "os_windows.inline.hpp" #endif #ifdef TARGET_OS_FAMILY_bsd # include "os_bsd.inline.hpp" #endif #if INCLUDE_ALL_GCS #include "gc_implementation/concurrentMarkSweep/concurrentMarkSweepThread.hpp" #include "gc_implementation/g1/concurrentMarkThread.inline.hpp" #include "gc_implementation/parallelScavenge/pcTasks.hpp" #endif // INCLUDE_ALL_GCS #ifdef COMPILER1 #include "c1/c1_Compiler.hpp" #endif #ifdef COMPILER2 #include "opto/c2compiler.hpp" #include "opto/idealGraphPrinter.hpp" #endif #if INCLUDE_RTM_OPT #include "runtime/rtmLocking.hpp" #endif PRAGMA_FORMAT_MUTE_WARNINGS_FOR_GCC #ifdef DTRACE_ENABLED // Only bother with this argument setup if dtrace is available #ifndef USDT2 HS_DTRACE_PROBE_DECL(hotspot, vm__init__begin); HS_DTRACE_PROBE_DECL(hotspot, vm__init__end); HS_DTRACE_PROBE_DECL5(hotspot, thread__start, char*, intptr_t, intptr_t, intptr_t, bool); HS_DTRACE_PROBE_DECL5(hotspot, thread__stop, char*, intptr_t, intptr_t, intptr_t, bool); #define DTRACE_THREAD_PROBE(probe, javathread) \ { \ ResourceMark rm(this); \ int len = 0; \ const char* name = (javathread)->get_thread_name(); \ len = strlen(name); \ HS_DTRACE_PROBE5(hotspot, thread__##probe, \ name, len, \ java_lang_Thread::thread_id((javathread)->threadObj()), \ (javathread)->osthread()->thread_id(), \ java_lang_Thread::is_daemon((javathread)->threadObj())); \ } #else /* USDT2 */ #define HOTSPOT_THREAD_PROBE_start HOTSPOT_THREAD_PROBE_START #define HOTSPOT_THREAD_PROBE_stop HOTSPOT_THREAD_PROBE_STOP #define DTRACE_THREAD_PROBE(probe, javathread) \ { \ ResourceMark rm(this); \ int len = 0; \ const char* name = (javathread)->get_thread_name(); \ len = strlen(name); \ HOTSPOT_THREAD_PROBE_##probe( /* probe = start, stop */ \ (char *) name, len, \ java_lang_Thread::thread_id((javathread)->threadObj()), \ (uintptr_t) (javathread)->osthread()->thread_id(), \ java_lang_Thread::is_daemon((javathread)->threadObj())); \ } #endif /* USDT2 */ #else // ndef DTRACE_ENABLED #define DTRACE_THREAD_PROBE(probe, javathread) #endif // ndef DTRACE_ENABLED // Class hierarchy // - Thread // - VMThread // - WatcherThread // - ConcurrentMarkSweepThread // - JavaThread // - CompilerThread // ======= Thread ======== // Support for forcing alignment of thread objects for biased locking void* Thread::allocate(size_t size, bool throw_excpt, MEMFLAGS flags) { if (UseBiasedLocking) { const int alignment = markOopDesc::biased_lock_alignment; size_t aligned_size = size + (alignment - sizeof(intptr_t)); void* real_malloc_addr = throw_excpt? AllocateHeap(aligned_size, flags, CURRENT_PC) : AllocateHeap(aligned_size, flags, CURRENT_PC, AllocFailStrategy::RETURN_NULL); void* aligned_addr = (void*) align_size_up((intptr_t) real_malloc_addr, alignment); assert(((uintptr_t) aligned_addr + (uintptr_t) size) <= ((uintptr_t) real_malloc_addr + (uintptr_t) aligned_size), "JavaThread alignment code overflowed allocated storage"); if (TraceBiasedLocking) { if (aligned_addr != real_malloc_addr) tty->print_cr("Aligned thread " INTPTR_FORMAT " to " INTPTR_FORMAT, real_malloc_addr, aligned_addr); } ((Thread*) aligned_addr)->_real_malloc_address = real_malloc_addr; return aligned_addr; } else { return throw_excpt? AllocateHeap(size, flags, CURRENT_PC) : AllocateHeap(size, flags, CURRENT_PC, AllocFailStrategy::RETURN_NULL); } } void Thread::operator delete(void* p) { if (UseBiasedLocking) { void* real_malloc_addr = ((Thread*) p)->_real_malloc_address; FreeHeap(real_malloc_addr, mtThread); } else { FreeHeap(p, mtThread); } } // Base class for all threads: VMThread, WatcherThread, ConcurrentMarkSweepThread, // JavaThread Thread::Thread() { // stack and get_thread set_stack_base(NULL); set_stack_size(0); set_self_raw_id(0); set_lgrp_id(-1); // allocated data structures set_osthread(NULL); set_resource_area(new (mtThread)ResourceArea()); DEBUG_ONLY(_current_resource_mark = NULL;) set_handle_area(new (mtThread) HandleArea(NULL)); set_metadata_handles(new (ResourceObj::C_HEAP, mtClass) GrowableArray(30, true)); set_active_handles(NULL); set_free_handle_block(NULL); set_last_handle_mark(NULL); // This initial value ==> never claimed. _oops_do_parity = 0; _metadata_on_stack_buffer = NULL; // the handle mark links itself to last_handle_mark new HandleMark(this); // plain initialization debug_only(_owned_locks = NULL;) debug_only(_allow_allocation_count = 0;) NOT_PRODUCT(_allow_safepoint_count = 0;) NOT_PRODUCT(_skip_gcalot = false;) _jvmti_env_iteration_count = 0; set_allocated_bytes(0); _vm_operation_started_count = 0; _vm_operation_completed_count = 0; _current_pending_monitor = NULL; _current_pending_monitor_is_from_java = true; _current_waiting_monitor = NULL; _num_nested_signal = 0; omFreeList = NULL ; omFreeCount = 0 ; omFreeProvision = 32 ; omInUseList = NULL ; omInUseCount = 0 ; #ifdef ASSERT _visited_for_critical_count = false; #endif _SR_lock = new Monitor(Mutex::suspend_resume, "SR_lock", true); _suspend_flags = 0; // thread-specific hashCode stream generator state - Marsaglia shift-xor form _hashStateX = os::random() ; _hashStateY = 842502087 ; _hashStateZ = 0x8767 ; // (int)(3579807591LL & 0xffff) ; _hashStateW = 273326509 ; _OnTrap = 0 ; _schedctl = NULL ; _Stalled = 0 ; _TypeTag = 0x2BAD ; // Many of the following fields are effectively final - immutable // Note that nascent threads can't use the Native Monitor-Mutex // construct until the _MutexEvent is initialized ... // CONSIDER: instead of using a fixed set of purpose-dedicated ParkEvents // we might instead use a stack of ParkEvents that we could provision on-demand. // The stack would act as a cache to avoid calls to ParkEvent::Allocate() // and ::Release() _ParkEvent = ParkEvent::Allocate (this) ; _SleepEvent = ParkEvent::Allocate (this) ; _MutexEvent = ParkEvent::Allocate (this) ; _MuxEvent = ParkEvent::Allocate (this) ; #ifdef CHECK_UNHANDLED_OOPS if (CheckUnhandledOops) { _unhandled_oops = new UnhandledOops(this); } #endif // CHECK_UNHANDLED_OOPS #ifdef ASSERT if (UseBiasedLocking) { assert((((uintptr_t) this) & (markOopDesc::biased_lock_alignment - 1)) == 0, "forced alignment of thread object failed"); assert(this == _real_malloc_address || this == (void*) align_size_up((intptr_t) _real_malloc_address, markOopDesc::biased_lock_alignment), "bug in forced alignment of thread objects"); } #endif /* ASSERT */ } void Thread::initialize_thread_local_storage() { // Note: Make sure this method only calls // non-blocking operations. Otherwise, it might not work // with the thread-startup/safepoint interaction. // During Java thread startup, safepoint code should allow this // method to complete because it may need to allocate memory to // store information for the new thread. // initialize structure dependent on thread local storage ThreadLocalStorage::set_thread(this); } void Thread::record_stack_base_and_size() { set_stack_base(os::current_stack_base()); set_stack_size(os::current_stack_size()); if (is_Java_thread()) { ((JavaThread*) this)->set_stack_overflow_limit(); } // CR 7190089: on Solaris, primordial thread's stack is adjusted // in initialize_thread(). Without the adjustment, stack size is // incorrect if stack is set to unlimited (ulimit -s unlimited). // So far, only Solaris has real implementation of initialize_thread(). // // set up any platform-specific state. os::initialize_thread(this); #if INCLUDE_NMT // record thread's native stack, stack grows downward address stack_low_addr = stack_base() - stack_size(); MemTracker::record_thread_stack(stack_low_addr, stack_size()); #endif // INCLUDE_NMT } Thread::~Thread() { // Reclaim the objectmonitors from the omFreeList of the moribund thread. ObjectSynchronizer::omFlush (this) ; EVENT_THREAD_DESTRUCT(this); // stack_base can be NULL if the thread is never started or exited before // record_stack_base_and_size called. Although, we would like to ensure // that all started threads do call record_stack_base_and_size(), there is // not proper way to enforce that. #if INCLUDE_NMT if (_stack_base != NULL) { address low_stack_addr = stack_base() - stack_size(); MemTracker::release_thread_stack(low_stack_addr, stack_size()); #ifdef ASSERT set_stack_base(NULL); #endif } #endif // INCLUDE_NMT // deallocate data structures delete resource_area(); // since the handle marks are using the handle area, we have to deallocated the root // handle mark before deallocating the thread's handle area, assert(last_handle_mark() != NULL, "check we have an element"); delete last_handle_mark(); assert(last_handle_mark() == NULL, "check we have reached the end"); // It's possible we can encounter a null _ParkEvent, etc., in stillborn threads. // We NULL out the fields for good hygiene. ParkEvent::Release (_ParkEvent) ; _ParkEvent = NULL ; ParkEvent::Release (_SleepEvent) ; _SleepEvent = NULL ; ParkEvent::Release (_MutexEvent) ; _MutexEvent = NULL ; ParkEvent::Release (_MuxEvent) ; _MuxEvent = NULL ; delete handle_area(); delete metadata_handles(); // osthread() can be NULL, if creation of thread failed. if (osthread() != NULL) os::free_thread(osthread()); delete _SR_lock; // clear thread local storage if the Thread is deleting itself if (this == Thread::current()) { ThreadLocalStorage::set_thread(NULL); } else { // In the case where we're not the current thread, invalidate all the // caches in case some code tries to get the current thread or the // thread that was destroyed, and gets stale information. ThreadLocalStorage::invalidate_all(); } CHECK_UNHANDLED_OOPS_ONLY(if (CheckUnhandledOops) delete unhandled_oops();) } // NOTE: dummy function for assertion purpose. void Thread::run() { ShouldNotReachHere(); } #ifdef ASSERT // Private method to check for dangling thread pointer void check_for_dangling_thread_pointer(Thread *thread) { assert(!thread->is_Java_thread() || Thread::current() == thread || Threads_lock->owned_by_self(), "possibility of dangling Thread pointer"); } #endif #ifndef PRODUCT // Tracing method for basic thread operations void Thread::trace(const char* msg, const Thread* const thread) { if (!TraceThreadEvents) return; ResourceMark rm; ThreadCritical tc; const char *name = "non-Java thread"; int prio = -1; if (thread->is_Java_thread() && !thread->is_Compiler_thread()) { // The Threads_lock must be held to get information about // this thread but may not be in some situations when // tracing thread events. bool release_Threads_lock = false; if (!Threads_lock->owned_by_self()) { Threads_lock->lock(); release_Threads_lock = true; } JavaThread* jt = (JavaThread *)thread; name = (char *)jt->get_thread_name(); oop thread_oop = jt->threadObj(); if (thread_oop != NULL) { prio = java_lang_Thread::priority(thread_oop); } if (release_Threads_lock) { Threads_lock->unlock(); } } tty->print_cr("Thread::%s " INTPTR_FORMAT " [%lx] %s (prio: %d)", msg, thread, thread->osthread()->thread_id(), name, prio); } #endif ThreadPriority Thread::get_priority(const Thread* const thread) { trace("get priority", thread); ThreadPriority priority; // Can return an error! (void)os::get_priority(thread, priority); assert(MinPriority <= priority && priority <= MaxPriority, "non-Java priority found"); return priority; } void Thread::set_priority(Thread* thread, ThreadPriority priority) { trace("set priority", thread); debug_only(check_for_dangling_thread_pointer(thread);) // Can return an error! (void)os::set_priority(thread, priority); } void Thread::start(Thread* thread) { trace("start", thread); // Start is different from resume in that its safety is guaranteed by context or // being called from a Java method synchronized on the Thread object. if (!DisableStartThread) { if (thread->is_Java_thread()) { // Initialize the thread state to RUNNABLE before starting this thread. // Can not set it after the thread started because we do not know the // exact thread state at that time. It could be in MONITOR_WAIT or // in SLEEPING or some other state. java_lang_Thread::set_thread_status(((JavaThread*)thread)->threadObj(), java_lang_Thread::RUNNABLE); } os::start_thread(thread); } } // Enqueue a VM_Operation to do the job for us - sometime later void Thread::send_async_exception(oop java_thread, oop java_throwable) { VM_ThreadStop* vm_stop = new VM_ThreadStop(java_thread, java_throwable); VMThread::execute(vm_stop); } // // Check if an external suspend request has completed (or has been // cancelled). Returns true if the thread is externally suspended and // false otherwise. // // The bits parameter returns information about the code path through // the routine. Useful for debugging: // // set in is_ext_suspend_completed(): // 0x00000001 - routine was entered // 0x00000010 - routine return false at end // 0x00000100 - thread exited (return false) // 0x00000200 - suspend request cancelled (return false) // 0x00000400 - thread suspended (return true) // 0x00001000 - thread is in a suspend equivalent state (return true) // 0x00002000 - thread is native and walkable (return true) // 0x00004000 - thread is native_trans and walkable (needed retry) // // set in wait_for_ext_suspend_completion(): // 0x00010000 - routine was entered // 0x00020000 - suspend request cancelled before loop (return false) // 0x00040000 - thread suspended before loop (return true) // 0x00080000 - suspend request cancelled in loop (return false) // 0x00100000 - thread suspended in loop (return true) // 0x00200000 - suspend not completed during retry loop (return false) // // Helper class for tracing suspend wait debug bits. // // 0x00000100 indicates that the target thread exited before it could // self-suspend which is not a wait failure. 0x00000200, 0x00020000 and // 0x00080000 each indicate a cancelled suspend request so they don't // count as wait failures either. #define DEBUG_FALSE_BITS (0x00000010 | 0x00200000) class TraceSuspendDebugBits : public StackObj { private: JavaThread * jt; bool is_wait; bool called_by_wait; // meaningful when !is_wait uint32_t * bits; public: TraceSuspendDebugBits(JavaThread *_jt, bool _is_wait, bool _called_by_wait, uint32_t *_bits) { jt = _jt; is_wait = _is_wait; called_by_wait = _called_by_wait; bits = _bits; } ~TraceSuspendDebugBits() { if (!is_wait) { #if 1 // By default, don't trace bits for is_ext_suspend_completed() calls. // That trace is very chatty. return; #else if (!called_by_wait) { // If tracing for is_ext_suspend_completed() is enabled, then only // trace calls to it from wait_for_ext_suspend_completion() return; } #endif } if (AssertOnSuspendWaitFailure || TraceSuspendWaitFailures) { if (bits != NULL && (*bits & DEBUG_FALSE_BITS) != 0) { MutexLocker ml(Threads_lock); // needed for get_thread_name() ResourceMark rm; tty->print_cr( "Failed wait_for_ext_suspend_completion(thread=%s, debug_bits=%x)", jt->get_thread_name(), *bits); guarantee(!AssertOnSuspendWaitFailure, "external suspend wait failed"); } } } }; #undef DEBUG_FALSE_BITS bool JavaThread::is_ext_suspend_completed(bool called_by_wait, int delay, uint32_t *bits) { TraceSuspendDebugBits tsdb(this, false /* !is_wait */, called_by_wait, bits); bool did_trans_retry = false; // only do thread_in_native_trans retry once bool do_trans_retry; // flag to force the retry *bits |= 0x00000001; do { do_trans_retry = false; if (is_exiting()) { // Thread is in the process of exiting. This is always checked // first to reduce the risk of dereferencing a freed JavaThread. *bits |= 0x00000100; return false; } if (!is_external_suspend()) { // Suspend request is cancelled. This is always checked before // is_ext_suspended() to reduce the risk of a rogue resume // confusing the thread that made the suspend request. *bits |= 0x00000200; return false; } if (is_ext_suspended()) { // thread is suspended *bits |= 0x00000400; return true; } // Now that we no longer do hard suspends of threads running // native code, the target thread can be changing thread state // while we are in this routine: // // _thread_in_native -> _thread_in_native_trans -> _thread_blocked // // We save a copy of the thread state as observed at this moment // and make our decision about suspend completeness based on the // copy. This closes the race where the thread state is seen as // _thread_in_native_trans in the if-thread_blocked check, but is // seen as _thread_blocked in if-thread_in_native_trans check. JavaThreadState save_state = thread_state(); if (save_state == _thread_blocked && is_suspend_equivalent()) { // If the thread's state is _thread_blocked and this blocking // condition is known to be equivalent to a suspend, then we can // consider the thread to be externally suspended. This means that // the code that sets _thread_blocked has been modified to do // self-suspension if the blocking condition releases. We also // used to check for CONDVAR_WAIT here, but that is now covered by // the _thread_blocked with self-suspension check. // // Return true since we wouldn't be here unless there was still an // external suspend request. *bits |= 0x00001000; return true; } else if (save_state == _thread_in_native && frame_anchor()->walkable()) { // Threads running native code will self-suspend on native==>VM/Java // transitions. If its stack is walkable (should always be the case // unless this function is called before the actual java_suspend() // call), then the wait is done. *bits |= 0x00002000; return true; } else if (!called_by_wait && !did_trans_retry && save_state == _thread_in_native_trans && frame_anchor()->walkable()) { // The thread is transitioning from thread_in_native to another // thread state. check_safepoint_and_suspend_for_native_trans() // will force the thread to self-suspend. If it hasn't gotten // there yet we may have caught the thread in-between the native // code check above and the self-suspend. Lucky us. If we were // called by wait_for_ext_suspend_completion(), then it // will be doing the retries so we don't have to. // // Since we use the saved thread state in the if-statement above, // there is a chance that the thread has already transitioned to // _thread_blocked by the time we get here. In that case, we will // make a single unnecessary pass through the logic below. This // doesn't hurt anything since we still do the trans retry. *bits |= 0x00004000; // Once the thread leaves thread_in_native_trans for another // thread state, we break out of this retry loop. We shouldn't // need this flag to prevent us from getting back here, but // sometimes paranoia is good. did_trans_retry = true; // We wait for the thread to transition to a more usable state. for (int i = 1; i <= SuspendRetryCount; i++) { // We used to do an "os::yield_all(i)" call here with the intention // that yielding would increase on each retry. However, the parameter // is ignored on Linux which means the yield didn't scale up. Waiting // on the SR_lock below provides a much more predictable scale up for // the delay. It also provides a simple/direct point to check for any // safepoint requests from the VMThread // temporarily drops SR_lock while doing wait with safepoint check // (if we're a JavaThread - the WatcherThread can also call this) // and increase delay with each retry SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay); // check the actual thread state instead of what we saved above if (thread_state() != _thread_in_native_trans) { // the thread has transitioned to another thread state so // try all the checks (except this one) one more time. do_trans_retry = true; break; } } // end retry loop } } while (do_trans_retry); *bits |= 0x00000010; return false; } // // Wait for an external suspend request to complete (or be cancelled). // Returns true if the thread is externally suspended and false otherwise. // bool JavaThread::wait_for_ext_suspend_completion(int retries, int delay, uint32_t *bits) { TraceSuspendDebugBits tsdb(this, true /* is_wait */, false /* !called_by_wait */, bits); // local flag copies to minimize SR_lock hold time bool is_suspended; bool pending; uint32_t reset_bits; // set a marker so is_ext_suspend_completed() knows we are the caller *bits |= 0x00010000; // We use reset_bits to reinitialize the bits value at the top of // each retry loop. This allows the caller to make use of any // unused bits for their own marking purposes. reset_bits = *bits; { MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag); is_suspended = is_ext_suspend_completed(true /* called_by_wait */, delay, bits); pending = is_external_suspend(); } // must release SR_lock to allow suspension to complete if (!pending) { // A cancelled suspend request is the only false return from // is_ext_suspend_completed() that keeps us from entering the // retry loop. *bits |= 0x00020000; return false; } if (is_suspended) { *bits |= 0x00040000; return true; } for (int i = 1; i <= retries; i++) { *bits = reset_bits; // reinit to only track last retry // We used to do an "os::yield_all(i)" call here with the intention // that yielding would increase on each retry. However, the parameter // is ignored on Linux which means the yield didn't scale up. Waiting // on the SR_lock below provides a much more predictable scale up for // the delay. It also provides a simple/direct point to check for any // safepoint requests from the VMThread { MutexLocker ml(SR_lock()); // wait with safepoint check (if we're a JavaThread - the WatcherThread // can also call this) and increase delay with each retry SR_lock()->wait(!Thread::current()->is_Java_thread(), i * delay); is_suspended = is_ext_suspend_completed(true /* called_by_wait */, delay, bits); // It is possible for the external suspend request to be cancelled // (by a resume) before the actual suspend operation is completed. // Refresh our local copy to see if we still need to wait. pending = is_external_suspend(); } if (!pending) { // A cancelled suspend request is the only false return from // is_ext_suspend_completed() that keeps us from staying in the // retry loop. *bits |= 0x00080000; return false; } if (is_suspended) { *bits |= 0x00100000; return true; } } // end retry loop // thread did not suspend after all our retries *bits |= 0x00200000; return false; } #ifndef PRODUCT void JavaThread::record_jump(address target, address instr, const char* file, int line) { // This should not need to be atomic as the only way for simultaneous // updates is via interrupts. Even then this should be rare or non-existant // and we don't care that much anyway. int index = _jmp_ring_index; _jmp_ring_index = (index + 1 ) & (jump_ring_buffer_size - 1); _jmp_ring[index]._target = (intptr_t) target; _jmp_ring[index]._instruction = (intptr_t) instr; _jmp_ring[index]._file = file; _jmp_ring[index]._line = line; } #endif /* PRODUCT */ // Called by flat profiler // Callers have already called wait_for_ext_suspend_completion // The assertion for that is currently too complex to put here: bool JavaThread::profile_last_Java_frame(frame* _fr) { bool gotframe = false; // self suspension saves needed state. if (has_last_Java_frame() && _anchor.walkable()) { *_fr = pd_last_frame(); gotframe = true; } return gotframe; } void Thread::interrupt(Thread* thread) { trace("interrupt", thread); debug_only(check_for_dangling_thread_pointer(thread);) os::interrupt(thread); } bool Thread::is_interrupted(Thread* thread, bool clear_interrupted) { trace("is_interrupted", thread); debug_only(check_for_dangling_thread_pointer(thread);) // Note: If clear_interrupted==false, this simply fetches and // returns the value of the field osthread()->interrupted(). return os::is_interrupted(thread, clear_interrupted); } // GC Support bool Thread::claim_oops_do_par_case(int strong_roots_parity) { jint thread_parity = _oops_do_parity; if (thread_parity != strong_roots_parity) { jint res = Atomic::cmpxchg(strong_roots_parity, &_oops_do_parity, thread_parity); if (res == thread_parity) { return true; } else { guarantee(res == strong_roots_parity, "Or else what?"); assert(SharedHeap::heap()->workers()->active_workers() > 0, "Should only fail when parallel."); return false; } } assert(SharedHeap::heap()->workers()->active_workers() > 0, "Should only fail when parallel."); return false; } void Thread::oops_do(OopClosure* f, CLDClosure* cld_f, CodeBlobClosure* cf) { active_handles()->oops_do(f); // Do oop for ThreadShadow f->do_oop((oop*)&_pending_exception); handle_area()->oops_do(f); } void Thread::nmethods_do(CodeBlobClosure* cf) { // no nmethods in a generic thread... } void Thread::metadata_do(void f(Metadata*)) { if (metadata_handles() != NULL) { for (int i = 0; i< metadata_handles()->length(); i++) { f(metadata_handles()->at(i)); } } } void Thread::print_on(outputStream* st) const { // get_priority assumes osthread initialized if (osthread() != NULL) { int os_prio; if (os::get_native_priority(this, &os_prio) == OS_OK) { st->print("os_prio=%d ", os_prio); } st->print("tid=" INTPTR_FORMAT " ", this); ext().print_on(st); osthread()->print_on(st); } debug_only(if (WizardMode) print_owned_locks_on(st);) } // Thread::print_on_error() is called by fatal error handler. Don't use // any lock or allocate memory. void Thread::print_on_error(outputStream* st, char* buf, int buflen) const { if (is_VM_thread()) st->print("VMThread"); else if (is_Compiler_thread()) st->print("CompilerThread"); else if (is_Java_thread()) st->print("JavaThread"); else if (is_GC_task_thread()) st->print("GCTaskThread"); else if (is_Watcher_thread()) st->print("WatcherThread"); else if (is_ConcurrentGC_thread()) st->print("ConcurrentGCThread"); else st->print("Thread"); st->print(" [stack: " PTR_FORMAT "," PTR_FORMAT "]", _stack_base - _stack_size, _stack_base); if (osthread()) { st->print(" [id=%d]", osthread()->thread_id()); } } #ifdef ASSERT void Thread::print_owned_locks_on(outputStream* st) const { Monitor *cur = _owned_locks; if (cur == NULL) { st->print(" (no locks) "); } else { st->print_cr(" Locks owned:"); while(cur) { cur->print_on(st); cur = cur->next(); } } } static int ref_use_count = 0; bool Thread::owns_locks_but_compiled_lock() const { for(Monitor *cur = _owned_locks; cur; cur = cur->next()) { if (cur != Compile_lock) return true; } return false; } #endif #ifndef PRODUCT // The flag: potential_vm_operation notifies if this particular safepoint state could potential // invoke the vm-thread (i.e., and oop allocation). In that case, we also have to make sure that // no threads which allow_vm_block's are held void Thread::check_for_valid_safepoint_state(bool potential_vm_operation) { // Check if current thread is allowed to block at a safepoint if (!(_allow_safepoint_count == 0)) fatal("Possible safepoint reached by thread that does not allow it"); if (is_Java_thread() && ((JavaThread*)this)->thread_state() != _thread_in_vm) { fatal("LEAF method calling lock?"); } #ifdef ASSERT if (potential_vm_operation && is_Java_thread() && !Universe::is_bootstrapping()) { // Make sure we do not hold any locks that the VM thread also uses. // This could potentially lead to deadlocks for(Monitor *cur = _owned_locks; cur; cur = cur->next()) { // Threads_lock is special, since the safepoint synchronization will not start before this is // acquired. Hence, a JavaThread cannot be holding it at a safepoint. So is VMOperationRequest_lock, // since it is used to transfer control between JavaThreads and the VMThread // Do not *exclude* any locks unless you are absolutly sure it is correct. Ask someone else first! if ( (cur->allow_vm_block() && cur != Threads_lock && cur != Compile_lock && // Temporary: should not be necessary when we get spearate compilation cur != VMOperationRequest_lock && cur != VMOperationQueue_lock) || cur->rank() == Mutex::special) { fatal(err_msg("Thread holding lock at safepoint that vm can block on: %s", cur->name())); } } } if (GCALotAtAllSafepoints) { // We could enter a safepoint here and thus have a gc InterfaceSupport::check_gc_alot(); } #endif } #endif bool Thread::is_in_stack(address adr) const { assert(Thread::current() == this, "is_in_stack can only be called from current thread"); address end = os::current_stack_pointer(); // Allow non Java threads to call this without stack_base if (_stack_base == NULL) return true; if (stack_base() >= adr && adr >= end) return true; return false; } bool Thread::is_in_usable_stack(address adr) const { size_t stack_guard_size = os::uses_stack_guard_pages() ? (StackYellowPages + StackRedPages) * os::vm_page_size() : 0; size_t usable_stack_size = _stack_size - stack_guard_size; return ((adr < stack_base()) && (adr >= stack_base() - usable_stack_size)); } // We had to move these methods here, because vm threads get into ObjectSynchronizer::enter // However, there is a note in JavaThread::is_lock_owned() about the VM threads not being // used for compilation in the future. If that change is made, the need for these methods // should be revisited, and they should be removed if possible. bool Thread::is_lock_owned(address adr) const { return on_local_stack(adr); } bool Thread::set_as_starting_thread() { // NOTE: this must be called inside the main thread. return os::create_main_thread((JavaThread*)this); } static void initialize_class(Symbol* class_name, TRAPS) { Klass* klass = SystemDictionary::resolve_or_fail(class_name, true, CHECK); InstanceKlass::cast(klass)->initialize(CHECK); } // Creates the initial ThreadGroup static Handle create_initial_thread_group(TRAPS) { Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_ThreadGroup(), true, CHECK_NH); instanceKlassHandle klass (THREAD, k); Handle system_instance = klass->allocate_instance_handle(CHECK_NH); { JavaValue result(T_VOID); JavaCalls::call_special(&result, system_instance, klass, vmSymbols::object_initializer_name(), vmSymbols::void_method_signature(), CHECK_NH); } Universe::set_system_thread_group(system_instance()); Handle main_instance = klass->allocate_instance_handle(CHECK_NH); { JavaValue result(T_VOID); Handle string = java_lang_String::create_from_str("main", CHECK_NH); JavaCalls::call_special(&result, main_instance, klass, vmSymbols::object_initializer_name(), vmSymbols::threadgroup_string_void_signature(), system_instance, string, CHECK_NH); } return main_instance; } // Creates the initial Thread static oop create_initial_thread(Handle thread_group, JavaThread* thread, TRAPS) { Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, CHECK_NULL); instanceKlassHandle klass (THREAD, k); instanceHandle thread_oop = klass->allocate_instance_handle(CHECK_NULL); java_lang_Thread::set_thread(thread_oop(), thread); java_lang_Thread::set_priority(thread_oop(), NormPriority); thread->set_threadObj(thread_oop()); Handle string = java_lang_String::create_from_str("main", CHECK_NULL); JavaValue result(T_VOID); JavaCalls::call_special(&result, thread_oop, klass, vmSymbols::object_initializer_name(), vmSymbols::threadgroup_string_void_signature(), thread_group, string, CHECK_NULL); return thread_oop(); } static void call_initializeSystemClass(TRAPS) { Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK); instanceKlassHandle klass (THREAD, k); JavaValue result(T_VOID); JavaCalls::call_static(&result, klass, vmSymbols::initializeSystemClass_name(), vmSymbols::void_method_signature(), CHECK); } char java_runtime_name[128] = ""; char java_runtime_version[128] = ""; // extract the JRE name from sun.misc.Version.java_runtime_name static const char* get_java_runtime_name(TRAPS) { Klass* k = SystemDictionary::find(vmSymbols::sun_misc_Version(), Handle(), Handle(), CHECK_AND_CLEAR_NULL); fieldDescriptor fd; bool found = k != NULL && InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_name_name(), vmSymbols::string_signature(), &fd); if (found) { oop name_oop = k->java_mirror()->obj_field(fd.offset()); if (name_oop == NULL) return NULL; const char* name = java_lang_String::as_utf8_string(name_oop, java_runtime_name, sizeof(java_runtime_name)); return name; } else { return NULL; } } // extract the JRE version from sun.misc.Version.java_runtime_version static const char* get_java_runtime_version(TRAPS) { Klass* k = SystemDictionary::find(vmSymbols::sun_misc_Version(), Handle(), Handle(), CHECK_AND_CLEAR_NULL); fieldDescriptor fd; bool found = k != NULL && InstanceKlass::cast(k)->find_local_field(vmSymbols::java_runtime_version_name(), vmSymbols::string_signature(), &fd); if (found) { oop name_oop = k->java_mirror()->obj_field(fd.offset()); if (name_oop == NULL) return NULL; const char* name = java_lang_String::as_utf8_string(name_oop, java_runtime_version, sizeof(java_runtime_version)); return name; } else { return NULL; } } // General purpose hook into Java code, run once when the VM is initialized. // The Java library method itself may be changed independently from the VM. static void call_postVMInitHook(TRAPS) { Klass* k = SystemDictionary::resolve_or_null(vmSymbols::sun_misc_PostVMInitHook(), THREAD); instanceKlassHandle klass (THREAD, k); if (klass.not_null()) { JavaValue result(T_VOID); JavaCalls::call_static(&result, klass, vmSymbols::run_method_name(), vmSymbols::void_method_signature(), CHECK); } } static void reset_vm_info_property(TRAPS) { // the vm info string ResourceMark rm(THREAD); const char *vm_info = VM_Version::vm_info_string(); // java.lang.System class Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_System(), true, CHECK); instanceKlassHandle klass (THREAD, k); // setProperty arguments Handle key_str = java_lang_String::create_from_str("java.vm.info", CHECK); Handle value_str = java_lang_String::create_from_str(vm_info, CHECK); // return value JavaValue r(T_OBJECT); // public static String setProperty(String key, String value); JavaCalls::call_static(&r, klass, vmSymbols::setProperty_name(), vmSymbols::string_string_string_signature(), key_str, value_str, CHECK); } void JavaThread::allocate_threadObj(Handle thread_group, char* thread_name, bool daemon, TRAPS) { assert(thread_group.not_null(), "thread group should be specified"); assert(threadObj() == NULL, "should only create Java thread object once"); Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_Thread(), true, CHECK); instanceKlassHandle klass (THREAD, k); instanceHandle thread_oop = klass->allocate_instance_handle(CHECK); java_lang_Thread::set_thread(thread_oop(), this); java_lang_Thread::set_priority(thread_oop(), NormPriority); set_threadObj(thread_oop()); JavaValue result(T_VOID); if (thread_name != NULL) { Handle name = java_lang_String::create_from_str(thread_name, CHECK); // Thread gets assigned specified name and null target JavaCalls::call_special(&result, thread_oop, klass, vmSymbols::object_initializer_name(), vmSymbols::threadgroup_string_void_signature(), thread_group, // Argument 1 name, // Argument 2 THREAD); } else { // Thread gets assigned name "Thread-nnn" and null target // (java.lang.Thread doesn't have a constructor taking only a ThreadGroup argument) JavaCalls::call_special(&result, thread_oop, klass, vmSymbols::object_initializer_name(), vmSymbols::threadgroup_runnable_void_signature(), thread_group, // Argument 1 Handle(), // Argument 2 THREAD); } if (daemon) { java_lang_Thread::set_daemon(thread_oop()); } if (HAS_PENDING_EXCEPTION) { return; } KlassHandle group(this, SystemDictionary::ThreadGroup_klass()); Handle threadObj(this, this->threadObj()); JavaCalls::call_special(&result, thread_group, group, vmSymbols::add_method_name(), vmSymbols::thread_void_signature(), threadObj, // Arg 1 THREAD); } // NamedThread -- non-JavaThread subclasses with multiple // uniquely named instances should derive from this. NamedThread::NamedThread() : Thread() { _name = NULL; _processed_thread = NULL; } NamedThread::~NamedThread() { if (_name != NULL) { FREE_C_HEAP_ARRAY(char, _name, mtThread); _name = NULL; } } void NamedThread::set_name(const char* format, ...) { guarantee(_name == NULL, "Only get to set name once."); _name = NEW_C_HEAP_ARRAY(char, max_name_len, mtThread); guarantee(_name != NULL, "alloc failure"); va_list ap; va_start(ap, format); jio_vsnprintf(_name, max_name_len, format, ap); va_end(ap); } // ======= WatcherThread ======== // The watcher thread exists to simulate timer interrupts. It should // be replaced by an abstraction over whatever native support for // timer interrupts exists on the platform. WatcherThread* WatcherThread::_watcher_thread = NULL; bool WatcherThread::_startable = false; volatile bool WatcherThread::_should_terminate = false; WatcherThread::WatcherThread() : Thread(), _crash_protection(NULL) { assert(watcher_thread() == NULL, "we can only allocate one WatcherThread"); if (os::create_thread(this, os::watcher_thread)) { _watcher_thread = this; // Set the watcher thread to the highest OS priority which should not be // used, unless a Java thread with priority java.lang.Thread.MAX_PRIORITY // is created. The only normal thread using this priority is the reference // handler thread, which runs for very short intervals only. // If the VMThread's priority is not lower than the WatcherThread profiling // will be inaccurate. os::set_priority(this, MaxPriority); if (!DisableStartThread) { os::start_thread(this); } } } int WatcherThread::sleep() const { MutexLockerEx ml(PeriodicTask_lock, Mutex::_no_safepoint_check_flag); // remaining will be zero if there are no tasks, // causing the WatcherThread to sleep until a task is // enrolled int remaining = PeriodicTask::time_to_wait(); int time_slept = 0; // we expect this to timeout - we only ever get unparked when // we should terminate or when a new task has been enrolled OSThreadWaitState osts(this->osthread(), false /* not Object.wait() */); jlong time_before_loop = os::javaTimeNanos(); for (;;) { bool timedout = PeriodicTask_lock->wait(Mutex::_no_safepoint_check_flag, remaining); jlong now = os::javaTimeNanos(); if (remaining == 0) { // if we didn't have any tasks we could have waited for a long time // consider the time_slept zero and reset time_before_loop time_slept = 0; time_before_loop = now; } else { // need to recalulate since we might have new tasks in _tasks time_slept = (int) ((now - time_before_loop) / 1000000); } // Change to task list or spurious wakeup of some kind if (timedout || _should_terminate) { break; } remaining = PeriodicTask::time_to_wait(); if (remaining == 0) { // Last task was just disenrolled so loop around and wait until // another task gets enrolled continue; } remaining -= time_slept; if (remaining <= 0) break; } return time_slept; } void WatcherThread::run() { assert(this == watcher_thread(), "just checking"); this->record_stack_base_and_size(); this->initialize_thread_local_storage(); this->set_active_handles(JNIHandleBlock::allocate_block()); while(!_should_terminate) { assert(watcher_thread() == Thread::current(), "thread consistency check"); assert(watcher_thread() == this, "thread consistency check"); // Calculate how long it'll be until the next PeriodicTask work // should be done, and sleep that amount of time. int time_waited = sleep(); if (is_error_reported()) { // A fatal error has happened, the error handler(VMError::report_and_die) // should abort JVM after creating an error log file. However in some // rare cases, the error handler itself might deadlock. Here we try to // kill JVM if the fatal error handler fails to abort in 2 minutes. // // This code is in WatcherThread because WatcherThread wakes up // periodically so the fatal error handler doesn't need to do anything; // also because the WatcherThread is less likely to crash than other // threads. for (;;) { if (!ShowMessageBoxOnError && (OnError == NULL || OnError[0] == '\0') && Arguments::abort_hook() == NULL) { os::sleep(this, 2 * 60 * 1000, false); fdStream err(defaultStream::output_fd()); err.print_raw_cr("# [ timer expired, abort... ]"); // skip atexit/vm_exit/vm_abort hooks os::die(); } // Wake up 5 seconds later, the fatal handler may reset OnError or // ShowMessageBoxOnError when it is ready to abort. os::sleep(this, 5 * 1000, false); } } PeriodicTask::real_time_tick(time_waited); } // Signal that it is terminated { MutexLockerEx mu(Terminator_lock, Mutex::_no_safepoint_check_flag); _watcher_thread = NULL; Terminator_lock->notify(); } // Thread destructor usually does this.. ThreadLocalStorage::set_thread(NULL); } void WatcherThread::start() { assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required"); if (watcher_thread() == NULL && _startable) { _should_terminate = false; // Create the single instance of WatcherThread new WatcherThread(); } } void WatcherThread::make_startable() { assert(PeriodicTask_lock->owned_by_self(), "PeriodicTask_lock required"); _startable = true; } void WatcherThread::stop() { { MutexLockerEx ml(PeriodicTask_lock, Mutex::_no_safepoint_check_flag); _should_terminate = true; OrderAccess::fence(); // ensure WatcherThread sees update in main loop WatcherThread* watcher = watcher_thread(); if (watcher != NULL) watcher->unpark(); } // it is ok to take late safepoints here, if needed MutexLocker mu(Terminator_lock); while(watcher_thread() != NULL) { // This wait should make safepoint checks, wait without a timeout, // and wait as a suspend-equivalent condition. // // Note: If the FlatProfiler is running, then this thread is waiting // for the WatcherThread to terminate and the WatcherThread, via the // FlatProfiler task, is waiting for the external suspend request on // this thread to complete. wait_for_ext_suspend_completion() will // eventually timeout, but that takes time. Making this wait a // suspend-equivalent condition solves that timeout problem. // Terminator_lock->wait(!Mutex::_no_safepoint_check_flag, 0, Mutex::_as_suspend_equivalent_flag); } } void WatcherThread::unpark() { MutexLockerEx ml(PeriodicTask_lock->owned_by_self() ? NULL : PeriodicTask_lock, Mutex::_no_safepoint_check_flag); PeriodicTask_lock->notify(); } void WatcherThread::print_on(outputStream* st) const { st->print("\"%s\" ", name()); Thread::print_on(st); st->cr(); } // ======= JavaThread ======== // A JavaThread is a normal Java thread void JavaThread::initialize() { // Initialize fields // Set the claimed par_id to UINT_MAX (ie not claiming any par_ids) set_claimed_par_id(UINT_MAX); set_saved_exception_pc(NULL); set_threadObj(NULL); _anchor.clear(); set_entry_point(NULL); set_jni_functions(jni_functions()); set_callee_target(NULL); set_vm_result(NULL); set_vm_result_2(NULL); set_vframe_array_head(NULL); set_vframe_array_last(NULL); set_deferred_locals(NULL); set_deopt_mark(NULL); set_deopt_nmethod(NULL); clear_must_deopt_id(); set_monitor_chunks(NULL); set_next(NULL); set_thread_state(_thread_new); _terminated = _not_terminated; _privileged_stack_top = NULL; _array_for_gc = NULL; _suspend_equivalent = false; _in_deopt_handler = 0; _doing_unsafe_access = false; _stack_guard_state = stack_guard_unused; (void)const_cast(_exception_oop = NULL); _exception_pc = 0; _exception_handler_pc = 0; _is_method_handle_return = 0; _jvmti_thread_state= NULL; _should_post_on_exceptions_flag = JNI_FALSE; _jvmti_get_loaded_classes_closure = NULL; _interp_only_mode = 0; _special_runtime_exit_condition = _no_async_condition; _pending_async_exception = NULL; _thread_stat = NULL; _thread_stat = new ThreadStatistics(); _blocked_on_compilation = false; _jni_active_critical = 0; _do_not_unlock_if_synchronized = false; _cached_monitor_info = NULL; _parker = Parker::Allocate(this) ; #ifndef PRODUCT _jmp_ring_index = 0; for (int ji = 0 ; ji < jump_ring_buffer_size ; ji++ ) { record_jump(NULL, NULL, NULL, 0); } #endif /* PRODUCT */ set_thread_profiler(NULL); if (FlatProfiler::is_active()) { // This is where we would decide to either give each thread it's own profiler // or use one global one from FlatProfiler, // or up to some count of the number of profiled threads, etc. ThreadProfiler* pp = new ThreadProfiler(); pp->engage(); set_thread_profiler(pp); } // Setup safepoint state info for this thread ThreadSafepointState::create(this); debug_only(_java_call_counter = 0); // JVMTI PopFrame support _popframe_condition = popframe_inactive; _popframe_preserved_args = NULL; _popframe_preserved_args_size = 0; _frames_to_pop_failed_realloc = 0; pd_initialize(); } #if INCLUDE_ALL_GCS SATBMarkQueueSet JavaThread::_satb_mark_queue_set; DirtyCardQueueSet JavaThread::_dirty_card_queue_set; #endif // INCLUDE_ALL_GCS JavaThread::JavaThread(bool is_attaching_via_jni) : Thread() #if INCLUDE_ALL_GCS , _satb_mark_queue(&_satb_mark_queue_set), _dirty_card_queue(&_dirty_card_queue_set) #endif // INCLUDE_ALL_GCS { initialize(); if (is_attaching_via_jni) { _jni_attach_state = _attaching_via_jni; } else { _jni_attach_state = _not_attaching_via_jni; } assert(deferred_card_mark().is_empty(), "Default MemRegion ctor"); } bool JavaThread::reguard_stack(address cur_sp) { if (_stack_guard_state != stack_guard_yellow_disabled) { return true; // Stack already guarded or guard pages not needed. } if (register_stack_overflow()) { // For those architectures which have separate register and // memory stacks, we must check the register stack to see if // it has overflowed. return false; } // Java code never executes within the yellow zone: the latter is only // there to provoke an exception during stack banging. If java code // is executing there, either StackShadowPages should be larger, or // some exception code in c1, c2 or the interpreter isn't unwinding // when it should. guarantee(cur_sp > stack_yellow_zone_base(), "not enough space to reguard - increase StackShadowPages"); enable_stack_yellow_zone(); return true; } bool JavaThread::reguard_stack(void) { return reguard_stack(os::current_stack_pointer()); } void JavaThread::block_if_vm_exited() { if (_terminated == _vm_exited) { // _vm_exited is set at safepoint, and Threads_lock is never released // we will block here forever Threads_lock->lock_without_safepoint_check(); ShouldNotReachHere(); } } // Remove this ifdef when C1 is ported to the compiler interface. static void compiler_thread_entry(JavaThread* thread, TRAPS); JavaThread::JavaThread(ThreadFunction entry_point, size_t stack_sz) : Thread() #if INCLUDE_ALL_GCS , _satb_mark_queue(&_satb_mark_queue_set), _dirty_card_queue(&_dirty_card_queue_set) #endif // INCLUDE_ALL_GCS { if (TraceThreadEvents) { tty->print_cr("creating thread %p", this); } initialize(); _jni_attach_state = _not_attaching_via_jni; set_entry_point(entry_point); // Create the native thread itself. // %note runtime_23 os::ThreadType thr_type = os::java_thread; thr_type = entry_point == &compiler_thread_entry ? os::compiler_thread : os::java_thread; os::create_thread(this, thr_type, stack_sz); // The _osthread may be NULL here because we ran out of memory (too many threads active). // We need to throw and OutOfMemoryError - however we cannot do this here because the caller // may hold a lock and all locks must be unlocked before throwing the exception (throwing // the exception consists of creating the exception object & initializing it, initialization // will leave the VM via a JavaCall and then all locks must be unlocked). // // The thread is still suspended when we reach here. Thread must be explicit started // by creator! Furthermore, the thread must also explicitly be added to the Threads list // by calling Threads:add. The reason why this is not done here, is because the thread // object must be fully initialized (take a look at JVM_Start) } JavaThread::~JavaThread() { if (TraceThreadEvents) { tty->print_cr("terminate thread %p", this); } // JSR166 -- return the parker to the free list Parker::Release(_parker); _parker = NULL ; // Free any remaining previous UnrollBlock vframeArray* old_array = vframe_array_last(); if (old_array != NULL) { Deoptimization::UnrollBlock* old_info = old_array->unroll_block(); old_array->set_unroll_block(NULL); delete old_info; delete old_array; } GrowableArray* deferred = deferred_locals(); if (deferred != NULL) { // This can only happen if thread is destroyed before deoptimization occurs. assert(deferred->length() != 0, "empty array!"); do { jvmtiDeferredLocalVariableSet* dlv = deferred->at(0); deferred->remove_at(0); // individual jvmtiDeferredLocalVariableSet are CHeapObj's delete dlv; } while (deferred->length() != 0); delete deferred; } // All Java related clean up happens in exit ThreadSafepointState::destroy(this); if (_thread_profiler != NULL) delete _thread_profiler; if (_thread_stat != NULL) delete _thread_stat; } // The first routine called by a new Java thread void JavaThread::run() { // initialize thread-local alloc buffer related fields this->initialize_tlab(); // used to test validitity of stack trace backs this->record_base_of_stack_pointer(); // Record real stack base and size. this->record_stack_base_and_size(); // Initialize thread local storage; set before calling MutexLocker this->initialize_thread_local_storage(); this->create_stack_guard_pages(); this->cache_global_variables(); // Thread is now sufficient initialized to be handled by the safepoint code as being // in the VM. Change thread state from _thread_new to _thread_in_vm ThreadStateTransition::transition_and_fence(this, _thread_new, _thread_in_vm); assert(JavaThread::current() == this, "sanity check"); assert(!Thread::current()->owns_locks(), "sanity check"); DTRACE_THREAD_PROBE(start, this); // This operation might block. We call that after all safepoint checks for a new thread has // been completed. this->set_active_handles(JNIHandleBlock::allocate_block()); if (JvmtiExport::should_post_thread_life()) { JvmtiExport::post_thread_start(this); } EventThreadStart event; if (event.should_commit()) { event.set_javalangthread(java_lang_Thread::thread_id(this->threadObj())); event.commit(); } // We call another function to do the rest so we are sure that the stack addresses used // from there will be lower than the stack base just computed thread_main_inner(); // Note, thread is no longer valid at this point! } void JavaThread::thread_main_inner() { assert(JavaThread::current() == this, "sanity check"); assert(this->threadObj() != NULL, "just checking"); // Execute thread entry point unless this thread has a pending exception // or has been stopped before starting. // Note: Due to JVM_StopThread we can have pending exceptions already! if (!this->has_pending_exception() && !java_lang_Thread::is_stillborn(this->threadObj())) { { ResourceMark rm(this); this->set_native_thread_name(this->get_thread_name()); } HandleMark hm(this); this->entry_point()(this, this); } DTRACE_THREAD_PROBE(stop, this); this->exit(false); delete this; } static void ensure_join(JavaThread* thread) { // We do not need to grap the Threads_lock, since we are operating on ourself. Handle threadObj(thread, thread->threadObj()); assert(threadObj.not_null(), "java thread object must exist"); ObjectLocker lock(threadObj, thread); // Ignore pending exception (ThreadDeath), since we are exiting anyway thread->clear_pending_exception(); // Thread is exiting. So set thread_status field in java.lang.Thread class to TERMINATED. java_lang_Thread::set_thread_status(threadObj(), java_lang_Thread::TERMINATED); // Clear the native thread instance - this makes isAlive return false and allows the join() // to complete once we've done the notify_all below java_lang_Thread::set_thread(threadObj(), NULL); lock.notify_all(thread); // Ignore pending exception (ThreadDeath), since we are exiting anyway thread->clear_pending_exception(); } // For any new cleanup additions, please check to see if they need to be applied to // cleanup_failed_attach_current_thread as well. void JavaThread::exit(bool destroy_vm, ExitType exit_type) { assert(this == JavaThread::current(), "thread consistency check"); HandleMark hm(this); Handle uncaught_exception(this, this->pending_exception()); this->clear_pending_exception(); Handle threadObj(this, this->threadObj()); assert(threadObj.not_null(), "Java thread object should be created"); if (get_thread_profiler() != NULL) { get_thread_profiler()->disengage(); ResourceMark rm; get_thread_profiler()->print(get_thread_name()); } // FIXIT: This code should be moved into else part, when reliable 1.2/1.3 check is in place { EXCEPTION_MARK; CLEAR_PENDING_EXCEPTION; } // FIXIT: The is_null check is only so it works better on JDK1.2 VM's. This // has to be fixed by a runtime query method if (!destroy_vm || JDK_Version::is_jdk12x_version()) { // JSR-166: change call from from ThreadGroup.uncaughtException to // java.lang.Thread.dispatchUncaughtException if (uncaught_exception.not_null()) { Handle group(this, java_lang_Thread::threadGroup(threadObj())); { EXCEPTION_MARK; // Check if the method Thread.dispatchUncaughtException() exists. If so // call it. Otherwise we have an older library without the JSR-166 changes, // so call ThreadGroup.uncaughtException() KlassHandle recvrKlass(THREAD, threadObj->klass()); CallInfo callinfo; KlassHandle thread_klass(THREAD, SystemDictionary::Thread_klass()); LinkResolver::resolve_virtual_call(callinfo, threadObj, recvrKlass, thread_klass, vmSymbols::dispatchUncaughtException_name(), vmSymbols::throwable_void_signature(), KlassHandle(), false, false, THREAD); CLEAR_PENDING_EXCEPTION; methodHandle method = callinfo.selected_method(); if (method.not_null()) { JavaValue result(T_VOID); JavaCalls::call_virtual(&result, threadObj, thread_klass, vmSymbols::dispatchUncaughtException_name(), vmSymbols::throwable_void_signature(), uncaught_exception, THREAD); } else { KlassHandle thread_group(THREAD, SystemDictionary::ThreadGroup_klass()); JavaValue result(T_VOID); JavaCalls::call_virtual(&result, group, thread_group, vmSymbols::uncaughtException_name(), vmSymbols::thread_throwable_void_signature(), threadObj, // Arg 1 uncaught_exception, // Arg 2 THREAD); } if (HAS_PENDING_EXCEPTION) { ResourceMark rm(this); jio_fprintf(defaultStream::error_stream(), "\nException: %s thrown from the UncaughtExceptionHandler" " in thread \"%s\"\n", pending_exception()->klass()->external_name(), get_thread_name()); CLEAR_PENDING_EXCEPTION; } } } // Called before the java thread exit since we want to read info // from java_lang_Thread object EventThreadEnd event; if (event.should_commit()) { event.set_javalangthread(java_lang_Thread::thread_id(this->threadObj())); event.commit(); } // Call after last event on thread EVENT_THREAD_EXIT(this); // Call Thread.exit(). We try 3 times in case we got another Thread.stop during // the execution of the method. If that is not enough, then we don't really care. Thread.stop // is deprecated anyhow. if (!is_Compiler_thread()) { int count = 3; while (java_lang_Thread::threadGroup(threadObj()) != NULL && (count-- > 0)) { EXCEPTION_MARK; JavaValue result(T_VOID); KlassHandle thread_klass(THREAD, SystemDictionary::Thread_klass()); JavaCalls::call_virtual(&result, threadObj, thread_klass, vmSymbols::exit_method_name(), vmSymbols::void_method_signature(), THREAD); CLEAR_PENDING_EXCEPTION; } } // notify JVMTI if (JvmtiExport::should_post_thread_life()) { JvmtiExport::post_thread_end(this); } // We have notified the agents that we are exiting, before we go on, // we must check for a pending external suspend request and honor it // in order to not surprise the thread that made the suspend request. while (true) { { MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag); if (!is_external_suspend()) { set_terminated(_thread_exiting); ThreadService::current_thread_exiting(this); break; } // Implied else: // Things get a little tricky here. We have a pending external // suspend request, but we are holding the SR_lock so we // can't just self-suspend. So we temporarily drop the lock // and then self-suspend. } ThreadBlockInVM tbivm(this); java_suspend_self(); // We're done with this suspend request, but we have to loop around // and check again. Eventually we will get SR_lock without a pending // external suspend request and will be able to mark ourselves as // exiting. } // no more external suspends are allowed at this point } else { // before_exit() has already posted JVMTI THREAD_END events } // Notify waiters on thread object. This has to be done after exit() is called // on the thread (if the thread is the last thread in a daemon ThreadGroup the // group should have the destroyed bit set before waiters are notified). ensure_join(this); assert(!this->has_pending_exception(), "ensure_join should have cleared"); // 6282335 JNI DetachCurrentThread spec states that all Java monitors // held by this thread must be released. A detach operation must only // get here if there are no Java frames on the stack. Therefore, any // owned monitors at this point MUST be JNI-acquired monitors which are // pre-inflated and in the monitor cache. // // ensure_join() ignores IllegalThreadStateExceptions, and so does this. if (exit_type == jni_detach && JNIDetachReleasesMonitors) { assert(!this->has_last_Java_frame(), "detaching with Java frames?"); ObjectSynchronizer::release_monitors_owned_by_thread(this); assert(!this->has_pending_exception(), "release_monitors should have cleared"); } // These things needs to be done while we are still a Java Thread. Make sure that thread // is in a consistent state, in case GC happens assert(_privileged_stack_top == NULL, "must be NULL when we get here"); if (active_handles() != NULL) { JNIHandleBlock* block = active_handles(); set_active_handles(NULL); JNIHandleBlock::release_block(block); } if (free_handle_block() != NULL) { JNIHandleBlock* block = free_handle_block(); set_free_handle_block(NULL); JNIHandleBlock::release_block(block); } // These have to be removed while this is still a valid thread. remove_stack_guard_pages(); if (UseTLAB) { tlab().make_parsable(true); // retire TLAB } if (JvmtiEnv::environments_might_exist()) { JvmtiExport::cleanup_thread(this); } // We must flush any deferred card marks before removing a thread from // the list of active threads. Universe::heap()->flush_deferred_store_barrier(this); assert(deferred_card_mark().is_empty(), "Should have been flushed"); #if INCLUDE_ALL_GCS // We must flush the G1-related buffers before removing a thread // from the list of active threads. We must do this after any deferred // card marks have been flushed (above) so that any entries that are // added to the thread's dirty card queue as a result are not lost. if (UseG1GC) { flush_barrier_queues(); } #endif // INCLUDE_ALL_GCS // Remove from list of active threads list, and notify VM thread if we are the last non-daemon thread Threads::remove(this); } #if INCLUDE_ALL_GCS // Flush G1-related queues. void JavaThread::flush_barrier_queues() { satb_mark_queue().flush(); dirty_card_queue().flush(); } void JavaThread::initialize_queues() { assert(!SafepointSynchronize::is_at_safepoint(), "we should not be at a safepoint"); ObjPtrQueue& satb_queue = satb_mark_queue(); SATBMarkQueueSet& satb_queue_set = satb_mark_queue_set(); // The SATB queue should have been constructed with its active // field set to false. assert(!satb_queue.is_active(), "SATB queue should not be active"); assert(satb_queue.is_empty(), "SATB queue should be empty"); // If we are creating the thread during a marking cycle, we should // set the active field of the SATB queue to true. if (satb_queue_set.is_active()) { satb_queue.set_active(true); } DirtyCardQueue& dirty_queue = dirty_card_queue(); // The dirty card queue should have been constructed with its // active field set to true. assert(dirty_queue.is_active(), "dirty card queue should be active"); } #endif // INCLUDE_ALL_GCS void JavaThread::cleanup_failed_attach_current_thread() { if (get_thread_profiler() != NULL) { get_thread_profiler()->disengage(); ResourceMark rm; get_thread_profiler()->print(get_thread_name()); } if (active_handles() != NULL) { JNIHandleBlock* block = active_handles(); set_active_handles(NULL); JNIHandleBlock::release_block(block); } if (free_handle_block() != NULL) { JNIHandleBlock* block = free_handle_block(); set_free_handle_block(NULL); JNIHandleBlock::release_block(block); } // These have to be removed while this is still a valid thread. remove_stack_guard_pages(); if (UseTLAB) { tlab().make_parsable(true); // retire TLAB, if any } #if INCLUDE_ALL_GCS if (UseG1GC) { flush_barrier_queues(); } #endif // INCLUDE_ALL_GCS Threads::remove(this); delete this; } JavaThread* JavaThread::active() { Thread* thread = ThreadLocalStorage::thread(); assert(thread != NULL, "just checking"); if (thread->is_Java_thread()) { return (JavaThread*) thread; } else { assert(thread->is_VM_thread(), "this must be a vm thread"); VM_Operation* op = ((VMThread*) thread)->vm_operation(); JavaThread *ret=op == NULL ? NULL : (JavaThread *)op->calling_thread(); assert(ret->is_Java_thread(), "must be a Java thread"); return ret; } } bool JavaThread::is_lock_owned(address adr) const { if (Thread::is_lock_owned(adr)) return true; for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) { if (chunk->contains(adr)) return true; } return false; } void JavaThread::add_monitor_chunk(MonitorChunk* chunk) { chunk->set_next(monitor_chunks()); set_monitor_chunks(chunk); } void JavaThread::remove_monitor_chunk(MonitorChunk* chunk) { guarantee(monitor_chunks() != NULL, "must be non empty"); if (monitor_chunks() == chunk) { set_monitor_chunks(chunk->next()); } else { MonitorChunk* prev = monitor_chunks(); while (prev->next() != chunk) prev = prev->next(); prev->set_next(chunk->next()); } } // JVM support. // Note: this function shouldn't block if it's called in // _thread_in_native_trans state (such as from // check_special_condition_for_native_trans()). void JavaThread::check_and_handle_async_exceptions(bool check_unsafe_error) { if (has_last_Java_frame() && has_async_condition()) { // If we are at a polling page safepoint (not a poll return) // then we must defer async exception because live registers // will be clobbered by the exception path. Poll return is // ok because the call we a returning from already collides // with exception handling registers and so there is no issue. // (The exception handling path kills call result registers but // this is ok since the exception kills the result anyway). if (is_at_poll_safepoint()) { // if the code we are returning to has deoptimized we must defer // the exception otherwise live registers get clobbered on the // exception path before deoptimization is able to retrieve them. // RegisterMap map(this, false); frame caller_fr = last_frame().sender(&map); assert(caller_fr.is_compiled_frame(), "what?"); if (caller_fr.is_deoptimized_frame()) { if (TraceExceptions) { ResourceMark rm; tty->print_cr("deferred async exception at compiled safepoint"); } return; } } } JavaThread::AsyncRequests condition = clear_special_runtime_exit_condition(); if (condition == _no_async_condition) { // Conditions have changed since has_special_runtime_exit_condition() // was called: // - if we were here only because of an external suspend request, // then that was taken care of above (or cancelled) so we are done // - if we were here because of another async request, then it has // been cleared between the has_special_runtime_exit_condition() // and now so again we are done return; } // Check for pending async. exception if (_pending_async_exception != NULL) { // Only overwrite an already pending exception, if it is not a threadDeath. if (!has_pending_exception() || !pending_exception()->is_a(SystemDictionary::ThreadDeath_klass())) { // We cannot call Exceptions::_throw(...) here because we cannot block set_pending_exception(_pending_async_exception, __FILE__, __LINE__); if (TraceExceptions) { ResourceMark rm; tty->print("Async. exception installed at runtime exit (" INTPTR_FORMAT ")", this); if (has_last_Java_frame() ) { frame f = last_frame(); tty->print(" (pc: " INTPTR_FORMAT " sp: " INTPTR_FORMAT " )", f.pc(), f.sp()); } tty->print_cr(" of type: %s", InstanceKlass::cast(_pending_async_exception->klass())->external_name()); } _pending_async_exception = NULL; clear_has_async_exception(); } } if (check_unsafe_error && condition == _async_unsafe_access_error && !has_pending_exception()) { condition = _no_async_condition; // done switch (thread_state()) { case _thread_in_vm: { JavaThread* THREAD = this; THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation"); } case _thread_in_native: { ThreadInVMfromNative tiv(this); JavaThread* THREAD = this; THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in an unsafe memory access operation"); } case _thread_in_Java: { ThreadInVMfromJava tiv(this); JavaThread* THREAD = this; THROW_MSG(vmSymbols::java_lang_InternalError(), "a fault occurred in a recent unsafe memory access operation in compiled Java code"); } default: ShouldNotReachHere(); } } assert(condition == _no_async_condition || has_pending_exception() || (!check_unsafe_error && condition == _async_unsafe_access_error), "must have handled the async condition, if no exception"); } void JavaThread::handle_special_runtime_exit_condition(bool check_asyncs) { // // Check for pending external suspend. Internal suspend requests do // not use handle_special_runtime_exit_condition(). // If JNIEnv proxies are allowed, don't self-suspend if the target // thread is not the current thread. In older versions of jdbx, jdbx // threads could call into the VM with another thread's JNIEnv so we // can be here operating on behalf of a suspended thread (4432884). bool do_self_suspend = is_external_suspend_with_lock(); if (do_self_suspend && (!AllowJNIEnvProxy || this == JavaThread::current())) { // // Because thread is external suspended the safepoint code will count // thread as at a safepoint. This can be odd because we can be here // as _thread_in_Java which would normally transition to _thread_blocked // at a safepoint. We would like to mark the thread as _thread_blocked // before calling java_suspend_self like all other callers of it but // we must then observe proper safepoint protocol. (We can't leave // _thread_blocked with a safepoint in progress). However we can be // here as _thread_in_native_trans so we can't use a normal transition // constructor/destructor pair because they assert on that type of // transition. We could do something like: // // JavaThreadState state = thread_state(); // set_thread_state(_thread_in_vm); // { // ThreadBlockInVM tbivm(this); // java_suspend_self() // } // set_thread_state(_thread_in_vm_trans); // if (safepoint) block; // set_thread_state(state); // // but that is pretty messy. Instead we just go with the way the // code has worked before and note that this is the only path to // java_suspend_self that doesn't put the thread in _thread_blocked // mode. frame_anchor()->make_walkable(this); java_suspend_self(); // We might be here for reasons in addition to the self-suspend request // so check for other async requests. } if (check_asyncs) { check_and_handle_async_exceptions(); } } void JavaThread::send_thread_stop(oop java_throwable) { assert(Thread::current()->is_VM_thread(), "should be in the vm thread"); assert(Threads_lock->is_locked(), "Threads_lock should be locked by safepoint code"); assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped"); // Do not throw asynchronous exceptions against the compiler thread // (the compiler thread should not be a Java thread -- fix in 1.4.2) if (is_Compiler_thread()) return; { // Actually throw the Throwable against the target Thread - however // only if there is no thread death exception installed already. if (_pending_async_exception == NULL || !_pending_async_exception->is_a(SystemDictionary::ThreadDeath_klass())) { // If the topmost frame is a runtime stub, then we are calling into // OptoRuntime from compiled code. Some runtime stubs (new, monitor_exit..) // must deoptimize the caller before continuing, as the compiled exception handler table // may not be valid if (has_last_Java_frame()) { frame f = last_frame(); if (f.is_runtime_frame() || f.is_safepoint_blob_frame()) { // BiasedLocking needs an updated RegisterMap for the revoke monitors pass RegisterMap reg_map(this, UseBiasedLocking); frame compiled_frame = f.sender(®_map); if (!StressCompiledExceptionHandlers && compiled_frame.can_be_deoptimized()) { Deoptimization::deoptimize(this, compiled_frame, ®_map); } } } // Set async. pending exception in thread. set_pending_async_exception(java_throwable); if (TraceExceptions) { ResourceMark rm; tty->print_cr("Pending Async. exception installed of type: %s", InstanceKlass::cast(_pending_async_exception->klass())->external_name()); } // for AbortVMOnException flag NOT_PRODUCT(Exceptions::debug_check_abort(InstanceKlass::cast(_pending_async_exception->klass())->external_name())); } } // Interrupt thread so it will wake up from a potential wait() Thread::interrupt(this); } // External suspension mechanism. // // Tell the VM to suspend a thread when ever it knows that it does not hold on // to any VM_locks and it is at a transition // Self-suspension will happen on the transition out of the vm. // Catch "this" coming in from JNIEnv pointers when the thread has been freed // // Guarantees on return: // + Target thread will not execute any new bytecode (that's why we need to // force a safepoint) // + Target thread will not enter any new monitors // void JavaThread::java_suspend() { { MutexLocker mu(Threads_lock); if (!Threads::includes(this) || is_exiting() || this->threadObj() == NULL) { return; } } { MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag); if (!is_external_suspend()) { // a racing resume has cancelled us; bail out now return; } // suspend is done uint32_t debug_bits = 0; // Warning: is_ext_suspend_completed() may temporarily drop the // SR_lock to allow the thread to reach a stable thread state if // it is currently in a transient thread state. if (is_ext_suspend_completed(false /* !called_by_wait */, SuspendRetryDelay, &debug_bits) ) { return; } } VM_ForceSafepoint vm_suspend; VMThread::execute(&vm_suspend); } // Part II of external suspension. // A JavaThread self suspends when it detects a pending external suspend // request. This is usually on transitions. It is also done in places // where continuing to the next transition would surprise the caller, // e.g., monitor entry. // // Returns the number of times that the thread self-suspended. // // Note: DO NOT call java_suspend_self() when you just want to block current // thread. java_suspend_self() is the second stage of cooperative // suspension for external suspend requests and should only be used // to complete an external suspend request. // int JavaThread::java_suspend_self() { int ret = 0; // we are in the process of exiting so don't suspend if (is_exiting()) { clear_external_suspend(); return ret; } assert(_anchor.walkable() || (is_Java_thread() && !((JavaThread*)this)->has_last_Java_frame()), "must have walkable stack"); MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag); assert(!this->is_ext_suspended(), "a thread trying to self-suspend should not already be suspended"); if (this->is_suspend_equivalent()) { // If we are self-suspending as a result of the lifting of a // suspend equivalent condition, then the suspend_equivalent // flag is not cleared until we set the ext_suspended flag so // that wait_for_ext_suspend_completion() returns consistent // results. this->clear_suspend_equivalent(); } // A racing resume may have cancelled us before we grabbed SR_lock // above. Or another external suspend request could be waiting for us // by the time we return from SR_lock()->wait(). The thread // that requested the suspension may already be trying to walk our // stack and if we return now, we can change the stack out from under // it. This would be a "bad thing (TM)" and cause the stack walker // to crash. We stay self-suspended until there are no more pending // external suspend requests. while (is_external_suspend()) { ret++; this->set_ext_suspended(); // _ext_suspended flag is cleared by java_resume() while (is_ext_suspended()) { this->SR_lock()->wait(Mutex::_no_safepoint_check_flag); } } return ret; } #ifdef ASSERT // verify the JavaThread has not yet been published in the Threads::list, and // hence doesn't need protection from concurrent access at this stage void JavaThread::verify_not_published() { if (!Threads_lock->owned_by_self()) { MutexLockerEx ml(Threads_lock, Mutex::_no_safepoint_check_flag); assert( !Threads::includes(this), "java thread shouldn't have been published yet!"); } else { assert( !Threads::includes(this), "java thread shouldn't have been published yet!"); } } #endif // Slow path when the native==>VM/Java barriers detect a safepoint is in // progress or when _suspend_flags is non-zero. // Current thread needs to self-suspend if there is a suspend request and/or // block if a safepoint is in progress. // Async exception ISN'T checked. // Note only the ThreadInVMfromNative transition can call this function // directly and when thread state is _thread_in_native_trans void JavaThread::check_safepoint_and_suspend_for_native_trans(JavaThread *thread) { assert(thread->thread_state() == _thread_in_native_trans, "wrong state"); JavaThread *curJT = JavaThread::current(); bool do_self_suspend = thread->is_external_suspend(); assert(!curJT->has_last_Java_frame() || curJT->frame_anchor()->walkable(), "Unwalkable stack in native->vm transition"); // If JNIEnv proxies are allowed, don't self-suspend if the target // thread is not the current thread. In older versions of jdbx, jdbx // threads could call into the VM with another thread's JNIEnv so we // can be here operating on behalf of a suspended thread (4432884). if (do_self_suspend && (!AllowJNIEnvProxy || curJT == thread)) { JavaThreadState state = thread->thread_state(); // We mark this thread_blocked state as a suspend-equivalent so // that a caller to is_ext_suspend_completed() won't be confused. // The suspend-equivalent state is cleared by java_suspend_self(). thread->set_suspend_equivalent(); // If the safepoint code sees the _thread_in_native_trans state, it will // wait until the thread changes to other thread state. There is no // guarantee on how soon we can obtain the SR_lock and complete the // self-suspend request. It would be a bad idea to let safepoint wait for // too long. Temporarily change the state to _thread_blocked to // let the VM thread know that this thread is ready for GC. The problem // of changing thread state is that safepoint could happen just after // java_suspend_self() returns after being resumed, and VM thread will // see the _thread_blocked state. We must check for safepoint // after restoring the state and make sure we won't leave while a safepoint // is in progress. thread->set_thread_state(_thread_blocked); thread->java_suspend_self(); thread->set_thread_state(state); // Make sure new state is seen by VM thread if (os::is_MP()) { if (UseMembar) { // Force a fence between the write above and read below OrderAccess::fence(); } else { // Must use this rather than serialization page in particular on Windows InterfaceSupport::serialize_memory(thread); } } } if (SafepointSynchronize::do_call_back()) { // If we are safepointing, then block the caller which may not be // the same as the target thread (see above). SafepointSynchronize::block(curJT); } if (thread->is_deopt_suspend()) { thread->clear_deopt_suspend(); RegisterMap map(thread, false); frame f = thread->last_frame(); while ( f.id() != thread->must_deopt_id() && ! f.is_first_frame()) { f = f.sender(&map); } if (f.id() == thread->must_deopt_id()) { thread->clear_must_deopt_id(); f.deoptimize(thread); } else { fatal("missed deoptimization!"); } } } // Slow path when the native==>VM/Java barriers detect a safepoint is in // progress or when _suspend_flags is non-zero. // Current thread needs to self-suspend if there is a suspend request and/or // block if a safepoint is in progress. // Also check for pending async exception (not including unsafe access error). // Note only the native==>VM/Java barriers can call this function and when // thread state is _thread_in_native_trans. void JavaThread::check_special_condition_for_native_trans(JavaThread *thread) { check_safepoint_and_suspend_for_native_trans(thread); if (thread->has_async_exception()) { // We are in _thread_in_native_trans state, don't handle unsafe // access error since that may block. thread->check_and_handle_async_exceptions(false); } } // This is a variant of the normal // check_special_condition_for_native_trans with slightly different // semantics for use by critical native wrappers. It does all the // normal checks but also performs the transition back into // thread_in_Java state. This is required so that critical natives // can potentially block and perform a GC if they are the last thread // exiting the GC_locker. void JavaThread::check_special_condition_for_native_trans_and_transition(JavaThread *thread) { check_special_condition_for_native_trans(thread); // Finish the transition thread->set_thread_state(_thread_in_Java); if (thread->do_critical_native_unlock()) { ThreadInVMfromJavaNoAsyncException tiv(thread); GC_locker::unlock_critical(thread); thread->clear_critical_native_unlock(); } } // We need to guarantee the Threads_lock here, since resumes are not // allowed during safepoint synchronization // Can only resume from an external suspension void JavaThread::java_resume() { assert_locked_or_safepoint(Threads_lock); // Sanity check: thread is gone, has started exiting or the thread // was not externally suspended. if (!Threads::includes(this) || is_exiting() || !is_external_suspend()) { return; } MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag); clear_external_suspend(); if (is_ext_suspended()) { clear_ext_suspended(); SR_lock()->notify_all(); } } void JavaThread::create_stack_guard_pages() { if (! os::uses_stack_guard_pages() || _stack_guard_state != stack_guard_unused) return; address low_addr = stack_base() - stack_size(); size_t len = (StackYellowPages + StackRedPages) * os::vm_page_size(); int allocate = os::allocate_stack_guard_pages(); // warning("Guarding at " PTR_FORMAT " for len " SIZE_FORMAT "\n", low_addr, len); if (allocate && !os::create_stack_guard_pages((char *) low_addr, len)) { warning("Attempt to allocate stack guard pages failed."); return; } if (os::guard_memory((char *) low_addr, len)) { _stack_guard_state = stack_guard_enabled; } else { warning("Attempt to protect stack guard pages failed."); if (os::uncommit_memory((char *) low_addr, len)) { warning("Attempt to deallocate stack guard pages failed."); } } } void JavaThread::remove_stack_guard_pages() { assert(Thread::current() == this, "from different thread"); if (_stack_guard_state == stack_guard_unused) return; address low_addr = stack_base() - stack_size(); size_t len = (StackYellowPages + StackRedPages) * os::vm_page_size(); if (os::allocate_stack_guard_pages()) { if (os::remove_stack_guard_pages((char *) low_addr, len)) { _stack_guard_state = stack_guard_unused; } else { warning("Attempt to deallocate stack guard pages failed."); } } else { if (_stack_guard_state == stack_guard_unused) return; if (os::unguard_memory((char *) low_addr, len)) { _stack_guard_state = stack_guard_unused; } else { warning("Attempt to unprotect stack guard pages failed."); } } } void JavaThread::enable_stack_yellow_zone() { assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); assert(_stack_guard_state != stack_guard_enabled, "already enabled"); // The base notation is from the stacks point of view, growing downward. // We need to adjust it to work correctly with guard_memory() address base = stack_yellow_zone_base() - stack_yellow_zone_size(); guarantee(base < stack_base(),"Error calculating stack yellow zone"); guarantee(base < os::current_stack_pointer(),"Error calculating stack yellow zone"); if (os::guard_memory((char *) base, stack_yellow_zone_size())) { _stack_guard_state = stack_guard_enabled; } else { warning("Attempt to guard stack yellow zone failed."); } enable_register_stack_guard(); } void JavaThread::disable_stack_yellow_zone() { assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); assert(_stack_guard_state != stack_guard_yellow_disabled, "already disabled"); // Simply return if called for a thread that does not use guard pages. if (_stack_guard_state == stack_guard_unused) return; // The base notation is from the stacks point of view, growing downward. // We need to adjust it to work correctly with guard_memory() address base = stack_yellow_zone_base() - stack_yellow_zone_size(); if (os::unguard_memory((char *)base, stack_yellow_zone_size())) { _stack_guard_state = stack_guard_yellow_disabled; } else { warning("Attempt to unguard stack yellow zone failed."); } disable_register_stack_guard(); } void JavaThread::enable_stack_red_zone() { // The base notation is from the stacks point of view, growing downward. // We need to adjust it to work correctly with guard_memory() assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); address base = stack_red_zone_base() - stack_red_zone_size(); guarantee(base < stack_base(),"Error calculating stack red zone"); guarantee(base < os::current_stack_pointer(),"Error calculating stack red zone"); if(!os::guard_memory((char *) base, stack_red_zone_size())) { warning("Attempt to guard stack red zone failed."); } } void JavaThread::disable_stack_red_zone() { // The base notation is from the stacks point of view, growing downward. // We need to adjust it to work correctly with guard_memory() assert(_stack_guard_state != stack_guard_unused, "must be using guard pages."); address base = stack_red_zone_base() - stack_red_zone_size(); if (!os::unguard_memory((char *)base, stack_red_zone_size())) { warning("Attempt to unguard stack red zone failed."); } } void JavaThread::frames_do(void f(frame*, const RegisterMap* map)) { // ignore is there is no stack if (!has_last_Java_frame()) return; // traverse the stack frames. Starts from top frame. for(StackFrameStream fst(this); !fst.is_done(); fst.next()) { frame* fr = fst.current(); f(fr, fst.register_map()); } } #ifndef PRODUCT // Deoptimization // Function for testing deoptimization void JavaThread::deoptimize() { // BiasedLocking needs an updated RegisterMap for the revoke monitors pass StackFrameStream fst(this, UseBiasedLocking); bool deopt = false; // Dump stack only if a deopt actually happens. bool only_at = strlen(DeoptimizeOnlyAt) > 0; // Iterate over all frames in the thread and deoptimize for(; !fst.is_done(); fst.next()) { if(fst.current()->can_be_deoptimized()) { if (only_at) { // Deoptimize only at particular bcis. DeoptimizeOnlyAt // consists of comma or carriage return separated numbers so // search for the current bci in that string. address pc = fst.current()->pc(); nmethod* nm = (nmethod*) fst.current()->cb(); ScopeDesc* sd = nm->scope_desc_at( pc); char buffer[8]; jio_snprintf(buffer, sizeof(buffer), "%d", sd->bci()); size_t len = strlen(buffer); const char * found = strstr(DeoptimizeOnlyAt, buffer); while (found != NULL) { if ((found[len] == ',' || found[len] == '\n' || found[len] == '\0') && (found == DeoptimizeOnlyAt || found[-1] == ',' || found[-1] == '\n')) { // Check that the bci found is bracketed by terminators. break; } found = strstr(found + 1, buffer); } if (!found) { continue; } } if (DebugDeoptimization && !deopt) { deopt = true; // One-time only print before deopt tty->print_cr("[BEFORE Deoptimization]"); trace_frames(); trace_stack(); } Deoptimization::deoptimize(this, *fst.current(), fst.register_map()); } } if (DebugDeoptimization && deopt) { tty->print_cr("[AFTER Deoptimization]"); trace_frames(); } } // Make zombies void JavaThread::make_zombies() { for(StackFrameStream fst(this); !fst.is_done(); fst.next()) { if (fst.current()->can_be_deoptimized()) { // it is a Java nmethod nmethod* nm = CodeCache::find_nmethod(fst.current()->pc()); nm->make_not_entrant(); } } } #endif // PRODUCT void JavaThread::deoptimized_wrt_marked_nmethods() { if (!has_last_Java_frame()) return; // BiasedLocking needs an updated RegisterMap for the revoke monitors pass StackFrameStream fst(this, UseBiasedLocking); for(; !fst.is_done(); fst.next()) { if (fst.current()->should_be_deoptimized()) { if (LogCompilation && xtty != NULL) { nmethod* nm = fst.current()->cb()->as_nmethod_or_null(); xtty->elem("deoptimized thread='" UINTX_FORMAT "' compile_id='%d'", this->name(), nm != NULL ? nm->compile_id() : -1); } Deoptimization::deoptimize(this, *fst.current(), fst.register_map()); } } } // GC support static void frame_gc_epilogue(frame* f, const RegisterMap* map) { f->gc_epilogue(); } void JavaThread::gc_epilogue() { frames_do(frame_gc_epilogue); } static void frame_gc_prologue(frame* f, const RegisterMap* map) { f->gc_prologue(); } void JavaThread::gc_prologue() { frames_do(frame_gc_prologue); } // If the caller is a NamedThread, then remember, in the current scope, // the given JavaThread in its _processed_thread field. class RememberProcessedThread: public StackObj { NamedThread* _cur_thr; public: RememberProcessedThread(JavaThread* jthr) { Thread* thread = Thread::current(); if (thread->is_Named_thread()) { _cur_thr = (NamedThread *)thread; _cur_thr->set_processed_thread(jthr); } else { _cur_thr = NULL; } } ~RememberProcessedThread() { if (_cur_thr) { _cur_thr->set_processed_thread(NULL); } } }; void JavaThread::oops_do(OopClosure* f, CLDClosure* cld_f, CodeBlobClosure* cf) { // Verify that the deferred card marks have been flushed. assert(deferred_card_mark().is_empty(), "Should be empty during GC"); // The ThreadProfiler oops_do is done from FlatProfiler::oops_do // since there may be more than one thread using each ThreadProfiler. // Traverse the GCHandles Thread::oops_do(f, cld_f, cf); assert( (!has_last_Java_frame() && java_call_counter() == 0) || (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!"); if (has_last_Java_frame()) { // Record JavaThread to GC thread RememberProcessedThread rpt(this); // Traverse the privileged stack if (_privileged_stack_top != NULL) { _privileged_stack_top->oops_do(f); } // traverse the registered growable array if (_array_for_gc != NULL) { for (int index = 0; index < _array_for_gc->length(); index++) { f->do_oop(_array_for_gc->adr_at(index)); } } // Traverse the monitor chunks for (MonitorChunk* chunk = monitor_chunks(); chunk != NULL; chunk = chunk->next()) { chunk->oops_do(f); } // Traverse the execution stack for(StackFrameStream fst(this); !fst.is_done(); fst.next()) { fst.current()->oops_do(f, cld_f, cf, fst.register_map()); } } // callee_target is never live across a gc point so NULL it here should // it still contain a methdOop. set_callee_target(NULL); assert(vframe_array_head() == NULL, "deopt in progress at a safepoint!"); // If we have deferred set_locals there might be oops waiting to be // written GrowableArray* list = deferred_locals(); if (list != NULL) { for (int i = 0; i < list->length(); i++) { list->at(i)->oops_do(f); } } // Traverse instance variables at the end since the GC may be moving things // around using this function f->do_oop((oop*) &_threadObj); f->do_oop((oop*) &_vm_result); f->do_oop((oop*) &_exception_oop); f->do_oop((oop*) &_pending_async_exception); if (jvmti_thread_state() != NULL) { jvmti_thread_state()->oops_do(f); } } void JavaThread::nmethods_do(CodeBlobClosure* cf) { Thread::nmethods_do(cf); // (super method is a no-op) assert( (!has_last_Java_frame() && java_call_counter() == 0) || (has_last_Java_frame() && java_call_counter() > 0), "wrong java_sp info!"); if (has_last_Java_frame()) { // Traverse the execution stack for(StackFrameStream fst(this); !fst.is_done(); fst.next()) { fst.current()->nmethods_do(cf); } } } void JavaThread::metadata_do(void f(Metadata*)) { Thread::metadata_do(f); if (has_last_Java_frame()) { // Traverse the execution stack to call f() on the methods in the stack for(StackFrameStream fst(this); !fst.is_done(); fst.next()) { fst.current()->metadata_do(f); } } else if (is_Compiler_thread()) { // need to walk ciMetadata in current compile tasks to keep alive. CompilerThread* ct = (CompilerThread*)this; if (ct->env() != NULL) { ct->env()->metadata_do(f); } } } // Printing const char* _get_thread_state_name(JavaThreadState _thread_state) { switch (_thread_state) { case _thread_uninitialized: return "_thread_uninitialized"; case _thread_new: return "_thread_new"; case _thread_new_trans: return "_thread_new_trans"; case _thread_in_native: return "_thread_in_native"; case _thread_in_native_trans: return "_thread_in_native_trans"; case _thread_in_vm: return "_thread_in_vm"; case _thread_in_vm_trans: return "_thread_in_vm_trans"; case _thread_in_Java: return "_thread_in_Java"; case _thread_in_Java_trans: return "_thread_in_Java_trans"; case _thread_blocked: return "_thread_blocked"; case _thread_blocked_trans: return "_thread_blocked_trans"; default: return "unknown thread state"; } } #ifndef PRODUCT void JavaThread::print_thread_state_on(outputStream *st) const { st->print_cr(" JavaThread state: %s", _get_thread_state_name(_thread_state)); }; void JavaThread::print_thread_state() const { print_thread_state_on(tty); }; #endif // PRODUCT // Called by Threads::print() for VM_PrintThreads operation void JavaThread::print_on(outputStream *st) const { st->print("\"%s\" ", get_thread_name()); oop thread_oop = threadObj(); if (thread_oop != NULL) { st->print("#" INT64_FORMAT " ", java_lang_Thread::thread_id(thread_oop)); if (java_lang_Thread::is_daemon(thread_oop)) st->print("daemon "); st->print("prio=%d ", java_lang_Thread::priority(thread_oop)); } Thread::print_on(st); // print guess for valid stack memory region (assume 4K pages); helps lock debugging st->print_cr("[" INTPTR_FORMAT "]", (intptr_t)last_Java_sp() & ~right_n_bits(12)); if (thread_oop != NULL && JDK_Version::is_gte_jdk15x_version()) { st->print_cr(" java.lang.Thread.State: %s", java_lang_Thread::thread_status_name(thread_oop)); } #ifndef PRODUCT print_thread_state_on(st); _safepoint_state->print_on(st); #endif // PRODUCT } // Called by fatal error handler. The difference between this and // JavaThread::print() is that we can't grab lock or allocate memory. void JavaThread::print_on_error(outputStream* st, char *buf, int buflen) const { st->print("JavaThread \"%s\"", get_thread_name_string(buf, buflen)); oop thread_obj = threadObj(); if (thread_obj != NULL) { if (java_lang_Thread::is_daemon(thread_obj)) st->print(" daemon"); } st->print(" ["); st->print("%s", _get_thread_state_name(_thread_state)); if (osthread()) { st->print(", id=%d", osthread()->thread_id()); } st->print(", stack(" PTR_FORMAT "," PTR_FORMAT ")", _stack_base - _stack_size, _stack_base); st->print("]"); return; } // Verification static void frame_verify(frame* f, const RegisterMap *map) { f->verify(map); } void JavaThread::verify() { // Verify oops in the thread. oops_do(&VerifyOopClosure::verify_oop, NULL, NULL); // Verify the stack frames. frames_do(frame_verify); } // CR 6300358 (sub-CR 2137150) // Most callers of this method assume that it can't return NULL but a // thread may not have a name whilst it is in the process of attaching to // the VM - see CR 6412693, and there are places where a JavaThread can be // seen prior to having it's threadObj set (eg JNI attaching threads and // if vm exit occurs during initialization). These cases can all be accounted // for such that this method never returns NULL. const char* JavaThread::get_thread_name() const { #ifdef ASSERT // early safepoints can hit while current thread does not yet have TLS if (!SafepointSynchronize::is_at_safepoint()) { Thread *cur = Thread::current(); if (!(cur->is_Java_thread() && cur == this)) { // Current JavaThreads are allowed to get their own name without // the Threads_lock. assert_locked_or_safepoint(Threads_lock); } } #endif // ASSERT return get_thread_name_string(); } // Returns a non-NULL representation of this thread's name, or a suitable // descriptive string if there is no set name const char* JavaThread::get_thread_name_string(char* buf, int buflen) const { const char* name_str; oop thread_obj = threadObj(); if (thread_obj != NULL) { typeArrayOop name = java_lang_Thread::name(thread_obj); if (name != NULL) { if (buf == NULL) { name_str = UNICODE::as_utf8((jchar*) name->base(T_CHAR), name->length()); } else { name_str = UNICODE::as_utf8((jchar*) name->base(T_CHAR), name->length(), buf, buflen); } } else if (is_attaching_via_jni()) { // workaround for 6412693 - see 6404306 name_str = ""; } else { name_str = Thread::name(); } } else { name_str = Thread::name(); } assert(name_str != NULL, "unexpected NULL thread name"); return name_str; } const char* JavaThread::get_threadgroup_name() const { debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);) oop thread_obj = threadObj(); if (thread_obj != NULL) { oop thread_group = java_lang_Thread::threadGroup(thread_obj); if (thread_group != NULL) { typeArrayOop name = java_lang_ThreadGroup::name(thread_group); // ThreadGroup.name can be null if (name != NULL) { const char* str = UNICODE::as_utf8((jchar*) name->base(T_CHAR), name->length()); return str; } } } return NULL; } const char* JavaThread::get_parent_name() const { debug_only(if (JavaThread::current() != this) assert_locked_or_safepoint(Threads_lock);) oop thread_obj = threadObj(); if (thread_obj != NULL) { oop thread_group = java_lang_Thread::threadGroup(thread_obj); if (thread_group != NULL) { oop parent = java_lang_ThreadGroup::parent(thread_group); if (parent != NULL) { typeArrayOop name = java_lang_ThreadGroup::name(parent); // ThreadGroup.name can be null if (name != NULL) { const char* str = UNICODE::as_utf8((jchar*) name->base(T_CHAR), name->length()); return str; } } } } return NULL; } ThreadPriority JavaThread::java_priority() const { oop thr_oop = threadObj(); if (thr_oop == NULL) return NormPriority; // Bootstrapping ThreadPriority priority = java_lang_Thread::priority(thr_oop); assert(MinPriority <= priority && priority <= MaxPriority, "sanity check"); return priority; } void JavaThread::prepare(jobject jni_thread, ThreadPriority prio) { assert(Threads_lock->owner() == Thread::current(), "must have threads lock"); // Link Java Thread object <-> C++ Thread // Get the C++ thread object (an oop) from the JNI handle (a jthread) // and put it into a new Handle. The Handle "thread_oop" can then // be used to pass the C++ thread object to other methods. // Set the Java level thread object (jthread) field of the // new thread (a JavaThread *) to C++ thread object using the // "thread_oop" handle. // Set the thread field (a JavaThread *) of the // oop representing the java_lang_Thread to the new thread (a JavaThread *). Handle thread_oop(Thread::current(), JNIHandles::resolve_non_null(jni_thread)); assert(InstanceKlass::cast(thread_oop->klass())->is_linked(), "must be initialized"); set_threadObj(thread_oop()); java_lang_Thread::set_thread(thread_oop(), this); if (prio == NoPriority) { prio = java_lang_Thread::priority(thread_oop()); assert(prio != NoPriority, "A valid priority should be present"); } // Push the Java priority down to the native thread; needs Threads_lock Thread::set_priority(this, prio); prepare_ext(); // Add the new thread to the Threads list and set it in motion. // We must have threads lock in order to call Threads::add. // It is crucial that we do not block before the thread is // added to the Threads list for if a GC happens, then the java_thread oop // will not be visited by GC. Threads::add(this); } oop JavaThread::current_park_blocker() { // Support for JSR-166 locks oop thread_oop = threadObj(); if (thread_oop != NULL && JDK_Version::current().supports_thread_park_blocker()) { return java_lang_Thread::park_blocker(thread_oop); } return NULL; } void JavaThread::print_stack_on(outputStream* st) { if (!has_last_Java_frame()) return; ResourceMark rm; HandleMark hm; RegisterMap reg_map(this); vframe* start_vf = last_java_vframe(®_map); int count = 0; for (vframe* f = start_vf; f; f = f->sender() ) { if (f->is_java_frame()) { javaVFrame* jvf = javaVFrame::cast(f); java_lang_Throwable::print_stack_element(st, jvf->method(), jvf->bci()); // Print out lock information if (JavaMonitorsInStackTrace) { jvf->print_lock_info_on(st, count); } } else { // Ignore non-Java frames } // Bail-out case for too deep stacks count++; if (MaxJavaStackTraceDepth == count) return; } } // JVMTI PopFrame support void JavaThread::popframe_preserve_args(ByteSize size_in_bytes, void* start) { assert(_popframe_preserved_args == NULL, "should not wipe out old PopFrame preserved arguments"); if (in_bytes(size_in_bytes) != 0) { _popframe_preserved_args = NEW_C_HEAP_ARRAY(char, in_bytes(size_in_bytes), mtThread); _popframe_preserved_args_size = in_bytes(size_in_bytes); Copy::conjoint_jbytes(start, _popframe_preserved_args, _popframe_preserved_args_size); } } void* JavaThread::popframe_preserved_args() { return _popframe_preserved_args; } ByteSize JavaThread::popframe_preserved_args_size() { return in_ByteSize(_popframe_preserved_args_size); } WordSize JavaThread::popframe_preserved_args_size_in_words() { int sz = in_bytes(popframe_preserved_args_size()); assert(sz % wordSize == 0, "argument size must be multiple of wordSize"); return in_WordSize(sz / wordSize); } void JavaThread::popframe_free_preserved_args() { assert(_popframe_preserved_args != NULL, "should not free PopFrame preserved arguments twice"); FREE_C_HEAP_ARRAY(char, (char*) _popframe_preserved_args, mtThread); _popframe_preserved_args = NULL; _popframe_preserved_args_size = 0; } #ifndef PRODUCT void JavaThread::trace_frames() { tty->print_cr("[Describe stack]"); int frame_no = 1; for(StackFrameStream fst(this); !fst.is_done(); fst.next()) { tty->print(" %d. ", frame_no++); fst.current()->print_value_on(tty,this); tty->cr(); } } class PrintAndVerifyOopClosure: public OopClosure { protected: template inline void do_oop_work(T* p) { oop obj = oopDesc::load_decode_heap_oop(p); if (obj == NULL) return; tty->print(INTPTR_FORMAT ": ", p); if (obj->is_oop_or_null()) { if (obj->is_objArray()) { tty->print_cr("valid objArray: " INTPTR_FORMAT, (oopDesc*) obj); } else { obj->print(); } } else { tty->print_cr("invalid oop: " INTPTR_FORMAT, (oopDesc*) obj); } tty->cr(); } public: virtual void do_oop(oop* p) { do_oop_work(p); } virtual void do_oop(narrowOop* p) { do_oop_work(p); } }; static void oops_print(frame* f, const RegisterMap *map) { PrintAndVerifyOopClosure print; f->print_value(); f->oops_do(&print, NULL, NULL, (RegisterMap*)map); } // Print our all the locations that contain oops and whether they are // valid or not. This useful when trying to find the oldest frame // where an oop has gone bad since the frame walk is from youngest to // oldest. void JavaThread::trace_oops() { tty->print_cr("[Trace oops]"); frames_do(oops_print); } #ifdef ASSERT // Print or validate the layout of stack frames void JavaThread::print_frame_layout(int depth, bool validate_only) { ResourceMark rm; PRESERVE_EXCEPTION_MARK; FrameValues values; int frame_no = 0; for(StackFrameStream fst(this, false); !fst.is_done(); fst.next()) { fst.current()->describe(values, ++frame_no); if (depth == frame_no) break; } if (validate_only) { values.validate(); } else { tty->print_cr("[Describe stack layout]"); values.print(this); } } #endif void JavaThread::trace_stack_from(vframe* start_vf) { ResourceMark rm; int vframe_no = 1; for (vframe* f = start_vf; f; f = f->sender() ) { if (f->is_java_frame()) { javaVFrame::cast(f)->print_activation(vframe_no++); } else { f->print(); } if (vframe_no > StackPrintLimit) { tty->print_cr("......"); return; } } } void JavaThread::trace_stack() { if (!has_last_Java_frame()) return; ResourceMark rm; HandleMark hm; RegisterMap reg_map(this); trace_stack_from(last_java_vframe(®_map)); } #endif // PRODUCT javaVFrame* JavaThread::last_java_vframe(RegisterMap *reg_map) { assert(reg_map != NULL, "a map must be given"); frame f = last_frame(); for (vframe* vf = vframe::new_vframe(&f, reg_map, this); vf; vf = vf->sender() ) { if (vf->is_java_frame()) return javaVFrame::cast(vf); } return NULL; } Klass* JavaThread::security_get_caller_class(int depth) { vframeStream vfst(this); vfst.security_get_caller_frame(depth); if (!vfst.at_end()) { return vfst.method()->method_holder(); } return NULL; } static void compiler_thread_entry(JavaThread* thread, TRAPS) { assert(thread->is_Compiler_thread(), "must be compiler thread"); CompileBroker::compiler_thread_loop(); } // Create a CompilerThread CompilerThread::CompilerThread(CompileQueue* queue, CompilerCounters* counters) : JavaThread(&compiler_thread_entry) { _env = NULL; _log = NULL; _task = NULL; _queue = queue; _counters = counters; _buffer_blob = NULL; _scanned_nmethod = NULL; _compiler = NULL; #ifndef PRODUCT _ideal_graph_printer = NULL; #endif } void CompilerThread::oops_do(OopClosure* f, CLDClosure* cld_f, CodeBlobClosure* cf) { JavaThread::oops_do(f, cld_f, cf); if (_scanned_nmethod != NULL && cf != NULL) { // Safepoints can occur when the sweeper is scanning an nmethod so // process it here to make sure it isn't unloaded in the middle of // a scan. cf->do_code_blob(_scanned_nmethod); } } // ======= Threads ======== // The Threads class links together all active threads, and provides // operations over all threads. It is protected by its own Mutex // lock, which is also used in other contexts to protect thread // operations from having the thread being operated on from exiting // and going away unexpectedly (e.g., safepoint synchronization) JavaThread* Threads::_thread_list = NULL; int Threads::_number_of_threads = 0; int Threads::_number_of_non_daemon_threads = 0; int Threads::_return_code = 0; size_t JavaThread::_stack_size_at_create = 0; #ifdef ASSERT bool Threads::_vm_complete = false; #endif // All JavaThreads #define ALL_JAVA_THREADS(X) for (JavaThread* X = _thread_list; X; X = X->next()) // All JavaThreads + all non-JavaThreads (i.e., every thread in the system) void Threads::threads_do(ThreadClosure* tc) { assert_locked_or_safepoint(Threads_lock); // ALL_JAVA_THREADS iterates through all JavaThreads ALL_JAVA_THREADS(p) { tc->do_thread(p); } // Someday we could have a table or list of all non-JavaThreads. // For now, just manually iterate through them. tc->do_thread(VMThread::vm_thread()); Universe::heap()->gc_threads_do(tc); WatcherThread *wt = WatcherThread::watcher_thread(); // Strictly speaking, the following NULL check isn't sufficient to make sure // the data for WatcherThread is still valid upon being examined. However, // considering that WatchThread terminates when the VM is on the way to // exit at safepoint, the chance of the above is extremely small. The right // way to prevent termination of WatcherThread would be to acquire // Terminator_lock, but we can't do that without violating the lock rank // checking in some cases. if (wt != NULL) tc->do_thread(wt); // If CompilerThreads ever become non-JavaThreads, add them here } jint Threads::create_vm(JavaVMInitArgs* args, bool* canTryAgain) { extern void JDK_Version_init(); // Check version if (!is_supported_jni_version(args->version)) return JNI_EVERSION; // Initialize the output stream module ostream_init(); // Process java launcher properties. Arguments::process_sun_java_launcher_properties(args); // Initialize the os module before using TLS os::init(); // Initialize system properties. Arguments::init_system_properties(); // So that JDK version can be used as a discrimintor when parsing arguments JDK_Version_init(); // Update/Initialize System properties after JDK version number is known Arguments::init_version_specific_system_properties(); // Parse arguments jint parse_result = Arguments::parse(args); if (parse_result != JNI_OK) return parse_result; os::init_before_ergo(); jint ergo_result = Arguments::apply_ergo(); if (ergo_result != JNI_OK) return ergo_result; if (PauseAtStartup) { os::pause(); } #ifndef USDT2 HS_DTRACE_PROBE(hotspot, vm__init__begin); #else /* USDT2 */ HOTSPOT_VM_INIT_BEGIN(); #endif /* USDT2 */ // Record VM creation timing statistics TraceVmCreationTime create_vm_timer; create_vm_timer.start(); // Timing (must come after argument parsing) TraceTime timer("Create VM", TraceStartupTime); // Initialize the os module after parsing the args jint os_init_2_result = os::init_2(); if (os_init_2_result != JNI_OK) return os_init_2_result; jint adjust_after_os_result = Arguments::adjust_after_os(); if (adjust_after_os_result != JNI_OK) return adjust_after_os_result; // intialize TLS ThreadLocalStorage::init(); // Initialize output stream logging ostream_init_log(); // Convert -Xrun to -agentlib: if there is no JVM_OnLoad // Must be before create_vm_init_agents() if (Arguments::init_libraries_at_startup()) { convert_vm_init_libraries_to_agents(); } // Launch -agentlib/-agentpath and converted -Xrun agents if (Arguments::init_agents_at_startup()) { create_vm_init_agents(); } // Initialize Threads state _thread_list = NULL; _number_of_threads = 0; _number_of_non_daemon_threads = 0; // Initialize global data structures and create system classes in heap vm_init_globals(); // Attach the main thread to this os thread JavaThread* main_thread = new JavaThread(); main_thread->set_thread_state(_thread_in_vm); // must do this before set_active_handles and initialize_thread_local_storage // Note: on solaris initialize_thread_local_storage() will (indirectly) // change the stack size recorded here to one based on the java thread // stacksize. This adjusted size is what is used to figure the placement // of the guard pages. main_thread->record_stack_base_and_size(); main_thread->initialize_thread_local_storage(); main_thread->set_active_handles(JNIHandleBlock::allocate_block()); if (!main_thread->set_as_starting_thread()) { vm_shutdown_during_initialization( "Failed necessary internal allocation. Out of swap space"); delete main_thread; *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again return JNI_ENOMEM; } // Enable guard page *after* os::create_main_thread(), otherwise it would // crash Linux VM, see notes in os_linux.cpp. main_thread->create_stack_guard_pages(); // Initialize Java-Level synchronization subsystem ObjectMonitor::Initialize() ; // Initialize global modules jint status = init_globals(); if (status != JNI_OK) { delete main_thread; *canTryAgain = false; // don't let caller call JNI_CreateJavaVM again return status; } // Should be done after the heap is fully created main_thread->cache_global_variables(); HandleMark hm; { MutexLocker mu(Threads_lock); Threads::add(main_thread); } // Any JVMTI raw monitors entered in onload will transition into // real raw monitor. VM is setup enough here for raw monitor enter. JvmtiExport::transition_pending_onload_raw_monitors(); // Create the VMThread { TraceTime timer("Start VMThread", TraceStartupTime); VMThread::create(); Thread* vmthread = VMThread::vm_thread(); if (!os::create_thread(vmthread, os::vm_thread)) vm_exit_during_initialization("Cannot create VM thread. Out of system resources."); // Wait for the VM thread to become ready, and VMThread::run to initialize // Monitors can have spurious returns, must always check another state flag { MutexLocker ml(Notify_lock); os::start_thread(vmthread); while (vmthread->active_handles() == NULL) { Notify_lock->wait(); } } } assert (Universe::is_fully_initialized(), "not initialized"); if (VerifyDuringStartup) { // Make sure we're starting with a clean slate. VM_Verify verify_op; VMThread::execute(&verify_op); } EXCEPTION_MARK; // At this point, the Universe is initialized, but we have not executed // any byte code. Now is a good time (the only time) to dump out the // internal state of the JVM for sharing. if (DumpSharedSpaces) { MetaspaceShared::preload_and_dump(CHECK_0); ShouldNotReachHere(); } // Always call even when there are not JVMTI environments yet, since environments // may be attached late and JVMTI must track phases of VM execution JvmtiExport::enter_start_phase(); // Notify JVMTI agents that VM has started (JNI is up) - nop if no agents. JvmtiExport::post_vm_start(); { TraceTime timer("Initialize java.lang classes", TraceStartupTime); if (EagerXrunInit && Arguments::init_libraries_at_startup()) { create_vm_init_libraries(); } initialize_class(vmSymbols::java_lang_String(), CHECK_0); // Initialize java_lang.System (needed before creating the thread) initialize_class(vmSymbols::java_lang_System(), CHECK_0); initialize_class(vmSymbols::java_lang_ThreadGroup(), CHECK_0); Handle thread_group = create_initial_thread_group(CHECK_0); Universe::set_main_thread_group(thread_group()); initialize_class(vmSymbols::java_lang_Thread(), CHECK_0); oop thread_object = create_initial_thread(thread_group, main_thread, CHECK_0); main_thread->set_threadObj(thread_object); // Set thread status to running since main thread has // been started and running. java_lang_Thread::set_thread_status(thread_object, java_lang_Thread::RUNNABLE); // The VM creates & returns objects of this class. Make sure it's initialized. initialize_class(vmSymbols::java_lang_Class(), CHECK_0); // The VM preresolves methods to these classes. Make sure that they get initialized initialize_class(vmSymbols::java_lang_reflect_Method(), CHECK_0); initialize_class(vmSymbols::java_lang_ref_Finalizer(), CHECK_0); call_initializeSystemClass(CHECK_0); // get the Java runtime name after java.lang.System is initialized JDK_Version::set_runtime_name(get_java_runtime_name(THREAD)); JDK_Version::set_runtime_version(get_java_runtime_version(THREAD)); // an instance of OutOfMemory exception has been allocated earlier initialize_class(vmSymbols::java_lang_OutOfMemoryError(), CHECK_0); initialize_class(vmSymbols::java_lang_NullPointerException(), CHECK_0); initialize_class(vmSymbols::java_lang_ClassCastException(), CHECK_0); initialize_class(vmSymbols::java_lang_ArrayStoreException(), CHECK_0); initialize_class(vmSymbols::java_lang_ArithmeticException(), CHECK_0); initialize_class(vmSymbols::java_lang_StackOverflowError(), CHECK_0); initialize_class(vmSymbols::java_lang_IllegalMonitorStateException(), CHECK_0); initialize_class(vmSymbols::java_lang_IllegalArgumentException(), CHECK_0); } // See : bugid 4211085. // Background : the static initializer of java.lang.Compiler tries to read // property"java.compiler" and read & write property "java.vm.info". // When a security manager is installed through the command line // option "-Djava.security.manager", the above properties are not // readable and the static initializer for java.lang.Compiler fails // resulting in a NoClassDefFoundError. This can happen in any // user code which calls methods in java.lang.Compiler. // Hack : the hack is to pre-load and initialize this class, so that only // system domains are on the stack when the properties are read. // Currently even the AWT code has calls to methods in java.lang.Compiler. // On the classic VM, java.lang.Compiler is loaded very early to load the JIT. // Future Fix : the best fix is to grant everyone permissions to read "java.compiler" and // read and write"java.vm.info" in the default policy file. See bugid 4211383 // Once that is done, we should remove this hack. initialize_class(vmSymbols::java_lang_Compiler(), CHECK_0); // More hackery - the static initializer of java.lang.Compiler adds the string "nojit" to // the java.vm.info property if no jit gets loaded through java.lang.Compiler (the hotspot // compiler does not get loaded through java.lang.Compiler). "java -version" with the // hotspot vm says "nojit" all the time which is confusing. So, we reset it here. // This should also be taken out as soon as 4211383 gets fixed. reset_vm_info_property(CHECK_0); quicken_jni_functions(); // Must be run after init_ft which initializes ft_enabled if (TRACE_INITIALIZE() != JNI_OK) { vm_exit_during_initialization("Failed to initialize tracing backend"); } // Set flag that basic initialization has completed. Used by exceptions and various // debug stuff, that does not work until all basic classes have been initialized. set_init_completed(); Metaspace::post_initialize(); #ifndef USDT2 HS_DTRACE_PROBE(hotspot, vm__init__end); #else /* USDT2 */ HOTSPOT_VM_INIT_END(); #endif /* USDT2 */ // record VM initialization completion time #if INCLUDE_MANAGEMENT Management::record_vm_init_completed(); #endif // INCLUDE_MANAGEMENT // Compute system loader. Note that this has to occur after set_init_completed, since // valid exceptions may be thrown in the process. // Note that we do not use CHECK_0 here since we are inside an EXCEPTION_MARK and // set_init_completed has just been called, causing exceptions not to be shortcut // anymore. We call vm_exit_during_initialization directly instead. SystemDictionary::compute_java_system_loader(THREAD); if (HAS_PENDING_EXCEPTION) { vm_exit_during_initialization(Handle(THREAD, PENDING_EXCEPTION)); } #if INCLUDE_ALL_GCS // Support for ConcurrentMarkSweep. This should be cleaned up // and better encapsulated. The ugly nested if test would go away // once things are properly refactored. XXX YSR if (UseConcMarkSweepGC || UseG1GC) { if (UseConcMarkSweepGC) { ConcurrentMarkSweepThread::makeSurrogateLockerThread(THREAD); } else { ConcurrentMarkThread::makeSurrogateLockerThread(THREAD); } if (HAS_PENDING_EXCEPTION) { vm_exit_during_initialization(Handle(THREAD, PENDING_EXCEPTION)); } } #endif // INCLUDE_ALL_GCS // Always call even when there are not JVMTI environments yet, since environments // may be attached late and JVMTI must track phases of VM execution JvmtiExport::enter_live_phase(); // Signal Dispatcher needs to be started before VMInit event is posted os::signal_init(); // Start Attach Listener if +StartAttachListener or it can't be started lazily if (!DisableAttachMechanism) { AttachListener::vm_start(); if (StartAttachListener || AttachListener::init_at_startup()) { AttachListener::init(); } } // Launch -Xrun agents // Must be done in the JVMTI live phase so that for backward compatibility the JDWP // back-end can launch with -Xdebug -Xrunjdwp. if (!EagerXrunInit && Arguments::init_libraries_at_startup()) { create_vm_init_libraries(); } // Notify JVMTI agents that VM initialization is complete - nop if no agents. JvmtiExport::post_vm_initialized(); if (TRACE_START() != JNI_OK) { vm_exit_during_initialization("Failed to start tracing backend."); } if (CleanChunkPoolAsync) { Chunk::start_chunk_pool_cleaner_task(); } // initialize compiler(s) #if defined(COMPILER1) || defined(COMPILER2) || defined(SHARK) CompileBroker::compilation_init(); #endif if (EnableInvokeDynamic) { // Pre-initialize some JSR292 core classes to avoid deadlock during class loading. // It is done after compilers are initialized, because otherwise compilations of // signature polymorphic MH intrinsics can be missed // (see SystemDictionary::find_method_handle_intrinsic). initialize_class(vmSymbols::java_lang_invoke_MethodHandle(), CHECK_0); initialize_class(vmSymbols::java_lang_invoke_MemberName(), CHECK_0); initialize_class(vmSymbols::java_lang_invoke_MethodHandleNatives(), CHECK_0); } #if INCLUDE_MANAGEMENT Management::initialize(THREAD); #endif // INCLUDE_MANAGEMENT if (HAS_PENDING_EXCEPTION) { // management agent fails to start possibly due to // configuration problem and is responsible for printing // stack trace if appropriate. Simply exit VM. vm_exit(1); } if (Arguments::has_profile()) FlatProfiler::engage(main_thread, true); if (MemProfiling) MemProfiler::engage(); StatSampler::engage(); if (CheckJNICalls) JniPeriodicChecker::engage(); BiasedLocking::init(); #if INCLUDE_RTM_OPT RTMLockingCounters::init(); #endif if (JDK_Version::current().post_vm_init_hook_enabled()) { call_postVMInitHook(THREAD); // The Java side of PostVMInitHook.run must deal with all // exceptions and provide means of diagnosis. if (HAS_PENDING_EXCEPTION) { CLEAR_PENDING_EXCEPTION; } } { MutexLockerEx ml(PeriodicTask_lock, Mutex::_no_safepoint_check_flag); // Make sure the watcher thread can be started by WatcherThread::start() // or by dynamic enrollment. WatcherThread::make_startable(); // Start up the WatcherThread if there are any periodic tasks // NOTE: All PeriodicTasks should be registered by now. If they // aren't, late joiners might appear to start slowly (we might // take a while to process their first tick). if (PeriodicTask::num_tasks() > 0) { WatcherThread::start(); } } // Give os specific code one last chance to start os::init_3(); create_vm_timer.end(); #ifdef ASSERT _vm_complete = true; #endif return JNI_OK; } // type for the Agent_OnLoad and JVM_OnLoad entry points extern "C" { typedef jint (JNICALL *OnLoadEntry_t)(JavaVM *, char *, void *); } // Find a command line agent library and return its entry point for // -agentlib: -agentpath: -Xrun // num_symbol_entries must be passed-in since only the caller knows the number of symbols in the array. static OnLoadEntry_t lookup_on_load(AgentLibrary* agent, const char *on_load_symbols[], size_t num_symbol_entries) { OnLoadEntry_t on_load_entry = NULL; void *library = NULL; if (!agent->valid()) { char buffer[JVM_MAXPATHLEN]; char ebuf[1024]; const char *name = agent->name(); const char *msg = "Could not find agent library "; // First check to see if agent is statically linked into executable if (os::find_builtin_agent(agent, on_load_symbols, num_symbol_entries)) { library = agent->os_lib(); } else if (agent->is_absolute_path()) { library = os::dll_load(name, ebuf, sizeof ebuf); if (library == NULL) { const char *sub_msg = " in absolute path, with error: "; size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1; char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread); jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf); // If we can't find the agent, exit. vm_exit_during_initialization(buf, NULL); FREE_C_HEAP_ARRAY(char, buf, mtThread); } } else { // Try to load the agent from the standard dll directory if (os::dll_build_name(buffer, sizeof(buffer), Arguments::get_dll_dir(), name)) { library = os::dll_load(buffer, ebuf, sizeof ebuf); } if (library == NULL) { // Try the local directory char ns[1] = {0}; if (os::dll_build_name(buffer, sizeof(buffer), ns, name)) { library = os::dll_load(buffer, ebuf, sizeof ebuf); } if (library == NULL) { const char *sub_msg = " on the library path, with error: "; size_t len = strlen(msg) + strlen(name) + strlen(sub_msg) + strlen(ebuf) + 1; char *buf = NEW_C_HEAP_ARRAY(char, len, mtThread); jio_snprintf(buf, len, "%s%s%s%s", msg, name, sub_msg, ebuf); // If we can't find the agent, exit. vm_exit_during_initialization(buf, NULL); FREE_C_HEAP_ARRAY(char, buf, mtThread); } } } agent->set_os_lib(library); agent->set_valid(); } // Find the OnLoad function. on_load_entry = CAST_TO_FN_PTR(OnLoadEntry_t, os::find_agent_function(agent, false, on_load_symbols, num_symbol_entries)); return on_load_entry; } // Find the JVM_OnLoad entry point static OnLoadEntry_t lookup_jvm_on_load(AgentLibrary* agent) { const char *on_load_symbols[] = JVM_ONLOAD_SYMBOLS; return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*)); } // Find the Agent_OnLoad entry point static OnLoadEntry_t lookup_agent_on_load(AgentLibrary* agent) { const char *on_load_symbols[] = AGENT_ONLOAD_SYMBOLS; return lookup_on_load(agent, on_load_symbols, sizeof(on_load_symbols) / sizeof(char*)); } // For backwards compatibility with -Xrun // Convert libraries with no JVM_OnLoad, but which have Agent_OnLoad to be // treated like -agentpath: // Must be called before agent libraries are created void Threads::convert_vm_init_libraries_to_agents() { AgentLibrary* agent; AgentLibrary* next; for (agent = Arguments::libraries(); agent != NULL; agent = next) { next = agent->next(); // cache the next agent now as this agent may get moved off this list OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent); // If there is an JVM_OnLoad function it will get called later, // otherwise see if there is an Agent_OnLoad if (on_load_entry == NULL) { on_load_entry = lookup_agent_on_load(agent); if (on_load_entry != NULL) { // switch it to the agent list -- so that Agent_OnLoad will be called, // JVM_OnLoad won't be attempted and Agent_OnUnload will Arguments::convert_library_to_agent(agent); } else { vm_exit_during_initialization("Could not find JVM_OnLoad or Agent_OnLoad function in the library", agent->name()); } } } } // Create agents for -agentlib: -agentpath: and converted -Xrun // Invokes Agent_OnLoad // Called very early -- before JavaThreads exist void Threads::create_vm_init_agents() { extern struct JavaVM_ main_vm; AgentLibrary* agent; JvmtiExport::enter_onload_phase(); for (agent = Arguments::agents(); agent != NULL; agent = agent->next()) { OnLoadEntry_t on_load_entry = lookup_agent_on_load(agent); if (on_load_entry != NULL) { // Invoke the Agent_OnLoad function jint err = (*on_load_entry)(&main_vm, agent->options(), NULL); if (err != JNI_OK) { vm_exit_during_initialization("agent library failed to init", agent->name()); } } else { vm_exit_during_initialization("Could not find Agent_OnLoad function in the agent library", agent->name()); } } JvmtiExport::enter_primordial_phase(); } extern "C" { typedef void (JNICALL *Agent_OnUnload_t)(JavaVM *); } void Threads::shutdown_vm_agents() { // Send any Agent_OnUnload notifications const char *on_unload_symbols[] = AGENT_ONUNLOAD_SYMBOLS; size_t num_symbol_entries = ARRAY_SIZE(on_unload_symbols); extern struct JavaVM_ main_vm; for (AgentLibrary* agent = Arguments::agents(); agent != NULL; agent = agent->next()) { // Find the Agent_OnUnload function. Agent_OnUnload_t unload_entry = CAST_TO_FN_PTR(Agent_OnUnload_t, os::find_agent_function(agent, false, on_unload_symbols, num_symbol_entries)); // Invoke the Agent_OnUnload function if (unload_entry != NULL) { JavaThread* thread = JavaThread::current(); ThreadToNativeFromVM ttn(thread); HandleMark hm(thread); (*unload_entry)(&main_vm); } } } // Called for after the VM is initialized for -Xrun libraries which have not been converted to agent libraries // Invokes JVM_OnLoad void Threads::create_vm_init_libraries() { extern struct JavaVM_ main_vm; AgentLibrary* agent; for (agent = Arguments::libraries(); agent != NULL; agent = agent->next()) { OnLoadEntry_t on_load_entry = lookup_jvm_on_load(agent); if (on_load_entry != NULL) { // Invoke the JVM_OnLoad function JavaThread* thread = JavaThread::current(); ThreadToNativeFromVM ttn(thread); HandleMark hm(thread); jint err = (*on_load_entry)(&main_vm, agent->options(), NULL); if (err != JNI_OK) { vm_exit_during_initialization("-Xrun library failed to init", agent->name()); } } else { vm_exit_during_initialization("Could not find JVM_OnLoad function in -Xrun library", agent->name()); } } } JavaThread* Threads::find_java_thread_from_java_tid(jlong java_tid) { assert(Threads_lock->owned_by_self(), "Must hold Threads_lock"); JavaThread* java_thread = NULL; // Sequential search for now. Need to do better optimization later. for (JavaThread* thread = Threads::first(); thread != NULL; thread = thread->next()) { oop tobj = thread->threadObj(); if (!thread->is_exiting() && tobj != NULL && java_tid == java_lang_Thread::thread_id(tobj)) { java_thread = thread; break; } } return java_thread; } // Last thread running calls java.lang.Shutdown.shutdown() void JavaThread::invoke_shutdown_hooks() { HandleMark hm(this); // We could get here with a pending exception, if so clear it now. if (this->has_pending_exception()) { this->clear_pending_exception(); } EXCEPTION_MARK; Klass* k = SystemDictionary::resolve_or_null(vmSymbols::java_lang_Shutdown(), THREAD); if (k != NULL) { // SystemDictionary::resolve_or_null will return null if there was // an exception. If we cannot load the Shutdown class, just don't // call Shutdown.shutdown() at all. This will mean the shutdown hooks // and finalizers (if runFinalizersOnExit is set) won't be run. // Note that if a shutdown hook was registered or runFinalizersOnExit // was called, the Shutdown class would have already been loaded // (Runtime.addShutdownHook and runFinalizersOnExit will load it). instanceKlassHandle shutdown_klass (THREAD, k); JavaValue result(T_VOID); JavaCalls::call_static(&result, shutdown_klass, vmSymbols::shutdown_method_name(), vmSymbols::void_method_signature(), THREAD); } CLEAR_PENDING_EXCEPTION; } // Threads::destroy_vm() is normally called from jni_DestroyJavaVM() when // the program falls off the end of main(). Another VM exit path is through // vm_exit() when the program calls System.exit() to return a value or when // there is a serious error in VM. The two shutdown paths are not exactly // the same, but they share Shutdown.shutdown() at Java level and before_exit() // and VM_Exit op at VM level. // // Shutdown sequence: // + Shutdown native memory tracking if it is on // + Wait until we are the last non-daemon thread to execute // <-- every thing is still working at this moment --> // + Call java.lang.Shutdown.shutdown(), which will invoke Java level // shutdown hooks, run finalizers if finalization-on-exit // + Call before_exit(), prepare for VM exit // > run VM level shutdown hooks (they are registered through JVM_OnExit(), // currently the only user of this mechanism is File.deleteOnExit()) // > stop flat profiler, StatSampler, watcher thread, CMS threads, // post thread end and vm death events to JVMTI, // stop signal thread // + Call JavaThread::exit(), it will: // > release JNI handle blocks, remove stack guard pages // > remove this thread from Threads list // <-- no more Java code from this thread after this point --> // + Stop VM thread, it will bring the remaining VM to a safepoint and stop // the compiler threads at safepoint // <-- do not use anything that could get blocked by Safepoint --> // + Disable tracing at JNI/JVM barriers // + Set _vm_exited flag for threads that are still running native code // + Delete this thread // + Call exit_globals() // > deletes tty // > deletes PerfMemory resources // + Return to caller bool Threads::destroy_vm() { JavaThread* thread = JavaThread::current(); #ifdef ASSERT _vm_complete = false; #endif // Wait until we are the last non-daemon thread to execute { MutexLocker nu(Threads_lock); while (Threads::number_of_non_daemon_threads() > 1 ) // This wait should make safepoint checks, wait without a timeout, // and wait as a suspend-equivalent condition. // // Note: If the FlatProfiler is running and this thread is waiting // for another non-daemon thread to finish, then the FlatProfiler // is waiting for the external suspend request on this thread to // complete. wait_for_ext_suspend_completion() will eventually // timeout, but that takes time. Making this wait a suspend- // equivalent condition solves that timeout problem. // Threads_lock->wait(!Mutex::_no_safepoint_check_flag, 0, Mutex::_as_suspend_equivalent_flag); } // Hang forever on exit if we are reporting an error. if (ShowMessageBoxOnError && is_error_reported()) { os::infinite_sleep(); } os::wait_for_keypress_at_exit(); if (JDK_Version::is_jdk12x_version()) { // We are the last thread running, so check if finalizers should be run. // For 1.3 or later this is done in thread->invoke_shutdown_hooks() HandleMark rm(thread); Universe::run_finalizers_on_exit(); } else { // run Java level shutdown hooks thread->invoke_shutdown_hooks(); } before_exit(thread); thread->exit(true); // Stop VM thread. { // 4945125 The vm thread comes to a safepoint during exit. // GC vm_operations can get caught at the safepoint, and the // heap is unparseable if they are caught. Grab the Heap_lock // to prevent this. The GC vm_operations will not be able to // queue until after the vm thread is dead. After this point, // we'll never emerge out of the safepoint before the VM exits. MutexLocker ml(Heap_lock); VMThread::wait_for_vm_thread_exit(); assert(SafepointSynchronize::is_at_safepoint(), "VM thread should exit at Safepoint"); VMThread::destroy(); } // clean up ideal graph printers #if defined(COMPILER2) && !defined(PRODUCT) IdealGraphPrinter::clean_up(); #endif // Now, all Java threads are gone except daemon threads. Daemon threads // running Java code or in VM are stopped by the Safepoint. However, // daemon threads executing native code are still running. But they // will be stopped at native=>Java/VM barriers. Note that we can't // simply kill or suspend them, as it is inherently deadlock-prone. #ifndef PRODUCT // disable function tracing at JNI/JVM barriers TraceJNICalls = false; TraceJVMCalls = false; TraceRuntimeCalls = false; #endif VM_Exit::set_vm_exited(); notify_vm_shutdown(); delete thread; // exit_globals() will delete tty exit_globals(); return true; } jboolean Threads::is_supported_jni_version_including_1_1(jint version) { if (version == JNI_VERSION_1_1) return JNI_TRUE; return is_supported_jni_version(version); } jboolean Threads::is_supported_jni_version(jint version) { if (version == JNI_VERSION_1_2) return JNI_TRUE; if (version == JNI_VERSION_1_4) return JNI_TRUE; if (version == JNI_VERSION_1_6) return JNI_TRUE; if (version == JNI_VERSION_1_8) return JNI_TRUE; return JNI_FALSE; } void Threads::add(JavaThread* p, bool force_daemon) { // The threads lock must be owned at this point assert_locked_or_safepoint(Threads_lock); // See the comment for this method in thread.hpp for its purpose and // why it is called here. p->initialize_queues(); p->set_next(_thread_list); _thread_list = p; _number_of_threads++; oop threadObj = p->threadObj(); bool daemon = true; // Bootstrapping problem: threadObj can be null for initial // JavaThread (or for threads attached via JNI) if ((!force_daemon) && (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj))) { _number_of_non_daemon_threads++; daemon = false; } ThreadService::add_thread(p, daemon); // Possible GC point. Events::log(p, "Thread added: " INTPTR_FORMAT, p); } void Threads::remove(JavaThread* p) { // Extra scope needed for Thread_lock, so we can check // that we do not remove thread without safepoint code notice { MutexLocker ml(Threads_lock); assert(includes(p), "p must be present"); JavaThread* current = _thread_list; JavaThread* prev = NULL; while (current != p) { prev = current; current = current->next(); } if (prev) { prev->set_next(current->next()); } else { _thread_list = p->next(); } _number_of_threads--; oop threadObj = p->threadObj(); bool daemon = true; if (threadObj == NULL || !java_lang_Thread::is_daemon(threadObj)) { _number_of_non_daemon_threads--; daemon = false; // Only one thread left, do a notify on the Threads_lock so a thread waiting // on destroy_vm will wake up. if (number_of_non_daemon_threads() == 1) Threads_lock->notify_all(); } ThreadService::remove_thread(p, daemon); // Make sure that safepoint code disregard this thread. This is needed since // the thread might mess around with locks after this point. This can cause it // to do callbacks into the safepoint code. However, the safepoint code is not aware // of this thread since it is removed from the queue. p->set_terminated_value(); } // unlock Threads_lock // Since Events::log uses a lock, we grab it outside the Threads_lock Events::log(p, "Thread exited: " INTPTR_FORMAT, p); } // Threads_lock must be held when this is called (or must be called during a safepoint) bool Threads::includes(JavaThread* p) { assert(Threads_lock->is_locked(), "sanity check"); ALL_JAVA_THREADS(q) { if (q == p ) { return true; } } return false; } // Operations on the Threads list for GC. These are not explicitly locked, // but the garbage collector must provide a safe context for them to run. // In particular, these things should never be called when the Threads_lock // is held by some other thread. (Note: the Safepoint abstraction also // uses the Threads_lock to gurantee this property. It also makes sure that // all threads gets blocked when exiting or starting). void Threads::oops_do(OopClosure* f, CLDClosure* cld_f, CodeBlobClosure* cf) { ALL_JAVA_THREADS(p) { p->oops_do(f, cld_f, cf); } VMThread::vm_thread()->oops_do(f, cld_f, cf); } void Threads::possibly_parallel_oops_do(OopClosure* f, CLDClosure* cld_f, CodeBlobClosure* cf) { // Introduce a mechanism allowing parallel threads to claim threads as // root groups. Overhead should be small enough to use all the time, // even in sequential code. SharedHeap* sh = SharedHeap::heap(); // Cannot yet substitute active_workers for n_par_threads // because of G1CollectedHeap::verify() use of // SharedHeap::process_roots(). n_par_threads == 0 will // turn off parallelism in process_roots while active_workers // is being used for parallelism elsewhere. bool is_par = sh->n_par_threads() > 0; assert(!is_par || (SharedHeap::heap()->n_par_threads() == SharedHeap::heap()->workers()->active_workers()), "Mismatch"); int cp = SharedHeap::heap()->strong_roots_parity(); ALL_JAVA_THREADS(p) { if (p->claim_oops_do(is_par, cp)) { p->oops_do(f, cld_f, cf); } } VMThread* vmt = VMThread::vm_thread(); if (vmt->claim_oops_do(is_par, cp)) { vmt->oops_do(f, cld_f, cf); } } #if INCLUDE_ALL_GCS // Used by ParallelScavenge void Threads::create_thread_roots_tasks(GCTaskQueue* q) { ALL_JAVA_THREADS(p) { q->enqueue(new ThreadRootsTask(p)); } q->enqueue(new ThreadRootsTask(VMThread::vm_thread())); } // Used by Parallel Old void Threads::create_thread_roots_marking_tasks(GCTaskQueue* q) { ALL_JAVA_THREADS(p) { q->enqueue(new ThreadRootsMarkingTask(p)); } q->enqueue(new ThreadRootsMarkingTask(VMThread::vm_thread())); } #endif // INCLUDE_ALL_GCS void Threads::nmethods_do(CodeBlobClosure* cf) { ALL_JAVA_THREADS(p) { p->nmethods_do(cf); } VMThread::vm_thread()->nmethods_do(cf); } void Threads::metadata_do(void f(Metadata*)) { ALL_JAVA_THREADS(p) { p->metadata_do(f); } } void Threads::gc_epilogue() { ALL_JAVA_THREADS(p) { p->gc_epilogue(); } } void Threads::gc_prologue() { ALL_JAVA_THREADS(p) { p->gc_prologue(); } } void Threads::deoptimized_wrt_marked_nmethods() { ALL_JAVA_THREADS(p) { p->deoptimized_wrt_marked_nmethods(); } } // Get count Java threads that are waiting to enter the specified monitor. GrowableArray* Threads::get_pending_threads(int count, address monitor, bool doLock) { assert(doLock || SafepointSynchronize::is_at_safepoint(), "must grab Threads_lock or be at safepoint"); GrowableArray* result = new GrowableArray(count); int i = 0; { MutexLockerEx ml(doLock ? Threads_lock : NULL); ALL_JAVA_THREADS(p) { if (p->is_Compiler_thread()) continue; address pending = (address)p->current_pending_monitor(); if (pending == monitor) { // found a match if (i < count) result->append(p); // save the first count matches i++; } } } return result; } JavaThread *Threads::owning_thread_from_monitor_owner(address owner, bool doLock) { assert(doLock || Threads_lock->owned_by_self() || SafepointSynchronize::is_at_safepoint(), "must grab Threads_lock or be at safepoint"); // NULL owner means not locked so we can skip the search if (owner == NULL) return NULL; { MutexLockerEx ml(doLock ? Threads_lock : NULL); ALL_JAVA_THREADS(p) { // first, see if owner is the address of a Java thread if (owner == (address)p) return p; } } // Cannot assert on lack of success here since this function may be // used by code that is trying to report useful problem information // like deadlock detection. if (UseHeavyMonitors) return NULL; // // If we didn't find a matching Java thread and we didn't force use of // heavyweight monitors, then the owner is the stack address of the // Lock Word in the owning Java thread's stack. // JavaThread* the_owner = NULL; { MutexLockerEx ml(doLock ? Threads_lock : NULL); ALL_JAVA_THREADS(q) { if (q->is_lock_owned(owner)) { the_owner = q; break; } } } // cannot assert on lack of success here; see above comment return the_owner; } // Threads::print_on() is called at safepoint by VM_PrintThreads operation. void Threads::print_on(outputStream* st, bool print_stacks, bool internal_format, bool print_concurrent_locks) { char buf[32]; st->print_cr("%s", os::local_time_string(buf, sizeof(buf))); st->print_cr("Full thread dump %s (%s %s):", Abstract_VM_Version::vm_name(), Abstract_VM_Version::vm_release(), Abstract_VM_Version::vm_info_string() ); st->cr(); #if INCLUDE_ALL_GCS // Dump concurrent locks ConcurrentLocksDump concurrent_locks; if (print_concurrent_locks) { concurrent_locks.dump_at_safepoint(); } #endif // INCLUDE_ALL_GCS ALL_JAVA_THREADS(p) { ResourceMark rm; p->print_on(st); if (print_stacks) { if (internal_format) { p->trace_stack(); } else { p->print_stack_on(st); } } st->cr(); #if INCLUDE_ALL_GCS if (print_concurrent_locks) { concurrent_locks.print_locks_on(p, st); } #endif // INCLUDE_ALL_GCS } VMThread::vm_thread()->print_on(st); st->cr(); Universe::heap()->print_gc_threads_on(st); WatcherThread* wt = WatcherThread::watcher_thread(); if (wt != NULL) { wt->print_on(st); st->cr(); } CompileBroker::print_compiler_threads_on(st); st->flush(); } // Threads::print_on_error() is called by fatal error handler. It's possible // that VM is not at safepoint and/or current thread is inside signal handler. // Don't print stack trace, as the stack may not be walkable. Don't allocate // memory (even in resource area), it might deadlock the error handler. void Threads::print_on_error(outputStream* st, Thread* current, char* buf, int buflen) { bool found_current = false; st->print_cr("Java Threads: ( => current thread )"); ALL_JAVA_THREADS(thread) { bool is_current = (current == thread); found_current = found_current || is_current; st->print("%s", is_current ? "=>" : " "); st->print(PTR_FORMAT, thread); st->print(" "); thread->print_on_error(st, buf, buflen); st->cr(); } st->cr(); st->print_cr("Other Threads:"); if (VMThread::vm_thread()) { bool is_current = (current == VMThread::vm_thread()); found_current = found_current || is_current; st->print("%s", current == VMThread::vm_thread() ? "=>" : " "); st->print(PTR_FORMAT, VMThread::vm_thread()); st->print(" "); VMThread::vm_thread()->print_on_error(st, buf, buflen); st->cr(); } WatcherThread* wt = WatcherThread::watcher_thread(); if (wt != NULL) { bool is_current = (current == wt); found_current = found_current || is_current; st->print("%s", is_current ? "=>" : " "); st->print(PTR_FORMAT, wt); st->print(" "); wt->print_on_error(st, buf, buflen); st->cr(); } if (!found_current) { st->cr(); st->print("=>" PTR_FORMAT " (exited) ", current); current->print_on_error(st, buf, buflen); st->cr(); } } // Internal SpinLock and Mutex // Based on ParkEvent // Ad-hoc mutual exclusion primitives: SpinLock and Mux // // We employ SpinLocks _only for low-contention, fixed-length // short-duration critical sections where we're concerned // about native mutex_t or HotSpot Mutex:: latency. // The mux construct provides a spin-then-block mutual exclusion // mechanism. // // Testing has shown that contention on the ListLock guarding gFreeList // is common. If we implement ListLock as a simple SpinLock it's common // for the JVM to devolve to yielding with little progress. This is true // despite the fact that the critical sections protected by ListLock are // extremely short. // // TODO-FIXME: ListLock should be of type SpinLock. // We should make this a 1st-class type, integrated into the lock // hierarchy as leaf-locks. Critically, the SpinLock structure // should have sufficient padding to avoid false-sharing and excessive // cache-coherency traffic. typedef volatile int SpinLockT ; void Thread::SpinAcquire (volatile int * adr, const char * LockName) { if (Atomic::cmpxchg (1, adr, 0) == 0) { return ; // normal fast-path return } // Slow-path : We've encountered contention -- Spin/Yield/Block strategy. TEVENT (SpinAcquire - ctx) ; int ctr = 0 ; int Yields = 0 ; for (;;) { while (*adr != 0) { ++ctr ; if ((ctr & 0xFFF) == 0 || !os::is_MP()) { if (Yields > 5) { os::naked_short_sleep(1); } else { os::NakedYield() ; ++Yields ; } } else { SpinPause() ; } } if (Atomic::cmpxchg (1, adr, 0) == 0) return ; } } void Thread::SpinRelease (volatile int * adr) { assert (*adr != 0, "invariant") ; OrderAccess::fence() ; // guarantee at least release consistency. // Roach-motel semantics. // It's safe if subsequent LDs and STs float "up" into the critical section, // but prior LDs and STs within the critical section can't be allowed // to reorder or float past the ST that releases the lock. *adr = 0 ; } // muxAcquire and muxRelease: // // * muxAcquire and muxRelease support a single-word lock-word construct. // The LSB of the word is set IFF the lock is held. // The remainder of the word points to the head of a singly-linked list // of threads blocked on the lock. // // * The current implementation of muxAcquire-muxRelease uses its own // dedicated Thread._MuxEvent instance. If we're interested in // minimizing the peak number of extant ParkEvent instances then // we could eliminate _MuxEvent and "borrow" _ParkEvent as long // as certain invariants were satisfied. Specifically, care would need // to be taken with regards to consuming unpark() "permits". // A safe rule of thumb is that a thread would never call muxAcquire() // if it's enqueued (cxq, EntryList, WaitList, etc) and will subsequently // park(). Otherwise the _ParkEvent park() operation in muxAcquire() could // consume an unpark() permit intended for monitorenter, for instance. // One way around this would be to widen the restricted-range semaphore // implemented in park(). Another alternative would be to provide // multiple instances of the PlatformEvent() for each thread. One // instance would be dedicated to muxAcquire-muxRelease, for instance. // // * Usage: // -- Only as leaf locks // -- for short-term locking only as muxAcquire does not perform // thread state transitions. // // Alternatives: // * We could implement muxAcquire and muxRelease with MCS or CLH locks // but with parking or spin-then-park instead of pure spinning. // * Use Taura-Oyama-Yonenzawa locks. // * It's possible to construct a 1-0 lock if we encode the lockword as // (List,LockByte). Acquire will CAS the full lockword while Release // will STB 0 into the LockByte. The 1-0 scheme admits stranding, so // acquiring threads use timers (ParkTimed) to detect and recover from // the stranding window. Thread/Node structures must be aligned on 256-byte // boundaries by using placement-new. // * Augment MCS with advisory back-link fields maintained with CAS(). // Pictorially: LockWord -> T1 <-> T2 <-> T3 <-> ... <-> Tn <-> Owner. // The validity of the backlinks must be ratified before we trust the value. // If the backlinks are invalid the exiting thread must back-track through the // the forward links, which are always trustworthy. // * Add a successor indication. The LockWord is currently encoded as // (List, LOCKBIT:1). We could also add a SUCCBIT or an explicit _succ variable // to provide the usual futile-wakeup optimization. // See RTStt for details. // * Consider schedctl.sc_nopreempt to cover the critical section. // typedef volatile intptr_t MutexT ; // Mux Lock-word enum MuxBits { LOCKBIT = 1 } ; void Thread::muxAcquire (volatile intptr_t * Lock, const char * LockName) { intptr_t w = Atomic::cmpxchg_ptr (LOCKBIT, Lock, 0) ; if (w == 0) return ; if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) { return ; } TEVENT (muxAcquire - Contention) ; ParkEvent * const Self = Thread::current()->_MuxEvent ; assert ((intptr_t(Self) & LOCKBIT) == 0, "invariant") ; for (;;) { int its = (os::is_MP() ? 100 : 0) + 1 ; // Optional spin phase: spin-then-park strategy while (--its >= 0) { w = *Lock ; if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) { return ; } } Self->reset() ; Self->OnList = intptr_t(Lock) ; // The following fence() isn't _strictly necessary as the subsequent // CAS() both serializes execution and ratifies the fetched *Lock value. OrderAccess::fence(); for (;;) { w = *Lock ; if ((w & LOCKBIT) == 0) { if (Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) { Self->OnList = 0 ; // hygiene - allows stronger asserts return ; } continue ; // Interference -- *Lock changed -- Just retry } assert (w & LOCKBIT, "invariant") ; Self->ListNext = (ParkEvent *) (w & ~LOCKBIT ); if (Atomic::cmpxchg_ptr (intptr_t(Self)|LOCKBIT, Lock, w) == w) break ; } while (Self->OnList != 0) { Self->park() ; } } } void Thread::muxAcquireW (volatile intptr_t * Lock, ParkEvent * ev) { intptr_t w = Atomic::cmpxchg_ptr (LOCKBIT, Lock, 0) ; if (w == 0) return ; if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) { return ; } TEVENT (muxAcquire - Contention) ; ParkEvent * ReleaseAfter = NULL ; if (ev == NULL) { ev = ReleaseAfter = ParkEvent::Allocate (NULL) ; } assert ((intptr_t(ev) & LOCKBIT) == 0, "invariant") ; for (;;) { guarantee (ev->OnList == 0, "invariant") ; int its = (os::is_MP() ? 100 : 0) + 1 ; // Optional spin phase: spin-then-park strategy while (--its >= 0) { w = *Lock ; if ((w & LOCKBIT) == 0 && Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) { if (ReleaseAfter != NULL) { ParkEvent::Release (ReleaseAfter) ; } return ; } } ev->reset() ; ev->OnList = intptr_t(Lock) ; // The following fence() isn't _strictly necessary as the subsequent // CAS() both serializes execution and ratifies the fetched *Lock value. OrderAccess::fence(); for (;;) { w = *Lock ; if ((w & LOCKBIT) == 0) { if (Atomic::cmpxchg_ptr (w|LOCKBIT, Lock, w) == w) { ev->OnList = 0 ; // We call ::Release while holding the outer lock, thus // artificially lengthening the critical section. // Consider deferring the ::Release() until the subsequent unlock(), // after we've dropped the outer lock. if (ReleaseAfter != NULL) { ParkEvent::Release (ReleaseAfter) ; } return ; } continue ; // Interference -- *Lock changed -- Just retry } assert (w & LOCKBIT, "invariant") ; ev->ListNext = (ParkEvent *) (w & ~LOCKBIT ); if (Atomic::cmpxchg_ptr (intptr_t(ev)|LOCKBIT, Lock, w) == w) break ; } while (ev->OnList != 0) { ev->park() ; } } } // Release() must extract a successor from the list and then wake that thread. // It can "pop" the front of the list or use a detach-modify-reattach (DMR) scheme // similar to that used by ParkEvent::Allocate() and ::Release(). DMR-based // Release() would : // (A) CAS() or swap() null to *Lock, releasing the lock and detaching the list. // (B) Extract a successor from the private list "in-hand" // (C) attempt to CAS() the residual back into *Lock over null. // If there were any newly arrived threads and the CAS() would fail. // In that case Release() would detach the RATs, re-merge the list in-hand // with the RATs and repeat as needed. Alternately, Release() might // detach and extract a successor, but then pass the residual list to the wakee. // The wakee would be responsible for reattaching and remerging before it // competed for the lock. // // Both "pop" and DMR are immune from ABA corruption -- there can be // multiple concurrent pushers, but only one popper or detacher. // This implementation pops from the head of the list. This is unfair, // but tends to provide excellent throughput as hot threads remain hot. // (We wake recently run threads first). void Thread::muxRelease (volatile intptr_t * Lock) { for (;;) { const intptr_t w = Atomic::cmpxchg_ptr (0, Lock, LOCKBIT) ; assert (w & LOCKBIT, "invariant") ; if (w == LOCKBIT) return ; ParkEvent * List = (ParkEvent *) (w & ~LOCKBIT) ; assert (List != NULL, "invariant") ; assert (List->OnList == intptr_t(Lock), "invariant") ; ParkEvent * nxt = List->ListNext ; // The following CAS() releases the lock and pops the head element. if (Atomic::cmpxchg_ptr (intptr_t(nxt), Lock, w) != w) { continue ; } List->OnList = 0 ; OrderAccess::fence() ; List->unpark () ; return ; } } void Threads::verify() { ALL_JAVA_THREADS(p) { p->verify(); } VMThread* thread = VMThread::vm_thread(); if (thread != NULL) thread->verify(); }