/* * Copyright (c) 2001, 2012, 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 "gc_implementation/parallelScavenge/adjoiningGenerations.hpp" #include "gc_implementation/parallelScavenge/adjoiningVirtualSpaces.hpp" #include "gc_implementation/parallelScavenge/cardTableExtension.hpp" #include "gc_implementation/parallelScavenge/gcTaskManager.hpp" #include "gc_implementation/parallelScavenge/generationSizer.hpp" #include "gc_implementation/parallelScavenge/parallelScavengeHeap.inline.hpp" #include "gc_implementation/parallelScavenge/psAdaptiveSizePolicy.hpp" #include "gc_implementation/parallelScavenge/psMarkSweep.hpp" #include "gc_implementation/parallelScavenge/psParallelCompact.hpp" #include "gc_implementation/parallelScavenge/psPromotionManager.hpp" #include "gc_implementation/parallelScavenge/psScavenge.hpp" #include "gc_implementation/parallelScavenge/vmPSOperations.hpp" #include "memory/gcLocker.inline.hpp" #include "oops/oop.inline.hpp" #include "runtime/handles.inline.hpp" #include "runtime/java.hpp" #include "runtime/vmThread.hpp" #include "services/memTracker.hpp" #include "utilities/vmError.hpp" PSYoungGen* ParallelScavengeHeap::_young_gen = NULL; PSOldGen* ParallelScavengeHeap::_old_gen = NULL; PSAdaptiveSizePolicy* ParallelScavengeHeap::_size_policy = NULL; PSGCAdaptivePolicyCounters* ParallelScavengeHeap::_gc_policy_counters = NULL; ParallelScavengeHeap* ParallelScavengeHeap::_psh = NULL; GCTaskManager* ParallelScavengeHeap::_gc_task_manager = NULL; static void trace_gen_sizes(const char* const str, size_t og_min, size_t og_max, size_t yg_min, size_t yg_max) { if (TracePageSizes) { tty->print_cr("%s: " SIZE_FORMAT "," SIZE_FORMAT " " SIZE_FORMAT "," SIZE_FORMAT " " SIZE_FORMAT, str, og_min / K, og_max / K, yg_min / K, yg_max / K, (og_max + yg_max) / K); } } jint ParallelScavengeHeap::initialize() { CollectedHeap::pre_initialize(); // Cannot be initialized until after the flags are parsed // GenerationSizer flag_parser; _collector_policy = new GenerationSizer(); size_t yg_min_size = _collector_policy->min_young_gen_size(); size_t yg_max_size = _collector_policy->max_young_gen_size(); size_t og_min_size = _collector_policy->min_old_gen_size(); size_t og_max_size = _collector_policy->max_old_gen_size(); trace_gen_sizes("ps heap raw", og_min_size, og_max_size, yg_min_size, yg_max_size); const size_t og_page_sz = os::page_size_for_region(yg_min_size + og_min_size, yg_max_size + og_max_size, 8); const size_t og_align = set_alignment(_old_gen_alignment, og_page_sz); const size_t yg_align = set_alignment(_young_gen_alignment, og_page_sz); // Update sizes to reflect the selected page size(s). // // NEEDS_CLEANUP. The default TwoGenerationCollectorPolicy uses NewRatio; it // should check UseAdaptiveSizePolicy. Changes from generationSizer could // move to the common code. yg_min_size = align_size_up(yg_min_size, yg_align); yg_max_size = align_size_up(yg_max_size, yg_align); size_t yg_cur_size = align_size_up(_collector_policy->young_gen_size(), yg_align); yg_cur_size = MAX2(yg_cur_size, yg_min_size); og_min_size = align_size_up(og_min_size, og_align); // Align old gen size down to preserve specified heap size. assert(og_align == yg_align, "sanity"); og_max_size = align_size_down(og_max_size, og_align); og_max_size = MAX2(og_max_size, og_min_size); size_t og_cur_size = align_size_down(_collector_policy->old_gen_size(), og_align); og_cur_size = MAX2(og_cur_size, og_min_size); trace_gen_sizes("ps heap rnd", og_min_size, og_max_size, yg_min_size, yg_max_size); const size_t heap_size = og_max_size + yg_max_size; ReservedSpace heap_rs = Universe::reserve_heap(heap_size, og_align); MemTracker::record_virtual_memory_type((address)heap_rs.base(), mtJavaHeap); os::trace_page_sizes("ps main", og_min_size + yg_min_size, og_max_size + yg_max_size, og_page_sz, heap_rs.base(), heap_rs.size()); if (!heap_rs.is_reserved()) { vm_shutdown_during_initialization( "Could not reserve enough space for object heap"); return JNI_ENOMEM; } _reserved = MemRegion((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size())); CardTableExtension* const barrier_set = new CardTableExtension(_reserved, 3); _barrier_set = barrier_set; oopDesc::set_bs(_barrier_set); if (_barrier_set == NULL) { vm_shutdown_during_initialization( "Could not reserve enough space for barrier set"); return JNI_ENOMEM; } // Initial young gen size is 4 Mb // // XXX - what about flag_parser.young_gen_size()? const size_t init_young_size = align_size_up(4 * M, yg_align); yg_cur_size = MAX2(MIN2(init_young_size, yg_max_size), yg_cur_size); // Make up the generations // Calculate the maximum size that a generation can grow. This // includes growth into the other generation. Note that the // parameter _max_gen_size is kept as the maximum // size of the generation as the boundaries currently stand. // _max_gen_size is still used as that value. double max_gc_pause_sec = ((double) MaxGCPauseMillis)/1000.0; double max_gc_minor_pause_sec = ((double) MaxGCMinorPauseMillis)/1000.0; _gens = new AdjoiningGenerations(heap_rs, og_cur_size, og_min_size, og_max_size, yg_cur_size, yg_min_size, yg_max_size, yg_align); _old_gen = _gens->old_gen(); _young_gen = _gens->young_gen(); const size_t eden_capacity = _young_gen->eden_space()->capacity_in_bytes(); const size_t old_capacity = _old_gen->capacity_in_bytes(); const size_t initial_promo_size = MIN2(eden_capacity, old_capacity); _size_policy = new PSAdaptiveSizePolicy(eden_capacity, initial_promo_size, young_gen()->to_space()->capacity_in_bytes(), intra_heap_alignment(), max_gc_pause_sec, max_gc_minor_pause_sec, GCTimeRatio ); assert(!UseAdaptiveGCBoundary || (old_gen()->virtual_space()->high_boundary() == young_gen()->virtual_space()->low_boundary()), "Boundaries must meet"); // initialize the policy counters - 2 collectors, 3 generations _gc_policy_counters = new PSGCAdaptivePolicyCounters("ParScav:MSC", 2, 3, _size_policy); _psh = this; // Set up the GCTaskManager _gc_task_manager = GCTaskManager::create(ParallelGCThreads); if (UseParallelOldGC && !PSParallelCompact::initialize()) { return JNI_ENOMEM; } return JNI_OK; } void ParallelScavengeHeap::post_initialize() { // Need to init the tenuring threshold PSScavenge::initialize(); if (UseParallelOldGC) { PSParallelCompact::post_initialize(); } else { PSMarkSweep::initialize(); } PSPromotionManager::initialize(); } void ParallelScavengeHeap::update_counters() { young_gen()->update_counters(); old_gen()->update_counters(); MetaspaceCounters::update_performance_counters(); } size_t ParallelScavengeHeap::capacity() const { size_t value = young_gen()->capacity_in_bytes() + old_gen()->capacity_in_bytes(); return value; } size_t ParallelScavengeHeap::used() const { size_t value = young_gen()->used_in_bytes() + old_gen()->used_in_bytes(); return value; } bool ParallelScavengeHeap::is_maximal_no_gc() const { return old_gen()->is_maximal_no_gc() && young_gen()->is_maximal_no_gc(); } size_t ParallelScavengeHeap::max_capacity() const { size_t estimated = reserved_region().byte_size(); if (UseAdaptiveSizePolicy) { estimated -= _size_policy->max_survivor_size(young_gen()->max_size()); } else { estimated -= young_gen()->to_space()->capacity_in_bytes(); } return MAX2(estimated, capacity()); } bool ParallelScavengeHeap::is_in(const void* p) const { if (young_gen()->is_in(p)) { return true; } if (old_gen()->is_in(p)) { return true; } return false; } bool ParallelScavengeHeap::is_in_reserved(const void* p) const { if (young_gen()->is_in_reserved(p)) { return true; } if (old_gen()->is_in_reserved(p)) { return true; } return false; } bool ParallelScavengeHeap::is_scavengable(const void* addr) { return is_in_young((oop)addr); } #ifdef ASSERT // Don't implement this by using is_in_young(). This method is used // in some cases to check that is_in_young() is correct. bool ParallelScavengeHeap::is_in_partial_collection(const void *p) { assert(is_in_reserved(p) || p == NULL, "Does not work if address is non-null and outside of the heap"); // The order of the generations is old (low addr), young (high addr) return p >= old_gen()->reserved().end(); } #endif // There are two levels of allocation policy here. // // When an allocation request fails, the requesting thread must invoke a VM // operation, transfer control to the VM thread, and await the results of a // garbage collection. That is quite expensive, and we should avoid doing it // multiple times if possible. // // To accomplish this, we have a basic allocation policy, and also a // failed allocation policy. // // The basic allocation policy controls how you allocate memory without // attempting garbage collection. It is okay to grab locks and // expand the heap, if that can be done without coming to a safepoint. // It is likely that the basic allocation policy will not be very // aggressive. // // The failed allocation policy is invoked from the VM thread after // the basic allocation policy is unable to satisfy a mem_allocate // request. This policy needs to cover the entire range of collection, // heap expansion, and out-of-memory conditions. It should make every // attempt to allocate the requested memory. // Basic allocation policy. Should never be called at a safepoint, or // from the VM thread. // // This method must handle cases where many mem_allocate requests fail // simultaneously. When that happens, only one VM operation will succeed, // and the rest will not be executed. For that reason, this method loops // during failed allocation attempts. If the java heap becomes exhausted, // we rely on the size_policy object to force a bail out. HeapWord* ParallelScavengeHeap::mem_allocate( size_t size, bool* gc_overhead_limit_was_exceeded) { assert(!SafepointSynchronize::is_at_safepoint(), "should not be at safepoint"); assert(Thread::current() != (Thread*)VMThread::vm_thread(), "should not be in vm thread"); assert(!Heap_lock->owned_by_self(), "this thread should not own the Heap_lock"); // In general gc_overhead_limit_was_exceeded should be false so // set it so here and reset it to true only if the gc time // limit is being exceeded as checked below. *gc_overhead_limit_was_exceeded = false; HeapWord* result = young_gen()->allocate(size); uint loop_count = 0; uint gc_count = 0; int gclocker_stalled_count = 0; while (result == NULL) { // We don't want to have multiple collections for a single filled generation. // To prevent this, each thread tracks the total_collections() value, and if // the count has changed, does not do a new collection. // // The collection count must be read only while holding the heap lock. VM // operations also hold the heap lock during collections. There is a lock // contention case where thread A blocks waiting on the Heap_lock, while // thread B is holding it doing a collection. When thread A gets the lock, // the collection count has already changed. To prevent duplicate collections, // The policy MUST attempt allocations during the same period it reads the // total_collections() value! { MutexLocker ml(Heap_lock); gc_count = Universe::heap()->total_collections(); result = young_gen()->allocate(size); if (result != NULL) { return result; } // If certain conditions hold, try allocating from the old gen. result = mem_allocate_old_gen(size); if (result != NULL) { return result; } if (gclocker_stalled_count > GCLockerRetryAllocationCount) { return NULL; } // Failed to allocate without a gc. if (GC_locker::is_active_and_needs_gc()) { // If this thread is not in a jni critical section, we stall // the requestor until the critical section has cleared and // GC allowed. When the critical section clears, a GC is // initiated by the last thread exiting the critical section; so // we retry the allocation sequence from the beginning of the loop, // rather than causing more, now probably unnecessary, GC attempts. JavaThread* jthr = JavaThread::current(); if (!jthr->in_critical()) { MutexUnlocker mul(Heap_lock); GC_locker::stall_until_clear(); gclocker_stalled_count += 1; continue; } else { if (CheckJNICalls) { fatal("Possible deadlock due to allocating while" " in jni critical section"); } return NULL; } } } if (result == NULL) { // Generate a VM operation VM_ParallelGCFailedAllocation op(size, gc_count); VMThread::execute(&op); // Did the VM operation execute? If so, return the result directly. // This prevents us from looping until time out on requests that can // not be satisfied. if (op.prologue_succeeded()) { assert(Universe::heap()->is_in_or_null(op.result()), "result not in heap"); // If GC was locked out during VM operation then retry allocation // and/or stall as necessary. if (op.gc_locked()) { assert(op.result() == NULL, "must be NULL if gc_locked() is true"); continue; // retry and/or stall as necessary } // Exit the loop if the gc time limit has been exceeded. // The allocation must have failed above ("result" guarding // this path is NULL) and the most recent collection has exceeded the // gc overhead limit (although enough may have been collected to // satisfy the allocation). Exit the loop so that an out-of-memory // will be thrown (return a NULL ignoring the contents of // op.result()), // but clear gc_overhead_limit_exceeded so that the next collection // starts with a clean slate (i.e., forgets about previous overhead // excesses). Fill op.result() with a filler object so that the // heap remains parsable. const bool limit_exceeded = size_policy()->gc_overhead_limit_exceeded(); const bool softrefs_clear = collector_policy()->all_soft_refs_clear(); if (limit_exceeded && softrefs_clear) { *gc_overhead_limit_was_exceeded = true; size_policy()->set_gc_overhead_limit_exceeded(false); if (PrintGCDetails && Verbose) { gclog_or_tty->print_cr("ParallelScavengeHeap::mem_allocate: " "return NULL because gc_overhead_limit_exceeded is set"); } if (op.result() != NULL) { CollectedHeap::fill_with_object(op.result(), size); } return NULL; } return op.result(); } } // The policy object will prevent us from looping forever. If the // time spent in gc crosses a threshold, we will bail out. loop_count++; if ((result == NULL) && (QueuedAllocationWarningCount > 0) && (loop_count % QueuedAllocationWarningCount == 0)) { warning("ParallelScavengeHeap::mem_allocate retries %d times \n\t" " size=%d", loop_count, size); } } return result; } // A "death march" is a series of ultra-slow allocations in which a full gc is // done before each allocation, and after the full gc the allocation still // cannot be satisfied from the young gen. This routine detects that condition; // it should be called after a full gc has been done and the allocation // attempted from the young gen. The parameter 'addr' should be the result of // that young gen allocation attempt. void ParallelScavengeHeap::death_march_check(HeapWord* const addr, size_t size) { if (addr != NULL) { _death_march_count = 0; // death march has ended } else if (_death_march_count == 0) { if (should_alloc_in_eden(size)) { _death_march_count = 1; // death march has started } } } HeapWord* ParallelScavengeHeap::mem_allocate_old_gen(size_t size) { if (!should_alloc_in_eden(size) || GC_locker::is_active_and_needs_gc()) { // Size is too big for eden, or gc is locked out. return old_gen()->allocate(size); } // If a "death march" is in progress, allocate from the old gen a limited // number of times before doing a GC. if (_death_march_count > 0) { if (_death_march_count < 64) { ++_death_march_count; return old_gen()->allocate(size); } else { _death_march_count = 0; } } return NULL; } void ParallelScavengeHeap::do_full_collection(bool clear_all_soft_refs) { if (UseParallelOldGC) { // The do_full_collection() parameter clear_all_soft_refs // is interpreted here as maximum_compaction which will // cause SoftRefs to be cleared. bool maximum_compaction = clear_all_soft_refs; PSParallelCompact::invoke(maximum_compaction); } else { PSMarkSweep::invoke(clear_all_soft_refs); } } // Failed allocation policy. Must be called from the VM thread, and // only at a safepoint! Note that this method has policy for allocation // flow, and NOT collection policy. So we do not check for gc collection // time over limit here, that is the responsibility of the heap specific // collection methods. This method decides where to attempt allocations, // and when to attempt collections, but no collection specific policy. HeapWord* ParallelScavengeHeap::failed_mem_allocate(size_t size) { assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint"); assert(Thread::current() == (Thread*)VMThread::vm_thread(), "should be in vm thread"); assert(!Universe::heap()->is_gc_active(), "not reentrant"); assert(!Heap_lock->owned_by_self(), "this thread should not own the Heap_lock"); // We assume that allocation in eden will fail unless we collect. // First level allocation failure, scavenge and allocate in young gen. GCCauseSetter gccs(this, GCCause::_allocation_failure); const bool invoked_full_gc = PSScavenge::invoke(); HeapWord* result = young_gen()->allocate(size); // Second level allocation failure. // Mark sweep and allocate in young generation. if (result == NULL && !invoked_full_gc) { do_full_collection(false); result = young_gen()->allocate(size); } death_march_check(result, size); // Third level allocation failure. // After mark sweep and young generation allocation failure, // allocate in old generation. if (result == NULL) { result = old_gen()->allocate(size); } // Fourth level allocation failure. We're running out of memory. // More complete mark sweep and allocate in young generation. if (result == NULL) { do_full_collection(true); result = young_gen()->allocate(size); } // Fifth level allocation failure. // After more complete mark sweep, allocate in old generation. if (result == NULL) { result = old_gen()->allocate(size); } return result; } void ParallelScavengeHeap::ensure_parsability(bool retire_tlabs) { CollectedHeap::ensure_parsability(retire_tlabs); young_gen()->eden_space()->ensure_parsability(); } size_t ParallelScavengeHeap::unsafe_max_alloc() { return young_gen()->eden_space()->free_in_bytes(); } size_t ParallelScavengeHeap::tlab_capacity(Thread* thr) const { return young_gen()->eden_space()->tlab_capacity(thr); } size_t ParallelScavengeHeap::unsafe_max_tlab_alloc(Thread* thr) const { return young_gen()->eden_space()->unsafe_max_tlab_alloc(thr); } HeapWord* ParallelScavengeHeap::allocate_new_tlab(size_t size) { return young_gen()->allocate(size); } void ParallelScavengeHeap::accumulate_statistics_all_tlabs() { CollectedHeap::accumulate_statistics_all_tlabs(); } void ParallelScavengeHeap::resize_all_tlabs() { CollectedHeap::resize_all_tlabs(); } bool ParallelScavengeHeap::can_elide_initializing_store_barrier(oop new_obj) { // We don't need barriers for stores to objects in the // young gen and, a fortiori, for initializing stores to // objects therein. return is_in_young(new_obj); } // This method is used by System.gc() and JVMTI. void ParallelScavengeHeap::collect(GCCause::Cause cause) { assert(!Heap_lock->owned_by_self(), "this thread should not own the Heap_lock"); unsigned int gc_count = 0; unsigned int full_gc_count = 0; { MutexLocker ml(Heap_lock); // This value is guarded by the Heap_lock gc_count = Universe::heap()->total_collections(); full_gc_count = Universe::heap()->total_full_collections(); } VM_ParallelGCSystemGC op(gc_count, full_gc_count, cause); VMThread::execute(&op); } void ParallelScavengeHeap::oop_iterate(ExtendedOopClosure* cl) { Unimplemented(); } void ParallelScavengeHeap::object_iterate(ObjectClosure* cl) { young_gen()->object_iterate(cl); old_gen()->object_iterate(cl); } HeapWord* ParallelScavengeHeap::block_start(const void* addr) const { if (young_gen()->is_in_reserved(addr)) { assert(young_gen()->is_in(addr), "addr should be in allocated part of young gen"); // called from os::print_location by find or VMError if (Debugging || VMError::fatal_error_in_progress()) return NULL; Unimplemented(); } else if (old_gen()->is_in_reserved(addr)) { assert(old_gen()->is_in(addr), "addr should be in allocated part of old gen"); return old_gen()->start_array()->object_start((HeapWord*)addr); } return 0; } size_t ParallelScavengeHeap::block_size(const HeapWord* addr) const { return oop(addr)->size(); } bool ParallelScavengeHeap::block_is_obj(const HeapWord* addr) const { return block_start(addr) == addr; } jlong ParallelScavengeHeap::millis_since_last_gc() { return UseParallelOldGC ? PSParallelCompact::millis_since_last_gc() : PSMarkSweep::millis_since_last_gc(); } void ParallelScavengeHeap::prepare_for_verify() { ensure_parsability(false); // no need to retire TLABs for verification } void ParallelScavengeHeap::print_on(outputStream* st) const { young_gen()->print_on(st); old_gen()->print_on(st); MetaspaceAux::print_on(st); } void ParallelScavengeHeap::gc_threads_do(ThreadClosure* tc) const { PSScavenge::gc_task_manager()->threads_do(tc); } void ParallelScavengeHeap::print_gc_threads_on(outputStream* st) const { PSScavenge::gc_task_manager()->print_threads_on(st); } void ParallelScavengeHeap::print_tracing_info() const { if (TraceGen0Time) { double time = PSScavenge::accumulated_time()->seconds(); tty->print_cr("[Accumulated GC generation 0 time %3.7f secs]", time); } if (TraceGen1Time) { double time = UseParallelOldGC ? PSParallelCompact::accumulated_time()->seconds() : PSMarkSweep::accumulated_time()->seconds(); tty->print_cr("[Accumulated GC generation 1 time %3.7f secs]", time); } } void ParallelScavengeHeap::verify(bool silent, VerifyOption option /* ignored */) { // Why do we need the total_collections()-filter below? if (total_collections() > 0) { if (!silent) { gclog_or_tty->print("tenured "); } old_gen()->verify(); if (!silent) { gclog_or_tty->print("eden "); } young_gen()->verify(); } } void ParallelScavengeHeap::print_heap_change(size_t prev_used) { if (PrintGCDetails && Verbose) { gclog_or_tty->print(" " SIZE_FORMAT "->" SIZE_FORMAT "(" SIZE_FORMAT ")", prev_used, used(), capacity()); } else { gclog_or_tty->print(" " SIZE_FORMAT "K" "->" SIZE_FORMAT "K" "(" SIZE_FORMAT "K)", prev_used / K, used() / K, capacity() / K); } } ParallelScavengeHeap* ParallelScavengeHeap::heap() { assert(_psh != NULL, "Uninitialized access to ParallelScavengeHeap::heap()"); assert(_psh->kind() == CollectedHeap::ParallelScavengeHeap, "not a parallel scavenge heap"); return _psh; } // Before delegating the resize to the young generation, // the reserved space for the young and old generations // may be changed to accomodate the desired resize. void ParallelScavengeHeap::resize_young_gen(size_t eden_size, size_t survivor_size) { if (UseAdaptiveGCBoundary) { if (size_policy()->bytes_absorbed_from_eden() != 0) { size_policy()->reset_bytes_absorbed_from_eden(); return; // The generation changed size already. } gens()->adjust_boundary_for_young_gen_needs(eden_size, survivor_size); } // Delegate the resize to the generation. _young_gen->resize(eden_size, survivor_size); } // Before delegating the resize to the old generation, // the reserved space for the young and old generations // may be changed to accomodate the desired resize. void ParallelScavengeHeap::resize_old_gen(size_t desired_free_space) { if (UseAdaptiveGCBoundary) { if (size_policy()->bytes_absorbed_from_eden() != 0) { size_policy()->reset_bytes_absorbed_from_eden(); return; // The generation changed size already. } gens()->adjust_boundary_for_old_gen_needs(desired_free_space); } // Delegate the resize to the generation. _old_gen->resize(desired_free_space); } ParallelScavengeHeap::ParStrongRootsScope::ParStrongRootsScope() { // nothing particular } ParallelScavengeHeap::ParStrongRootsScope::~ParStrongRootsScope() { // nothing particular } #ifndef PRODUCT void ParallelScavengeHeap::record_gen_tops_before_GC() { if (ZapUnusedHeapArea) { young_gen()->record_spaces_top(); old_gen()->record_spaces_top(); } } void ParallelScavengeHeap::gen_mangle_unused_area() { if (ZapUnusedHeapArea) { young_gen()->eden_space()->mangle_unused_area(); young_gen()->to_space()->mangle_unused_area(); young_gen()->from_space()->mangle_unused_area(); old_gen()->object_space()->mangle_unused_area(); } } #endif