From 35abda9a60940de0fafd34976ce41d90f4b130a4 Mon Sep 17 00:00:00 2001 From: brutisso Date: Tue, 5 Jun 2012 22:30:24 +0200 Subject: [PATCH] 7172388: G1: _total_full_collections should not be incremented for concurrent cycles Reviewed-by: azeemj, jmasa --- .../g1/concurrentMarkThread.cpp | 2 +- .../gc_implementation/g1/g1CollectedHeap.cpp | 52 +++++++++++-------- .../gc_implementation/g1/g1CollectedHeap.hpp | 25 +++++---- .../gc_implementation/g1/vm_operations_g1.cpp | 20 +++---- .../gc_implementation/g1/vm_operations_g1.hpp | 2 +- 5 files changed, 57 insertions(+), 44 deletions(-) diff --git a/src/share/vm/gc_implementation/g1/concurrentMarkThread.cpp b/src/share/vm/gc_implementation/g1/concurrentMarkThread.cpp index 9959260d5..40d2aece1 100644 --- a/src/share/vm/gc_implementation/g1/concurrentMarkThread.cpp +++ b/src/share/vm/gc_implementation/g1/concurrentMarkThread.cpp @@ -293,7 +293,7 @@ void ConcurrentMarkThread::run() { // Java thread is waiting for a full GC to happen (e.g., it // called System.gc() with +ExplicitGCInvokesConcurrent). _sts.join(); - g1h->increment_full_collections_completed(true /* concurrent */); + g1h->increment_old_marking_cycles_completed(true /* concurrent */); _sts.leave(); } assert(_should_terminate, "just checking"); diff --git a/src/share/vm/gc_implementation/g1/g1CollectedHeap.cpp b/src/share/vm/gc_implementation/g1/g1CollectedHeap.cpp index 27863989e..2ee216b4d 100644 --- a/src/share/vm/gc_implementation/g1/g1CollectedHeap.cpp +++ b/src/share/vm/gc_implementation/g1/g1CollectedHeap.cpp @@ -1299,6 +1299,7 @@ bool G1CollectedHeap::do_collection(bool explicit_gc, gc_prologue(true); increment_total_collections(true /* full gc */); + increment_old_marking_cycles_started(); size_t g1h_prev_used = used(); assert(used() == recalculate_used(), "Should be equal"); @@ -1501,7 +1502,7 @@ bool G1CollectedHeap::do_collection(bool explicit_gc, "young list should be empty at this point"); // Update the number of full collections that have been completed. - increment_full_collections_completed(false /* concurrent */); + increment_old_marking_cycles_completed(false /* concurrent */); _hrs.verify_optional(); verify_region_sets_optional(); @@ -1888,7 +1889,8 @@ G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) : _retained_old_gc_alloc_region(NULL), _expand_heap_after_alloc_failure(true), _surviving_young_words(NULL), - _full_collections_completed(0), + _old_marking_cycles_started(0), + _old_marking_cycles_completed(0), _in_cset_fast_test(NULL), _in_cset_fast_test_base(NULL), _dirty_cards_region_list(NULL), @@ -2360,7 +2362,16 @@ void G1CollectedHeap::allocate_dummy_regions() { } #endif // !PRODUCT -void G1CollectedHeap::increment_full_collections_completed(bool concurrent) { +void G1CollectedHeap::increment_old_marking_cycles_started() { + assert(_old_marking_cycles_started == _old_marking_cycles_completed || + _old_marking_cycles_started == _old_marking_cycles_completed + 1, + err_msg("Wrong marking cycle count (started: %d, completed: %d)", + _old_marking_cycles_started, _old_marking_cycles_completed)); + + _old_marking_cycles_started++; +} + +void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) { MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag); // We assume that if concurrent == true, then the caller is a @@ -2368,11 +2379,6 @@ void G1CollectedHeap::increment_full_collections_completed(bool concurrent) { // Set. If there's ever a cheap way to check this, we should add an // assert here. - // We have already incremented _total_full_collections at the start - // of the GC, so total_full_collections() represents how many full - // collections have been started. - unsigned int full_collections_started = total_full_collections(); - // Given that this method is called at the end of a Full GC or of a // concurrent cycle, and those can be nested (i.e., a Full GC can // interrupt a concurrent cycle), the number of full collections @@ -2382,21 +2388,21 @@ void G1CollectedHeap::increment_full_collections_completed(bool concurrent) { // This is the case for the inner caller, i.e. a Full GC. assert(concurrent || - (full_collections_started == _full_collections_completed + 1) || - (full_collections_started == _full_collections_completed + 2), - err_msg("for inner caller (Full GC): full_collections_started = %u " - "is inconsistent with _full_collections_completed = %u", - full_collections_started, _full_collections_completed)); + (_old_marking_cycles_started == _old_marking_cycles_completed + 1) || + (_old_marking_cycles_started == _old_marking_cycles_completed + 2), + err_msg("for inner caller (Full GC): _old_marking_cycles_started = %u " + "is inconsistent with _old_marking_cycles_completed = %u", + _old_marking_cycles_started, _old_marking_cycles_completed)); // This is the case for the outer caller, i.e. the concurrent cycle. assert(!concurrent || - (full_collections_started == _full_collections_completed + 1), + (_old_marking_cycles_started == _old_marking_cycles_completed + 1), err_msg("for outer caller (concurrent cycle): " - "full_collections_started = %u " - "is inconsistent with _full_collections_completed = %u", - full_collections_started, _full_collections_completed)); + "_old_marking_cycles_started = %u " + "is inconsistent with _old_marking_cycles_completed = %u", + _old_marking_cycles_started, _old_marking_cycles_completed)); - _full_collections_completed += 1; + _old_marking_cycles_completed += 1; // We need to clear the "in_progress" flag in the CM thread before // we wake up any waiters (especially when ExplicitInvokesConcurrent @@ -2432,7 +2438,7 @@ void G1CollectedHeap::collect(GCCause::Cause cause) { assert_heap_not_locked(); unsigned int gc_count_before; - unsigned int full_gc_count_before; + unsigned int old_marking_count_before; bool retry_gc; do { @@ -2443,7 +2449,7 @@ void G1CollectedHeap::collect(GCCause::Cause cause) { // Read the GC count while holding the Heap_lock gc_count_before = total_collections(); - full_gc_count_before = total_full_collections(); + old_marking_count_before = _old_marking_cycles_started; } if (should_do_concurrent_full_gc(cause)) { @@ -2458,7 +2464,7 @@ void G1CollectedHeap::collect(GCCause::Cause cause) { VMThread::execute(&op); if (!op.pause_succeeded()) { - if (full_gc_count_before == total_full_collections()) { + if (old_marking_count_before == _old_marking_cycles_started) { retry_gc = op.should_retry_gc(); } else { // A Full GC happened while we were trying to schedule the @@ -2486,7 +2492,7 @@ void G1CollectedHeap::collect(GCCause::Cause cause) { VMThread::execute(&op); } else { // Schedule a Full GC. - VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause); + VM_G1CollectFull op(gc_count_before, old_marking_count_before, cause); VMThread::execute(&op); } } @@ -3613,7 +3619,7 @@ G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) { if (g1_policy()->during_initial_mark_pause()) { // We are about to start a marking cycle, so we increment the // full collection counter. - increment_total_full_collections(); + increment_old_marking_cycles_started(); } // if the log level is "finer" is on, we'll print long statistics information // in the collector policy code, so let's not print this as the output diff --git a/src/share/vm/gc_implementation/g1/g1CollectedHeap.hpp b/src/share/vm/gc_implementation/g1/g1CollectedHeap.hpp index 9b8e795c0..d3f5382d0 100644 --- a/src/share/vm/gc_implementation/g1/g1CollectedHeap.hpp +++ b/src/share/vm/gc_implementation/g1/g1CollectedHeap.hpp @@ -359,10 +359,13 @@ private: // (c) cause == _g1_humongous_allocation bool should_do_concurrent_full_gc(GCCause::Cause cause); - // Keeps track of how many "full collections" (i.e., Full GCs or - // concurrent cycles) we have completed. The number of them we have - // started is maintained in _total_full_collections in CollectedHeap. - volatile unsigned int _full_collections_completed; + // Keeps track of how many "old marking cycles" (i.e., Full GCs or + // concurrent cycles) we have started. + volatile unsigned int _old_marking_cycles_started; + + // Keeps track of how many "old marking cycles" (i.e., Full GCs or + // concurrent cycles) we have completed. + volatile unsigned int _old_marking_cycles_completed; // This is a non-product method that is helpful for testing. It is // called at the end of a GC and artificially expands the heap by @@ -673,8 +676,12 @@ public: (size_t) _in_cset_fast_test_length * sizeof(bool)); } + // This is called at the start of either a concurrent cycle or a Full + // GC to update the number of old marking cycles started. + void increment_old_marking_cycles_started(); + // This is called at the end of either a concurrent cycle or a Full - // GC to update the number of full collections completed. Those two + // GC to update the number of old marking cycles completed. Those two // can happen in a nested fashion, i.e., we start a concurrent // cycle, a Full GC happens half-way through it which ends first, // and then the cycle notices that a Full GC happened and ends @@ -683,14 +690,14 @@ public: // false, the caller is the inner caller in the nesting (i.e., the // Full GC). If concurrent is true, the caller is the outer caller // in this nesting (i.e., the concurrent cycle). Further nesting is - // not currently supported. The end of the this call also notifies + // not currently supported. The end of this call also notifies // the FullGCCount_lock in case a Java thread is waiting for a full // GC to happen (e.g., it called System.gc() with // +ExplicitGCInvokesConcurrent). - void increment_full_collections_completed(bool concurrent); + void increment_old_marking_cycles_completed(bool concurrent); - unsigned int full_collections_completed() { - return _full_collections_completed; + unsigned int old_marking_cycles_completed() { + return _old_marking_cycles_completed; } G1HRPrinter* hr_printer() { return &_hr_printer; } diff --git a/src/share/vm/gc_implementation/g1/vm_operations_g1.cpp b/src/share/vm/gc_implementation/g1/vm_operations_g1.cpp index d880f5509..cf7488ffe 100644 --- a/src/share/vm/gc_implementation/g1/vm_operations_g1.cpp +++ b/src/share/vm/gc_implementation/g1/vm_operations_g1.cpp @@ -64,7 +64,7 @@ VM_G1IncCollectionPause::VM_G1IncCollectionPause( _should_initiate_conc_mark(should_initiate_conc_mark), _target_pause_time_ms(target_pause_time_ms), _should_retry_gc(false), - _full_collections_completed_before(0) { + _old_marking_cycles_completed_before(0) { guarantee(target_pause_time_ms > 0.0, err_msg("target_pause_time_ms = %1.6lf should be positive", target_pause_time_ms)); @@ -112,11 +112,11 @@ void VM_G1IncCollectionPause::doit() { GCCauseSetter x(g1h, _gc_cause); if (_should_initiate_conc_mark) { - // It's safer to read full_collections_completed() here, given + // It's safer to read old_marking_cycles_completed() here, given // that noone else will be updating it concurrently. Since we'll // only need it if we're initiating a marking cycle, no point in // setting it earlier. - _full_collections_completed_before = g1h->full_collections_completed(); + _old_marking_cycles_completed_before = g1h->old_marking_cycles_completed(); // At this point we are supposed to start a concurrent cycle. We // will do so if one is not already in progress. @@ -181,17 +181,17 @@ void VM_G1IncCollectionPause::doit_epilogue() { G1CollectedHeap* g1h = G1CollectedHeap::heap(); - // In the doit() method we saved g1h->full_collections_completed() - // in the _full_collections_completed_before field. We have to - // wait until we observe that g1h->full_collections_completed() + // In the doit() method we saved g1h->old_marking_cycles_completed() + // in the _old_marking_cycles_completed_before field. We have to + // wait until we observe that g1h->old_marking_cycles_completed() // has increased by at least one. This can happen if a) we started // a cycle and it completes, b) a cycle already in progress // completes, or c) a Full GC happens. // If the condition has already been reached, there's no point in // actually taking the lock and doing the wait. - if (g1h->full_collections_completed() <= - _full_collections_completed_before) { + if (g1h->old_marking_cycles_completed() <= + _old_marking_cycles_completed_before) { // The following is largely copied from CMS Thread* thr = Thread::current(); @@ -200,8 +200,8 @@ void VM_G1IncCollectionPause::doit_epilogue() { ThreadToNativeFromVM native(jt); MutexLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag); - while (g1h->full_collections_completed() <= - _full_collections_completed_before) { + while (g1h->old_marking_cycles_completed() <= + _old_marking_cycles_completed_before) { FullGCCount_lock->wait(Mutex::_no_safepoint_check_flag); } } diff --git a/src/share/vm/gc_implementation/g1/vm_operations_g1.hpp b/src/share/vm/gc_implementation/g1/vm_operations_g1.hpp index ea2aeae21..691812e2e 100644 --- a/src/share/vm/gc_implementation/g1/vm_operations_g1.hpp +++ b/src/share/vm/gc_implementation/g1/vm_operations_g1.hpp @@ -80,7 +80,7 @@ private: bool _should_initiate_conc_mark; bool _should_retry_gc; double _target_pause_time_ms; - unsigned int _full_collections_completed_before; + unsigned int _old_marking_cycles_completed_before; public: VM_G1IncCollectionPause(unsigned int gc_count_before, size_t word_size, -- GitLab