--- old/src/share/vm/gc_implementation/concurrentMarkSweep/vmCMSOperations.cpp 2015-05-12 11:38:35.695063667 +0200 +++ /dev/null 2015-03-18 17:10:38.111854831 +0100 @@ -1,275 +0,0 @@ -/* - * Copyright (c) 2005, 2015, 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/concurrentMarkSweep/concurrentMarkSweepGeneration.inline.hpp" -#include "gc_implementation/concurrentMarkSweep/concurrentMarkSweepThread.hpp" -#include "gc_implementation/concurrentMarkSweep/vmCMSOperations.hpp" -#include "gc_implementation/shared/gcTimer.hpp" -#include "gc_implementation/shared/gcTraceTime.hpp" -#include "gc_implementation/shared/isGCActiveMark.hpp" -#include "memory/gcLocker.inline.hpp" -#include "runtime/interfaceSupport.hpp" -#include "runtime/os.hpp" -#include "utilities/dtrace.hpp" - -////////////////////////////////////////////////////////// -// Methods in abstract class VM_CMS_Operation -////////////////////////////////////////////////////////// -void VM_CMS_Operation::acquire_pending_list_lock() { - // The caller may block while communicating - // with the SLT thread in order to acquire/release the PLL. - SurrogateLockerThread* slt = ConcurrentMarkSweepThread::slt(); - if (slt != NULL) { - slt->manipulatePLL(SurrogateLockerThread::acquirePLL); - } else { - SurrogateLockerThread::report_missing_slt(); - } -} - -void VM_CMS_Operation::release_and_notify_pending_list_lock() { - // The caller may block while communicating - // with the SLT thread in order to acquire/release the PLL. - ConcurrentMarkSweepThread::slt()-> - manipulatePLL(SurrogateLockerThread::releaseAndNotifyPLL); -} - -void VM_CMS_Operation::verify_before_gc() { - if (VerifyBeforeGC && - GenCollectedHeap::heap()->total_collections() >= VerifyGCStartAt) { - GCTraceTime tm("Verify Before", false, false, _collector->_gc_timer_cm, _collector->_gc_tracer_cm->gc_id()); - HandleMark hm; - FreelistLocker x(_collector); - MutexLockerEx y(_collector->bitMapLock(), Mutex::_no_safepoint_check_flag); - GenCollectedHeap::heap()->prepare_for_verify(); - Universe::verify(); - } -} - -void VM_CMS_Operation::verify_after_gc() { - if (VerifyAfterGC && - GenCollectedHeap::heap()->total_collections() >= VerifyGCStartAt) { - GCTraceTime tm("Verify After", false, false, _collector->_gc_timer_cm, _collector->_gc_tracer_cm->gc_id()); - HandleMark hm; - FreelistLocker x(_collector); - MutexLockerEx y(_collector->bitMapLock(), Mutex::_no_safepoint_check_flag); - Universe::verify(); - } -} - -bool VM_CMS_Operation::lost_race() const { - if (CMSCollector::abstract_state() == CMSCollector::Idling) { - // We lost a race to a foreground collection - // -- there's nothing to do - return true; - } - assert(CMSCollector::abstract_state() == legal_state(), - "Inconsistent collector state?"); - return false; -} - -bool VM_CMS_Operation::doit_prologue() { - assert(Thread::current()->is_ConcurrentGC_thread(), "just checking"); - assert(!CMSCollector::foregroundGCShouldWait(), "Possible deadlock"); - assert(!ConcurrentMarkSweepThread::cms_thread_has_cms_token(), - "Possible deadlock"); - - if (needs_pll()) { - acquire_pending_list_lock(); - } - // Get the Heap_lock after the pending_list_lock. - Heap_lock->lock(); - if (lost_race()) { - assert(_prologue_succeeded == false, "Initialized in c'tor"); - Heap_lock->unlock(); - if (needs_pll()) { - release_and_notify_pending_list_lock(); - } - } else { - _prologue_succeeded = true; - } - return _prologue_succeeded; -} - -void VM_CMS_Operation::doit_epilogue() { - assert(Thread::current()->is_ConcurrentGC_thread(), "just checking"); - assert(!CMSCollector::foregroundGCShouldWait(), "Possible deadlock"); - assert(!ConcurrentMarkSweepThread::cms_thread_has_cms_token(), - "Possible deadlock"); - - // Release the Heap_lock first. - Heap_lock->unlock(); - if (needs_pll()) { - release_and_notify_pending_list_lock(); - } -} - -////////////////////////////////////////////////////////// -// Methods in class VM_CMS_Initial_Mark -////////////////////////////////////////////////////////// -void VM_CMS_Initial_Mark::doit() { - if (lost_race()) { - // Nothing to do. - return; - } - HS_PRIVATE_CMS_INITMARK_BEGIN(); - - _collector->_gc_timer_cm->register_gc_pause_start("Initial Mark"); - - GenCollectedHeap* gch = GenCollectedHeap::heap(); - GCCauseSetter gccs(gch, GCCause::_cms_initial_mark); - - VM_CMS_Operation::verify_before_gc(); - - IsGCActiveMark x; // stop-world GC active - _collector->do_CMS_operation(CMSCollector::CMS_op_checkpointRootsInitial, gch->gc_cause()); - - VM_CMS_Operation::verify_after_gc(); - - _collector->_gc_timer_cm->register_gc_pause_end(); - - HS_PRIVATE_CMS_INITMARK_END(); -} - -////////////////////////////////////////////////////////// -// Methods in class VM_CMS_Final_Remark_Operation -////////////////////////////////////////////////////////// -void VM_CMS_Final_Remark::doit() { - if (lost_race()) { - // Nothing to do. - return; - } - HS_PRIVATE_CMS_REMARK_BEGIN(); - - _collector->_gc_timer_cm->register_gc_pause_start("Final Mark"); - - GenCollectedHeap* gch = GenCollectedHeap::heap(); - GCCauseSetter gccs(gch, GCCause::_cms_final_remark); - - VM_CMS_Operation::verify_before_gc(); - - IsGCActiveMark x; // stop-world GC active - _collector->do_CMS_operation(CMSCollector::CMS_op_checkpointRootsFinal, gch->gc_cause()); - - VM_CMS_Operation::verify_after_gc(); - - _collector->save_heap_summary(); - _collector->_gc_timer_cm->register_gc_pause_end(); - - HS_PRIVATE_CMS_REMARK_END(); -} - -// VM operation to invoke a concurrent collection of a -// GenCollectedHeap heap. -void VM_GenCollectFullConcurrent::doit() { - assert(Thread::current()->is_VM_thread(), "Should be VM thread"); - assert(GCLockerInvokesConcurrent || ExplicitGCInvokesConcurrent, "Unexpected"); - - GenCollectedHeap* gch = GenCollectedHeap::heap(); - if (_gc_count_before == gch->total_collections()) { - // The "full" of do_full_collection call below "forces" - // a collection; the second arg, 0, below ensures that - // only the young gen is collected. XXX In the future, - // we'll probably need to have something in this interface - // to say do this only if we are sure we will not bail - // out to a full collection in this attempt, but that's - // for the future. - assert(SafepointSynchronize::is_at_safepoint(), - "We can only be executing this arm of if at a safepoint"); - GCCauseSetter gccs(gch, _gc_cause); - gch->do_full_collection(gch->must_clear_all_soft_refs(), - 0 /* collect only youngest gen */); - } // Else no need for a foreground young gc - assert((_gc_count_before < gch->total_collections()) || - (GC_locker::is_active() /* gc may have been skipped */ - && (_gc_count_before == gch->total_collections())), - "total_collections() should be monotonically increasing"); - - MutexLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag); - assert(_full_gc_count_before <= gch->total_full_collections(), "Error"); - if (gch->total_full_collections() == _full_gc_count_before) { - // Nudge the CMS thread to start a concurrent collection. - CMSCollector::request_full_gc(_full_gc_count_before, _gc_cause); - } else { - assert(_full_gc_count_before < gch->total_full_collections(), "Error"); - FullGCCount_lock->notify_all(); // Inform the Java thread its work is done - } -} - -bool VM_GenCollectFullConcurrent::evaluate_at_safepoint() const { - Thread* thr = Thread::current(); - assert(thr != NULL, "Unexpected tid"); - if (!thr->is_Java_thread()) { - assert(thr->is_VM_thread(), "Expected to be evaluated by VM thread"); - GenCollectedHeap* gch = GenCollectedHeap::heap(); - if (_gc_count_before != gch->total_collections()) { - // No need to do a young gc, we'll just nudge the CMS thread - // in the doit() method above, to be executed soon. - assert(_gc_count_before < gch->total_collections(), - "total_collections() should be monotonically increasing"); - return false; // no need for foreground young gc - } - } - return true; // may still need foreground young gc -} - - -void VM_GenCollectFullConcurrent::doit_epilogue() { - Thread* thr = Thread::current(); - assert(thr->is_Java_thread(), "just checking"); - JavaThread* jt = (JavaThread*)thr; - // Release the Heap_lock first. - Heap_lock->unlock(); - release_and_notify_pending_list_lock(); - - // It is fine to test whether completed collections has - // exceeded our request count without locking because - // the completion count is monotonically increasing; - // this will break for very long-running apps when the - // count overflows and wraps around. XXX fix me !!! - // e.g. at the rate of 1 full gc per ms, this could - // overflow in about 1000 years. - GenCollectedHeap* gch = GenCollectedHeap::heap(); - if (_gc_cause != GCCause::_gc_locker && - gch->total_full_collections_completed() <= _full_gc_count_before) { - // maybe we should change the condition to test _gc_cause == - // GCCause::_java_lang_system_gc, instead of - // _gc_cause != GCCause::_gc_locker - assert(_gc_cause == GCCause::_java_lang_system_gc, - "the only way to get here if this was a System.gc()-induced GC"); - assert(ExplicitGCInvokesConcurrent, "Error"); - // Now, wait for witnessing concurrent gc cycle to complete, - // but do so in native mode, because we want to lock the - // FullGCEvent_lock, which may be needed by the VM thread - // or by the CMS thread, so we do not want to be suspended - // while holding that lock. - ThreadToNativeFromVM native(jt); - MutexLockerEx ml(FullGCCount_lock, Mutex::_no_safepoint_check_flag); - // Either a concurrent or a stop-world full gc is sufficient - // witness to our request. - while (gch->total_full_collections_completed() <= _full_gc_count_before) { - FullGCCount_lock->wait(Mutex::_no_safepoint_check_flag); - } - } -} --- /dev/null 2015-03-18 17:10:38.111854831 +0100 +++ new/src/share/vm/gc/cms/vmCMSOperations.cpp 2015-05-12 11:38:35.441053087 +0200 @@ -0,0 +1,275 @@ +/* + * Copyright (c) 2005, 2015, 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/cms/concurrentMarkSweepGeneration.inline.hpp" +#include "gc/cms/concurrentMarkSweepThread.hpp" +#include "gc/cms/vmCMSOperations.hpp" +#include "gc/shared/gcLocker.inline.hpp" +#include "gc/shared/gcTimer.hpp" +#include "gc/shared/gcTraceTime.hpp" +#include "gc/shared/isGCActiveMark.hpp" +#include "runtime/interfaceSupport.hpp" +#include "runtime/os.hpp" +#include "utilities/dtrace.hpp" + +////////////////////////////////////////////////////////// +// Methods in abstract class VM_CMS_Operation +////////////////////////////////////////////////////////// +void VM_CMS_Operation::acquire_pending_list_lock() { + // The caller may block while communicating + // with the SLT thread in order to acquire/release the PLL. + SurrogateLockerThread* slt = ConcurrentMarkSweepThread::slt(); + if (slt != NULL) { + slt->manipulatePLL(SurrogateLockerThread::acquirePLL); + } else { + SurrogateLockerThread::report_missing_slt(); + } +} + +void VM_CMS_Operation::release_and_notify_pending_list_lock() { + // The caller may block while communicating + // with the SLT thread in order to acquire/release the PLL. + ConcurrentMarkSweepThread::slt()-> + manipulatePLL(SurrogateLockerThread::releaseAndNotifyPLL); +} + +void VM_CMS_Operation::verify_before_gc() { + if (VerifyBeforeGC && + GenCollectedHeap::heap()->total_collections() >= VerifyGCStartAt) { + GCTraceTime tm("Verify Before", false, false, _collector->_gc_timer_cm, _collector->_gc_tracer_cm->gc_id()); + HandleMark hm; + FreelistLocker x(_collector); + MutexLockerEx y(_collector->bitMapLock(), Mutex::_no_safepoint_check_flag); + GenCollectedHeap::heap()->prepare_for_verify(); + Universe::verify(); + } +} + +void VM_CMS_Operation::verify_after_gc() { + if (VerifyAfterGC && + GenCollectedHeap::heap()->total_collections() >= VerifyGCStartAt) { + GCTraceTime tm("Verify After", false, false, _collector->_gc_timer_cm, _collector->_gc_tracer_cm->gc_id()); + HandleMark hm; + FreelistLocker x(_collector); + MutexLockerEx y(_collector->bitMapLock(), Mutex::_no_safepoint_check_flag); + Universe::verify(); + } +} + +bool VM_CMS_Operation::lost_race() const { + if (CMSCollector::abstract_state() == CMSCollector::Idling) { + // We lost a race to a foreground collection + // -- there's nothing to do + return true; + } + assert(CMSCollector::abstract_state() == legal_state(), + "Inconsistent collector state?"); + return false; +} + +bool VM_CMS_Operation::doit_prologue() { + assert(Thread::current()->is_ConcurrentGC_thread(), "just checking"); + assert(!CMSCollector::foregroundGCShouldWait(), "Possible deadlock"); + assert(!ConcurrentMarkSweepThread::cms_thread_has_cms_token(), + "Possible deadlock"); + + if (needs_pll()) { + acquire_pending_list_lock(); + } + // Get the Heap_lock after the pending_list_lock. + Heap_lock->lock(); + if (lost_race()) { + assert(_prologue_succeeded == false, "Initialized in c'tor"); + Heap_lock->unlock(); + if (needs_pll()) { + release_and_notify_pending_list_lock(); + } + } else { + _prologue_succeeded = true; + } + return _prologue_succeeded; +} + +void VM_CMS_Operation::doit_epilogue() { + assert(Thread::current()->is_ConcurrentGC_thread(), "just checking"); + assert(!CMSCollector::foregroundGCShouldWait(), "Possible deadlock"); + assert(!ConcurrentMarkSweepThread::cms_thread_has_cms_token(), + "Possible deadlock"); + + // Release the Heap_lock first. + Heap_lock->unlock(); + if (needs_pll()) { + release_and_notify_pending_list_lock(); + } +} + +////////////////////////////////////////////////////////// +// Methods in class VM_CMS_Initial_Mark +////////////////////////////////////////////////////////// +void VM_CMS_Initial_Mark::doit() { + if (lost_race()) { + // Nothing to do. + return; + } + HS_PRIVATE_CMS_INITMARK_BEGIN(); + + _collector->_gc_timer_cm->register_gc_pause_start("Initial Mark"); + + GenCollectedHeap* gch = GenCollectedHeap::heap(); + GCCauseSetter gccs(gch, GCCause::_cms_initial_mark); + + VM_CMS_Operation::verify_before_gc(); + + IsGCActiveMark x; // stop-world GC active + _collector->do_CMS_operation(CMSCollector::CMS_op_checkpointRootsInitial, gch->gc_cause()); + + VM_CMS_Operation::verify_after_gc(); + + _collector->_gc_timer_cm->register_gc_pause_end(); + + HS_PRIVATE_CMS_INITMARK_END(); +} + +////////////////////////////////////////////////////////// +// Methods in class VM_CMS_Final_Remark_Operation +////////////////////////////////////////////////////////// +void VM_CMS_Final_Remark::doit() { + if (lost_race()) { + // Nothing to do. + return; + } + HS_PRIVATE_CMS_REMARK_BEGIN(); + + _collector->_gc_timer_cm->register_gc_pause_start("Final Mark"); + + GenCollectedHeap* gch = GenCollectedHeap::heap(); + GCCauseSetter gccs(gch, GCCause::_cms_final_remark); + + VM_CMS_Operation::verify_before_gc(); + + IsGCActiveMark x; // stop-world GC active + _collector->do_CMS_operation(CMSCollector::CMS_op_checkpointRootsFinal, gch->gc_cause()); + + VM_CMS_Operation::verify_after_gc(); + + _collector->save_heap_summary(); + _collector->_gc_timer_cm->register_gc_pause_end(); + + HS_PRIVATE_CMS_REMARK_END(); +} + +// VM operation to invoke a concurrent collection of a +// GenCollectedHeap heap. +void VM_GenCollectFullConcurrent::doit() { + assert(Thread::current()->is_VM_thread(), "Should be VM thread"); + assert(GCLockerInvokesConcurrent || ExplicitGCInvokesConcurrent, "Unexpected"); + + GenCollectedHeap* gch = GenCollectedHeap::heap(); + if (_gc_count_before == gch->total_collections()) { + // The "full" of do_full_collection call below "forces" + // a collection; the second arg, 0, below ensures that + // only the young gen is collected. XXX In the future, + // we'll probably need to have something in this interface + // to say do this only if we are sure we will not bail + // out to a full collection in this attempt, but that's + // for the future. + assert(SafepointSynchronize::is_at_safepoint(), + "We can only be executing this arm of if at a safepoint"); + GCCauseSetter gccs(gch, _gc_cause); + gch->do_full_collection(gch->must_clear_all_soft_refs(), + 0 /* collect only youngest gen */); + } // Else no need for a foreground young gc + assert((_gc_count_before < gch->total_collections()) || + (GC_locker::is_active() /* gc may have been skipped */ + && (_gc_count_before == gch->total_collections())), + "total_collections() should be monotonically increasing"); + + MutexLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag); + assert(_full_gc_count_before <= gch->total_full_collections(), "Error"); + if (gch->total_full_collections() == _full_gc_count_before) { + // Nudge the CMS thread to start a concurrent collection. + CMSCollector::request_full_gc(_full_gc_count_before, _gc_cause); + } else { + assert(_full_gc_count_before < gch->total_full_collections(), "Error"); + FullGCCount_lock->notify_all(); // Inform the Java thread its work is done + } +} + +bool VM_GenCollectFullConcurrent::evaluate_at_safepoint() const { + Thread* thr = Thread::current(); + assert(thr != NULL, "Unexpected tid"); + if (!thr->is_Java_thread()) { + assert(thr->is_VM_thread(), "Expected to be evaluated by VM thread"); + GenCollectedHeap* gch = GenCollectedHeap::heap(); + if (_gc_count_before != gch->total_collections()) { + // No need to do a young gc, we'll just nudge the CMS thread + // in the doit() method above, to be executed soon. + assert(_gc_count_before < gch->total_collections(), + "total_collections() should be monotonically increasing"); + return false; // no need for foreground young gc + } + } + return true; // may still need foreground young gc +} + + +void VM_GenCollectFullConcurrent::doit_epilogue() { + Thread* thr = Thread::current(); + assert(thr->is_Java_thread(), "just checking"); + JavaThread* jt = (JavaThread*)thr; + // Release the Heap_lock first. + Heap_lock->unlock(); + release_and_notify_pending_list_lock(); + + // It is fine to test whether completed collections has + // exceeded our request count without locking because + // the completion count is monotonically increasing; + // this will break for very long-running apps when the + // count overflows and wraps around. XXX fix me !!! + // e.g. at the rate of 1 full gc per ms, this could + // overflow in about 1000 years. + GenCollectedHeap* gch = GenCollectedHeap::heap(); + if (_gc_cause != GCCause::_gc_locker && + gch->total_full_collections_completed() <= _full_gc_count_before) { + // maybe we should change the condition to test _gc_cause == + // GCCause::_java_lang_system_gc, instead of + // _gc_cause != GCCause::_gc_locker + assert(_gc_cause == GCCause::_java_lang_system_gc, + "the only way to get here if this was a System.gc()-induced GC"); + assert(ExplicitGCInvokesConcurrent, "Error"); + // Now, wait for witnessing concurrent gc cycle to complete, + // but do so in native mode, because we want to lock the + // FullGCEvent_lock, which may be needed by the VM thread + // or by the CMS thread, so we do not want to be suspended + // while holding that lock. + ThreadToNativeFromVM native(jt); + MutexLockerEx ml(FullGCCount_lock, Mutex::_no_safepoint_check_flag); + // Either a concurrent or a stop-world full gc is sufficient + // witness to our request. + while (gch->total_full_collections_completed() <= _full_gc_count_before) { + FullGCCount_lock->wait(Mutex::_no_safepoint_check_flag); + } + } +}