diff -r 4e648a2d8480 -r 7893d1012580 src/hotspot/share/gc/cms/cmsVMOperations.cpp --- a/src/hotspot/share/gc/cms/cmsVMOperations.cpp Thu Nov 14 12:38:31 2019 +0000 +++ /dev/null Thu Jan 01 00:00:00 1970 +0000 @@ -1,255 +0,0 @@ -/* - * Copyright (c) 2005, 2019, 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/cmsHeap.hpp" -#include "gc/cms/cmsVMOperations.hpp" -#include "gc/cms/concurrentMarkSweepGeneration.inline.hpp" -#include "gc/cms/concurrentMarkSweepThread.hpp" -#include "gc/shared/gcLocker.hpp" -#include "gc/shared/gcTimer.hpp" -#include "gc/shared/gcTraceTime.inline.hpp" -#include "gc/shared/isGCActiveMark.hpp" -#include "memory/universe.hpp" -#include "runtime/handles.inline.hpp" -#include "runtime/interfaceSupport.inline.hpp" -#include "runtime/os.hpp" -#include "utilities/dtrace.hpp" - -////////////////////////////////////////////////////////// -// Methods in abstract class VM_CMS_Operation -////////////////////////////////////////////////////////// -void VM_CMS_Operation::verify_before_gc() { - if (VerifyBeforeGC && - CMSHeap::heap()->total_collections() >= VerifyGCStartAt) { - GCTraceTime(Info, gc, phases, verify) tm("Verify Before", _collector->_gc_timer_cm); - HandleMark hm; - FreelistLocker x(_collector); - MutexLocker y(_collector->bitMapLock(), Mutex::_no_safepoint_check_flag); - CMSHeap::heap()->prepare_for_verify(); - Universe::verify(); - } -} - -void VM_CMS_Operation::verify_after_gc() { - if (VerifyAfterGC && - CMSHeap::heap()->total_collections() >= VerifyGCStartAt) { - GCTraceTime(Info, gc, phases, verify) tm("Verify After", _collector->_gc_timer_cm); - HandleMark hm; - FreelistLocker x(_collector); - MutexLocker 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"); - - Heap_lock->lock(); - if (lost_race()) { - assert(_prologue_succeeded == false, "Initialized in c'tor"); - Heap_lock->unlock(); - } 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"); - - if (Universe::has_reference_pending_list()) { - Heap_lock->notify_all(); - } - Heap_lock->unlock(); -} - -////////////////////////////////////////////////////////// -// 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(); - GCIdMark gc_id_mark(_gc_id); - - _collector->_gc_timer_cm->register_gc_pause_start("Initial Mark"); - - CMSHeap* heap = CMSHeap::heap(); - GCCauseSetter gccs(heap, GCCause::_cms_initial_mark); - - VM_CMS_Operation::verify_before_gc(); - - IsGCActiveMark x; // stop-world GC active - _collector->do_CMS_operation(CMSCollector::CMS_op_checkpointRootsInitial, heap->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(); - GCIdMark gc_id_mark(_gc_id); - - _collector->_gc_timer_cm->register_gc_pause_start("Final Mark"); - - CMSHeap* heap = CMSHeap::heap(); - GCCauseSetter gccs(heap, GCCause::_cms_final_remark); - - VM_CMS_Operation::verify_before_gc(); - - IsGCActiveMark x; // stop-world GC active - _collector->do_CMS_operation(CMSCollector::CMS_op_checkpointRootsFinal, heap->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"); - - CMSHeap* heap = CMSHeap::heap(); - if (_gc_count_before == heap->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(heap, _gc_cause); - heap->do_full_collection(heap->must_clear_all_soft_refs(), GenCollectedHeap::YoungGen); - } // Else no need for a foreground young gc - assert((_gc_count_before < heap->total_collections()) || - (GCLocker::is_active() /* gc may have been skipped */ - && (_gc_count_before == heap->total_collections())), - "total_collections() should be monotonically increasing"); - - MutexLocker x(FullGCCount_lock, Mutex::_no_safepoint_check_flag); - assert(_full_gc_count_before <= heap->total_full_collections(), "Error"); - if (heap->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 < heap->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"); - CMSHeap* heap = CMSHeap::heap(); - if (_gc_count_before != heap->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 < heap->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; - - if (Universe::has_reference_pending_list()) { - Heap_lock->notify_all(); - } - Heap_lock->unlock(); - - // 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. - CMSHeap* heap = CMSHeap::heap(); - if (_gc_cause != GCCause::_gc_locker && - heap->total_full_collections_completed() <= _full_gc_count_before) { - // maybe we should change the condition to test _gc_cause == - // GCCause::_java_lang_system_gc or GCCause::_dcmd_gc_run, - // instead of _gc_cause != GCCause::_gc_locker - assert(GCCause::is_user_requested_gc(_gc_cause), - "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); - MutexLocker ml(FullGCCount_lock, Mutex::_no_safepoint_check_flag); - // Either a concurrent or a stop-world full gc is sufficient - // witness to our request. - while (heap->total_full_collections_completed() <= _full_gc_count_before) { - FullGCCount_lock->wait_without_safepoint_check(); - } - } -}