| /* |
| * Copyright (c) 2005, 2016, 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.inline.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::verify_before_gc() { |
| if (VerifyBeforeGC && |
| GenCollectedHeap::heap()->total_collections() >= VerifyGCStartAt) { |
| GCTraceTime(Info, gc, phases, verify) tm("Verify Before", _collector->_gc_timer_cm); |
| 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(Info, gc, phases, verify) tm("Verify After", _collector->_gc_timer_cm); |
| 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"); |
| |
| 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"); |
| |
| 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(); |
| GCIdMark gc_id_mark(_gc_id); |
| |
| _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(), GenCollectedHeap::YoungGen); |
| } // Else no need for a foreground young gc |
| assert((_gc_count_before < gch->total_collections()) || |
| (GCLocker::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; |
| |
| 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. |
| 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 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); |
| 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); |
| } |
| } |
| } |