--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/src/hotspot/share/gc/cms/cmsVMOperations.cpp Thu Dec 06 15:44:13 2018 +0100
@@ -0,0 +1,254 @@
+/*
+ * Copyright (c) 2005, 2018, 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 "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);
+ MutexLockerEx 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);
+ 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");
+
+ 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");
+
+ MutexLockerEx 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);
+ 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 (heap->total_full_collections_completed() <= _full_gc_count_before) {
+ FullGCCount_lock->wait(Mutex::_no_safepoint_check_flag);
+ }
+ }
+}