--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/src/hotspot/share/gc/g1/g1VMOperations.cpp Thu Dec 06 15:44:13 2018 +0100
@@ -0,0 +1,224 @@
+/*
+ * Copyright (c) 2001, 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/g1/g1CollectedHeap.inline.hpp"
+#include "gc/g1/g1ConcurrentMarkThread.inline.hpp"
+#include "gc/g1/g1Policy.hpp"
+#include "gc/g1/g1VMOperations.hpp"
+#include "gc/shared/gcId.hpp"
+#include "gc/shared/gcTimer.hpp"
+#include "gc/shared/gcTraceTime.inline.hpp"
+#include "gc/shared/isGCActiveMark.hpp"
+#include "runtime/interfaceSupport.inline.hpp"
+
+void VM_G1CollectFull::doit() {
+ G1CollectedHeap* g1h = G1CollectedHeap::heap();
+ GCCauseSetter x(g1h, _gc_cause);
+ g1h->do_full_collection(false /* clear_all_soft_refs */);
+}
+
+VM_G1CollectForAllocation::VM_G1CollectForAllocation(size_t word_size,
+ uint gc_count_before,
+ GCCause::Cause gc_cause,
+ bool should_initiate_conc_mark,
+ double target_pause_time_ms) :
+ VM_CollectForAllocation(word_size, gc_count_before, gc_cause),
+ _pause_succeeded(false),
+ _should_initiate_conc_mark(should_initiate_conc_mark),
+ _should_retry_gc(false),
+ _target_pause_time_ms(target_pause_time_ms),
+ _old_marking_cycles_completed_before(0) {
+
+ guarantee(target_pause_time_ms > 0.0,
+ "target_pause_time_ms = %1.6lf should be positive",
+ target_pause_time_ms);
+ _gc_cause = gc_cause;
+}
+
+bool VM_G1CollectForAllocation::doit_prologue() {
+ bool res = VM_CollectForAllocation::doit_prologue();
+ if (!res) {
+ if (_should_initiate_conc_mark) {
+ // The prologue can fail for a couple of reasons. The first is that another GC
+ // got scheduled and prevented the scheduling of the initial mark GC. The
+ // second is that the GC locker may be active and the heap can't be expanded.
+ // In both cases we want to retry the GC so that the initial mark pause is
+ // actually scheduled. In the second case, however, we should stall until
+ // until the GC locker is no longer active and then retry the initial mark GC.
+ _should_retry_gc = true;
+ }
+ }
+ return res;
+}
+
+void VM_G1CollectForAllocation::doit() {
+ G1CollectedHeap* g1h = G1CollectedHeap::heap();
+ assert(!_should_initiate_conc_mark || g1h->should_do_concurrent_full_gc(_gc_cause),
+ "only a GC locker, a System.gc(), stats update, whitebox, or a hum allocation induced GC should start a cycle");
+
+ if (_word_size > 0) {
+ // An allocation has been requested. So, try to do that first.
+ _result = g1h->attempt_allocation_at_safepoint(_word_size,
+ false /* expect_null_cur_alloc_region */);
+ if (_result != NULL) {
+ // If we can successfully allocate before we actually do the
+ // pause then we will consider this pause successful.
+ _pause_succeeded = true;
+ return;
+ }
+ }
+
+ GCCauseSetter x(g1h, _gc_cause);
+ if (_should_initiate_conc_mark) {
+ // 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.
+ _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.
+ bool res = g1h->g1_policy()->force_initial_mark_if_outside_cycle(_gc_cause);
+
+ // The above routine returns true if we were able to force the
+ // next GC pause to be an initial mark; it returns false if a
+ // marking cycle is already in progress.
+ //
+ // If a marking cycle is already in progress just return and skip the
+ // pause below - if the reason for requesting this initial mark pause
+ // was due to a System.gc() then the requesting thread should block in
+ // doit_epilogue() until the marking cycle is complete.
+ //
+ // If this initial mark pause was requested as part of a humongous
+ // allocation then we know that the marking cycle must just have
+ // been started by another thread (possibly also allocating a humongous
+ // object) as there was no active marking cycle when the requesting
+ // thread checked before calling collect() in
+ // attempt_allocation_humongous(). Retrying the GC, in this case,
+ // will cause the requesting thread to spin inside collect() until the
+ // just started marking cycle is complete - which may be a while. So
+ // we do NOT retry the GC.
+ if (!res) {
+ assert(_word_size == 0, "Concurrent Full GC/Humongous Object IM shouldn't be allocating");
+ if (_gc_cause != GCCause::_g1_humongous_allocation) {
+ _should_retry_gc = true;
+ }
+ return;
+ }
+ }
+
+ // Try a partial collection of some kind.
+ _pause_succeeded = g1h->do_collection_pause_at_safepoint(_target_pause_time_ms);
+
+ if (_pause_succeeded) {
+ if (_word_size > 0) {
+ // An allocation had been requested. Do it, eventually trying a stronger
+ // kind of GC.
+ _result = g1h->satisfy_failed_allocation(_word_size, &_pause_succeeded);
+ } else {
+ bool should_upgrade_to_full = !g1h->should_do_concurrent_full_gc(_gc_cause) &&
+ !g1h->has_regions_left_for_allocation();
+ if (should_upgrade_to_full) {
+ // There has been a request to perform a GC to free some space. We have no
+ // information on how much memory has been asked for. In case there are
+ // absolutely no regions left to allocate into, do a maximally compacting full GC.
+ log_info(gc, ergo)("Attempting maximally compacting collection");
+ _pause_succeeded = g1h->do_full_collection(false, /* explicit gc */
+ true /* clear_all_soft_refs */);
+ }
+ }
+ guarantee(_pause_succeeded, "Elevated collections during the safepoint must always succeed.");
+ } else {
+ assert(_result == NULL, "invariant");
+ // The only reason for the pause to not be successful is that, the GC locker is
+ // active (or has become active since the prologue was executed). In this case
+ // we should retry the pause after waiting for the GC locker to become inactive.
+ _should_retry_gc = true;
+ }
+}
+
+void VM_G1CollectForAllocation::doit_epilogue() {
+ VM_CollectForAllocation::doit_epilogue();
+
+ // If the pause was initiated by a System.gc() and
+ // +ExplicitGCInvokesConcurrent, we have to wait here for the cycle
+ // that just started (or maybe one that was already in progress) to
+ // finish.
+ if (GCCause::is_user_requested_gc(_gc_cause) &&
+ _should_initiate_conc_mark) {
+ assert(ExplicitGCInvokesConcurrent,
+ "the only way to be here is if ExplicitGCInvokesConcurrent is set");
+
+ G1CollectedHeap* g1h = G1CollectedHeap::heap();
+
+ // 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->old_marking_cycles_completed() <=
+ _old_marking_cycles_completed_before) {
+ // The following is largely copied from CMS
+
+ Thread* thr = Thread::current();
+ assert(thr->is_Java_thread(), "invariant");
+ JavaThread* jt = (JavaThread*)thr;
+ ThreadToNativeFromVM native(jt);
+
+ MutexLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
+ while (g1h->old_marking_cycles_completed() <=
+ _old_marking_cycles_completed_before) {
+ FullGCCount_lock->wait(Mutex::_no_safepoint_check_flag);
+ }
+ }
+ }
+}
+
+void VM_G1Concurrent::doit() {
+ GCIdMark gc_id_mark(_gc_id);
+ GCTraceCPUTime tcpu;
+ G1CollectedHeap* g1h = G1CollectedHeap::heap();
+ GCTraceTime(Info, gc) t(_message, g1h->concurrent_mark()->gc_timer_cm(), GCCause::_no_gc, true);
+ TraceCollectorStats tcs(g1h->g1mm()->conc_collection_counters());
+ SvcGCMarker sgcm(SvcGCMarker::CONCURRENT);
+ IsGCActiveMark x;
+ _cl->do_void();
+}
+
+bool VM_G1Concurrent::doit_prologue() {
+ Heap_lock->lock();
+ return true;
+}
+
+void VM_G1Concurrent::doit_epilogue() {
+ if (Universe::has_reference_pending_list()) {
+ Heap_lock->notify_all();
+ }
+ Heap_lock->unlock();
+}