| /* |
| * Copyright (c) 2001, 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/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); |
| _gc_succeeded = g1h->do_full_collection(true /* explicit_gc */, 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), |
| _gc_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. |
| _gc_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->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. |
| _gc_succeeded = g1h->do_collection_pause_at_safepoint(_target_pause_time_ms); |
| |
| if (_gc_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, &_gc_succeeded); |
| } else { |
| bool should_upgrade_to_full = g1h->should_upgrade_to_full_gc(_gc_cause); |
| |
| 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"); |
| _gc_succeeded = g1h->do_full_collection(false, /* explicit gc */ |
| true /* clear_all_soft_refs */); |
| } |
| } |
| guarantee(_gc_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(); |
| } |
