1 /*
2 * Copyright (c) 2001, 2015, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "gc_implementation/g1/concurrentMarkThread.inline.hpp"
27 #include "gc_implementation/g1/g1CollectedHeap.inline.hpp"
28 #include "gc_implementation/g1/g1CollectorPolicy.hpp"
29 #include "gc_implementation/g1/g1Log.hpp"
30 #include "gc_implementation/g1/vm_operations_g1.hpp"
31 #include "gc_implementation/shared/gcTimer.hpp"
32 #include "gc_implementation/shared/gcTraceTime.hpp"
33 #include "gc_implementation/shared/isGCActiveMark.hpp"
34 #include "gc_implementation/g1/vm_operations_g1.hpp"
35 #include "runtime/interfaceSupport.hpp"
36
37 VM_G1CollectForAllocation::VM_G1CollectForAllocation(uint gc_count_before,
38 size_t word_size,
39 uint gc_attempt)
40 : VM_G1OperationWithAllocRequest(gc_count_before, word_size,
41 GCCause::_allocation_failure,
42 gc_attempt) {
43 guarantee(word_size != 0, "An allocation should always be requested with this operation.");
44 }
45
46 void VM_G1CollectForAllocation::doit() {
47 G1CollectedHeap* g1h = G1CollectedHeap::heap();
48 GCCauseSetter x(g1h, _gc_cause);
49
50 _result = g1h->satisfy_failed_allocation(_word_size, allocation_context(), &_pause_succeeded);
51 assert(_result == NULL || _pause_succeeded,
52 "if we get back a result, the pause should have succeeded");
53 }
54
55 void VM_G1CollectFull::doit() {
56 G1CollectedHeap* g1h = G1CollectedHeap::heap();
57 GCCauseSetter x(g1h, _gc_cause);
58 g1h->do_full_collection(false /* clear_all_soft_refs */);
59 }
60
61 VM_G1IncCollectionPause::VM_G1IncCollectionPause(uint gc_count_before,
62 size_t word_size,
63 bool should_initiate_conc_mark,
64 double target_pause_time_ms,
65 GCCause::Cause gc_cause,
66 uint gc_attempt)
67 : VM_G1OperationWithAllocRequest(gc_count_before, word_size, gc_cause, gc_attempt),
68 _should_initiate_conc_mark(should_initiate_conc_mark),
69 _target_pause_time_ms(target_pause_time_ms),
70 _should_retry_gc(false),
71 _old_marking_cycles_completed_before(0) {
72 guarantee(target_pause_time_ms > 0.0,
73 err_msg("target_pause_time_ms = %1.6lf should be positive",
74 target_pause_time_ms));
75 _gc_cause = gc_cause;
76 }
77
78 bool VM_G1IncCollectionPause::doit_prologue() {
79 bool res = VM_G1OperationWithAllocRequest::doit_prologue();
80 if (!res) {
81 if (_should_initiate_conc_mark) {
82 // The prologue can fail for a couple of reasons. The first is that another GC
83 // got scheduled and prevented the scheduling of the initial mark GC. The
84 // second is that the GC locker may be active and the heap can't be expanded.
85 // In both cases we want to retry the GC so that the initial mark pause is
86 // actually scheduled. In the second case, however, we should stall until
87 // until the GC locker is no longer active and then retry the initial mark GC.
88 _should_retry_gc = true;
89 }
90 }
91 return res;
92 }
93
94 void VM_G1IncCollectionPause::doit() {
95 G1CollectedHeap* g1h = G1CollectedHeap::heap();
96 assert(!_should_initiate_conc_mark || g1h->should_do_concurrent_full_gc(_gc_cause),
97 "only a GC locker, a System.gc(), stats update, whitebox, or a hum allocation induced GC should start a cycle");
98
99 if (_word_size > 0) {
100 // An allocation has been requested. So, try to do that first.
101 _result = g1h->attempt_allocation_at_safepoint(_word_size, allocation_context(),
102 false /* expect_null_cur_alloc_region */);
103 if (_result != NULL) {
104 // If we can successfully allocate before we actually do the
105 // pause then we will consider this pause successful.
106 _pause_succeeded = true;
107 return;
108 }
109 }
110
111 GCCauseSetter x(g1h, _gc_cause);
112 if (_should_initiate_conc_mark) {
113 // It's safer to read old_marking_cycles_completed() here, given
114 // that noone else will be updating it concurrently. Since we'll
115 // only need it if we're initiating a marking cycle, no point in
116 // setting it earlier.
117 _old_marking_cycles_completed_before = g1h->old_marking_cycles_completed();
118
119 // At this point we are supposed to start a concurrent cycle. We
120 // will do so if one is not already in progress.
121 bool res = g1h->g1_policy()->force_initial_mark_if_outside_cycle(_gc_cause);
122
123 // The above routine returns true if we were able to force the
124 // next GC pause to be an initial mark; it returns false if a
125 // marking cycle is already in progress.
126 //
127 // If a marking cycle is already in progress just return and skip the
128 // pause below - if the reason for requesting this initial mark pause
129 // was due to a System.gc() then the requesting thread should block in
130 // doit_epilogue() until the marking cycle is complete.
131 //
132 // If this initial mark pause was requested as part of a humongous
133 // allocation then we know that the marking cycle must just have
134 // been started by another thread (possibly also allocating a humongous
135 // object) as there was no active marking cycle when the requesting
136 // thread checked before calling collect() in
137 // attempt_allocation_humongous(). Retrying the GC, in this case,
138 // will cause the requesting thread to spin inside collect() until the
139 // just started marking cycle is complete - which may be a while. So
140 // we do NOT retry the GC.
141 if (!res) {
142 assert(_word_size == 0, "Concurrent Full GC/Humongous Object IM shouldn't be allocating");
143 if (_gc_cause != GCCause::_g1_humongous_allocation) {
144 _should_retry_gc = true;
145 }
146 return;
147 }
148 }
149
150 _pause_succeeded =
151 g1h->do_collection_pause_at_safepoint(_target_pause_time_ms);
152 if (_pause_succeeded && _word_size > 0) {
153 // An allocation had been requested.
154 _result = g1h->attempt_allocation_at_safepoint(_word_size, allocation_context(),
155 true /* expect_null_cur_alloc_region */);
156 } else {
157 assert(_result == NULL, "invariant");
158 if (!_pause_succeeded) {
159 // Another possible reason reason for the pause to not be successful
160 // is that, again, the GC locker is active (and has become active
161 // since the prologue was executed). In this case we should retry
162 // the pause after waiting for the GC locker to become inactive.
163 _should_retry_gc = true;
164 }
165 }
166 }
167
168 void VM_G1IncCollectionPause::doit_epilogue() {
169 VM_G1OperationWithAllocRequest::doit_epilogue();
170
171 // If the pause was initiated by a System.gc() and
172 // +ExplicitGCInvokesConcurrent, we have to wait here for the cycle
173 // that just started (or maybe one that was already in progress) to
174 // finish.
175 if (_gc_cause == GCCause::_java_lang_system_gc &&
176 _should_initiate_conc_mark) {
177 assert(ExplicitGCInvokesConcurrent,
178 "the only way to be here is if ExplicitGCInvokesConcurrent is set");
179
180 G1CollectedHeap* g1h = G1CollectedHeap::heap();
181
182 // In the doit() method we saved g1h->old_marking_cycles_completed()
183 // in the _old_marking_cycles_completed_before field. We have to
184 // wait until we observe that g1h->old_marking_cycles_completed()
185 // has increased by at least one. This can happen if a) we started
186 // a cycle and it completes, b) a cycle already in progress
187 // completes, or c) a Full GC happens.
188
189 // If the condition has already been reached, there's no point in
190 // actually taking the lock and doing the wait.
191 if (g1h->old_marking_cycles_completed() <=
192 _old_marking_cycles_completed_before) {
193 // The following is largely copied from CMS
194
195 Thread* thr = Thread::current();
196 assert(thr->is_Java_thread(), "invariant");
197 JavaThread* jt = (JavaThread*)thr;
198 ThreadToNativeFromVM native(jt);
199
200 MutexLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
201 while (g1h->old_marking_cycles_completed() <=
202 _old_marking_cycles_completed_before) {
203 FullGCCount_lock->wait(Mutex::_no_safepoint_check_flag);
204 }
205 }
206 }
207 }
208
209 void VM_CGC_Operation::acquire_pending_list_lock() {
210 assert(_needs_pll, "don't call this otherwise");
211 // The caller may block while communicating
212 // with the SLT thread in order to acquire/release the PLL.
213 SurrogateLockerThread* slt = ConcurrentMarkThread::slt();
214 if (slt != NULL) {
215 slt->manipulatePLL(SurrogateLockerThread::acquirePLL);
216 } else {
217 SurrogateLockerThread::report_missing_slt();
218 }
219 }
220
221 void VM_CGC_Operation::release_and_notify_pending_list_lock() {
222 assert(_needs_pll, "don't call this otherwise");
223 // The caller may block while communicating
224 // with the SLT thread in order to acquire/release the PLL.
225 ConcurrentMarkThread::slt()->
226 manipulatePLL(SurrogateLockerThread::releaseAndNotifyPLL);
227 }
228
229 void VM_CGC_Operation::doit() {
230 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
231 GCTraceTime t(_printGCMessage, G1Log::fine(), true, G1CollectedHeap::heap()->gc_timer_cm(), G1CollectedHeap::heap()->concurrent_mark()->concurrent_gc_id());
232 SharedHeap* sh = SharedHeap::heap();
233 // This could go away if CollectedHeap gave access to _gc_is_active...
234 if (sh != NULL) {
235 IsGCActiveMark x;
236 _cl->do_void();
237 } else {
238 _cl->do_void();
239 }
240 }
241
242 bool VM_CGC_Operation::doit_prologue() {
243 // Note the relative order of the locks must match that in
244 // VM_GC_Operation::doit_prologue() or deadlocks can occur
245 if (_needs_pll) {
246 acquire_pending_list_lock();
247 }
248
249 Heap_lock->lock();
250 SharedHeap::heap()->_thread_holds_heap_lock_for_gc = true;
251 return true;
252 }
253
254 void VM_CGC_Operation::doit_epilogue() {
255 // Note the relative order of the unlocks must match that in
256 // VM_GC_Operation::doit_epilogue()
257 SharedHeap::heap()->_thread_holds_heap_lock_for_gc = false;
258 Heap_lock->unlock();
259 if (_needs_pll) {
260 release_and_notify_pending_list_lock();
261 }
262 }