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 : VM_G1OperationWithAllocRequest(gc_count_before, word_size,
40 GCCause::_allocation_failure) {
41 guarantee(word_size > 0, "an allocation should always be requested");
42 }
43
44 void VM_G1CollectForAllocation::doit() {
45 G1CollectedHeap* g1h = G1CollectedHeap::heap();
46 GCCauseSetter x(g1h, _gc_cause);
47
48 _result = g1h->satisfy_failed_allocation(_word_size, allocation_context(), &_pause_succeeded);
49 assert(_result == NULL || _pause_succeeded,
50 "if we get back a result, the pause should have succeeded");
51 }
52
53 void VM_G1CollectFull::doit() {
54 G1CollectedHeap* g1h = G1CollectedHeap::heap();
55 GCCauseSetter x(g1h, _gc_cause);
56 g1h->do_full_collection(false /* clear_all_soft_refs */);
57 }
58
59 VM_G1IncCollectionPause::VM_G1IncCollectionPause(uint gc_count_before,
60 size_t word_size,
61 bool should_initiate_conc_mark,
62 double target_pause_time_ms,
63 GCCause::Cause gc_cause)
64 : VM_G1OperationWithAllocRequest(gc_count_before, word_size, gc_cause),
65 _should_initiate_conc_mark(should_initiate_conc_mark),
66 _target_pause_time_ms(target_pause_time_ms),
67 _should_retry_gc(false),
68 _old_marking_cycles_completed_before(0) {
69 guarantee(target_pause_time_ms > 0.0,
70 err_msg("target_pause_time_ms = %1.6lf should be positive",
71 target_pause_time_ms));
72 _gc_cause = gc_cause;
73 }
74
75 bool VM_G1IncCollectionPause::doit_prologue() {
76 bool res = VM_GC_Operation::doit_prologue();
77 if (!res) {
78 if (_should_initiate_conc_mark) {
79 // The prologue can fail for a couple of reasons. The first is that another GC
80 // got scheduled and prevented the scheduling of the initial mark GC. The
81 // second is that the GC locker may be active and the heap can't be expanded.
82 // In both cases we want to retry the GC so that the initial mark pause is
83 // actually scheduled. In the second case, however, we should stall until
84 // until the GC locker is no longer active and then retry the initial mark GC.
85 _should_retry_gc = true;
86 }
87 }
88 return res;
89 }
90
91 void VM_G1IncCollectionPause::doit() {
92 G1CollectedHeap* g1h = G1CollectedHeap::heap();
93 assert(!_should_initiate_conc_mark || g1h->should_do_concurrent_full_gc(_gc_cause),
94 "only a GC locker, a System.gc(), stats update, whitebox, or a hum allocation induced GC should start a cycle");
95
96 if (_word_size > 0) {
97 // An allocation has been requested. So, try to do that first.
98 _result = g1h->attempt_allocation_at_safepoint(_word_size, allocation_context(),
99 false /* expect_null_cur_alloc_region */);
100 if (_result != NULL) {
101 // If we can successfully allocate before we actually do the
102 // pause then we will consider this pause successful.
103 _pause_succeeded = true;
104 return;
105 }
106 }
107
108 GCCauseSetter x(g1h, _gc_cause);
109 if (_should_initiate_conc_mark) {
110 // It's safer to read old_marking_cycles_completed() here, given
111 // that noone else will be updating it concurrently. Since we'll
112 // only need it if we're initiating a marking cycle, no point in
113 // setting it earlier.
114 _old_marking_cycles_completed_before = g1h->old_marking_cycles_completed();
115
116 // At this point we are supposed to start a concurrent cycle. We
117 // will do so if one is not already in progress.
118 bool res = g1h->g1_policy()->force_initial_mark_if_outside_cycle(_gc_cause);
119
120 // The above routine returns true if we were able to force the
121 // next GC pause to be an initial mark; it returns false if a
122 // marking cycle is already in progress.
123 //
124 // If a marking cycle is already in progress just return and skip the
125 // pause below - if the reason for requesting this initial mark pause
126 // was due to a System.gc() then the requesting thread should block in
127 // doit_epilogue() until the marking cycle is complete.
128 //
129 // If this initial mark pause was requested as part of a humongous
130 // allocation then we know that the marking cycle must just have
131 // been started by another thread (possibly also allocating a humongous
132 // object) as there was no active marking cycle when the requesting
133 // thread checked before calling collect() in
134 // attempt_allocation_humongous(). Retrying the GC, in this case,
135 // will cause the requesting thread to spin inside collect() until the
136 // just started marking cycle is complete - which may be a while. So
137 // we do NOT retry the GC.
138 if (!res) {
139 assert(_word_size == 0, "Concurrent Full GC/Humongous Object IM shouldn't be allocating");
140 if (_gc_cause != GCCause::_g1_humongous_allocation) {
141 _should_retry_gc = true;
142 }
143 return;
144 }
145 }
146
147 _pause_succeeded =
148 g1h->do_collection_pause_at_safepoint(_target_pause_time_ms);
149 if (_pause_succeeded && _word_size > 0) {
150 // An allocation had been requested.
151 _result = g1h->attempt_allocation_at_safepoint(_word_size, allocation_context(),
152 true /* expect_null_cur_alloc_region */);
153 } else {
154 assert(_result == NULL, "invariant");
155 if (!_pause_succeeded) {
156 // Another possible reason reason for the pause to not be successful
157 // is that, again, the GC locker is active (and has become active
158 // since the prologue was executed). In this case we should retry
159 // the pause after waiting for the GC locker to become inactive.
160 _should_retry_gc = true;
161 }
162 }
163 }
164
165 void VM_G1IncCollectionPause::doit_epilogue() {
166 VM_GC_Operation::doit_epilogue();
167
168 // If the pause was initiated by a System.gc() and
169 // +ExplicitGCInvokesConcurrent, we have to wait here for the cycle
170 // that just started (or maybe one that was already in progress) to
171 // finish.
172 if (_gc_cause == GCCause::_java_lang_system_gc &&
173 _should_initiate_conc_mark) {
174 assert(ExplicitGCInvokesConcurrent,
175 "the only way to be here is if ExplicitGCInvokesConcurrent is set");
176
177 G1CollectedHeap* g1h = G1CollectedHeap::heap();
178
179 // In the doit() method we saved g1h->old_marking_cycles_completed()
180 // in the _old_marking_cycles_completed_before field. We have to
181 // wait until we observe that g1h->old_marking_cycles_completed()
182 // has increased by at least one. This can happen if a) we started
183 // a cycle and it completes, b) a cycle already in progress
184 // completes, or c) a Full GC happens.
185
186 // If the condition has already been reached, there's no point in
187 // actually taking the lock and doing the wait.
188 if (g1h->old_marking_cycles_completed() <=
189 _old_marking_cycles_completed_before) {
190 // The following is largely copied from CMS
191
192 Thread* thr = Thread::current();
193 assert(thr->is_Java_thread(), "invariant");
194 JavaThread* jt = (JavaThread*)thr;
195 ThreadToNativeFromVM native(jt);
196
197 MutexLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
198 while (g1h->old_marking_cycles_completed() <=
199 _old_marking_cycles_completed_before) {
200 FullGCCount_lock->wait(Mutex::_no_safepoint_check_flag);
201 }
202 }
203 }
204 }
205
206 void VM_CGC_Operation::acquire_pending_list_lock() {
207 assert(_needs_pll, "don't call this otherwise");
208 // The caller may block while communicating
209 // with the SLT thread in order to acquire/release the PLL.
210 SurrogateLockerThread* slt = ConcurrentMarkThread::slt();
211 if (slt != NULL) {
212 slt->manipulatePLL(SurrogateLockerThread::acquirePLL);
213 } else {
214 SurrogateLockerThread::report_missing_slt();
215 }
216 }
217
218 void VM_CGC_Operation::release_and_notify_pending_list_lock() {
219 assert(_needs_pll, "don't call this otherwise");
220 // The caller may block while communicating
221 // with the SLT thread in order to acquire/release the PLL.
222 ConcurrentMarkThread::slt()->
223 manipulatePLL(SurrogateLockerThread::releaseAndNotifyPLL);
224 }
225
226 void VM_CGC_Operation::doit() {
227 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
228 GCTraceTime t(_printGCMessage, G1Log::fine(), true, G1CollectedHeap::heap()->gc_timer_cm(), G1CollectedHeap::heap()->concurrent_mark()->concurrent_gc_id());
229 SharedHeap* sh = SharedHeap::heap();
230 // This could go away if CollectedHeap gave access to _gc_is_active...
231 if (sh != NULL) {
232 IsGCActiveMark x;
233 _cl->do_void();
234 } else {
235 _cl->do_void();
236 }
237 }
238
239 bool VM_CGC_Operation::doit_prologue() {
240 // Note the relative order of the locks must match that in
241 // VM_GC_Operation::doit_prologue() or deadlocks can occur
242 if (_needs_pll) {
243 acquire_pending_list_lock();
244 }
245
246 Heap_lock->lock();
247 SharedHeap::heap()->_thread_holds_heap_lock_for_gc = true;
248 return true;
249 }
250
251 void VM_CGC_Operation::doit_epilogue() {
252 // Note the relative order of the unlocks must match that in
253 // VM_GC_Operation::doit_epilogue()
254 SharedHeap::heap()->_thread_holds_heap_lock_for_gc = false;
255 Heap_lock->unlock();
256 if (_needs_pll) {
257 release_and_notify_pending_list_lock();
258 }
259 }