1 /*
2 * Copyright (c) 2001, 2013, 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(
38 unsigned int gc_count_before,
39 size_t word_size)
40 : VM_G1OperationWithAllocRequest(gc_count_before, word_size,
41 GCCause::_allocation_failure) {
42 guarantee(word_size > 0, "an allocation should always be requested");
43 }
44
45 void VM_G1CollectForAllocation::doit() {
46 G1CollectedHeap* g1h = G1CollectedHeap::heap();
47 GCCauseSetter x(g1h, _gc_cause);
48
49 _result = g1h->satisfy_failed_allocation(_word_size, allocation_context(), &_pause_succeeded);
50 assert(_result == NULL || _pause_succeeded,
51 "if we get back a result, the pause should have succeeded");
52 }
53
54 void VM_G1CollectFull::doit() {
55 G1CollectedHeap* g1h = G1CollectedHeap::heap();
56 GCCauseSetter x(g1h, _gc_cause);
57 g1h->do_full_collection(false /* clear_all_soft_refs */);
58 }
59
60 VM_G1IncCollectionPause::VM_G1IncCollectionPause(
61 unsigned int 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 : VM_G1OperationWithAllocRequest(gc_count_before, word_size, gc_cause),
67 _should_initiate_conc_mark(should_initiate_conc_mark),
68 _target_pause_time_ms(target_pause_time_ms),
69 _should_retry_gc(false),
70 _old_marking_cycles_completed_before(0) {
71 guarantee(target_pause_time_ms > 0.0,
72 err_msg("target_pause_time_ms = %1.6lf should be positive",
73 target_pause_time_ms));
74 _gc_cause = gc_cause;
75 }
76
77 bool VM_G1IncCollectionPause::doit_prologue() {
78 bool res = VM_GC_Operation::doit_prologue();
79 if (!res) {
80 if (_should_initiate_conc_mark) {
81 // The prologue can fail for a couple of reasons. The first is that another GC
82 // got scheduled and prevented the scheduling of the initial mark GC. The
83 // second is that the GC locker may be active and the heap can't be expanded.
84 // In both cases we want to retry the GC so that the initial mark pause is
85 // actually scheduled. In the second case, however, we should stall until
86 // until the GC locker is no longer active and then retry the initial mark GC.
87 _should_retry_gc = true;
88 }
89 }
90 return res;
91 }
92
93 void VM_G1IncCollectionPause::doit() {
94 G1CollectedHeap* g1h = G1CollectedHeap::heap();
95 assert(!_should_initiate_conc_mark || g1h->should_do_concurrent_full_gc(_gc_cause),
96 "only a GC locker, a System.gc(), stats update, whitebox, or a hum allocation induced GC should start a cycle");
97
98 if (_word_size > 0) {
99 // An allocation has been requested. So, try to do that first.
100 _result = g1h->attempt_allocation_at_safepoint(_word_size, allocation_context(),
101 false /* expect_null_cur_alloc_region */);
102 if (_result != NULL) {
103 // If we can successfully allocate before we actually do the
104 // pause then we will consider this pause successful.
105 _pause_succeeded = true;
106 return;
107 }
108 }
109
110 GCCauseSetter x(g1h, _gc_cause);
111 if (_should_initiate_conc_mark) {
112 // It's safer to read old_marking_cycles_completed() here, given
113 // that noone else will be updating it concurrently. Since we'll
114 // only need it if we're initiating a marking cycle, no point in
115 // setting it earlier.
116 _old_marking_cycles_completed_before = g1h->old_marking_cycles_completed();
117
118 // At this point we are supposed to start a concurrent cycle. We
119 // will do so if one is not already in progress.
120 bool res = g1h->g1_policy()->force_initial_mark_if_outside_cycle(_gc_cause);
121
122 // The above routine returns true if we were able to force the
123 // next GC pause to be an initial mark; it returns false if a
124 // marking cycle is already in progress.
125 //
126 // If a marking cycle is already in progress just return and skip the
127 // pause below - if the reason for requesting this initial mark pause
128 // was due to a System.gc() then the requesting thread should block in
129 // doit_epilogue() until the marking cycle is complete.
130 //
131 // If this initial mark pause was requested as part of a humongous
132 // allocation then we know that the marking cycle must just have
133 // been started by another thread (possibly also allocating a humongous
134 // object) as there was no active marking cycle when the requesting
135 // thread checked before calling collect() in
136 // attempt_allocation_humongous(). Retrying the GC, in this case,
137 // will cause the requesting thread to spin inside collect() until the
138 // just started marking cycle is complete - which may be a while. So
139 // we do NOT retry the GC.
140 if (!res) {
141 assert(_word_size == 0, "Concurrent Full GC/Humongous Object IM shouldn't be allocating");
142 if (_gc_cause != GCCause::_g1_humongous_allocation) {
143 _should_retry_gc = true;
144 }
145 return;
146 }
147 }
148
149 _pause_succeeded =
150 g1h->do_collection_pause_at_safepoint(_target_pause_time_ms);
151 if (_pause_succeeded && _word_size > 0) {
152 // An allocation had been requested.
153 _result = g1h->attempt_allocation_at_safepoint(_word_size, allocation_context(),
154 true /* expect_null_cur_alloc_region */);
155 } else {
156 assert(_result == NULL, "invariant");
157 if (!_pause_succeeded) {
158 // Another possible reason reason for the pause to not be successful
159 // is that, again, the GC locker is active (and has become active
160 // since the prologue was executed). In this case we should retry
161 // the pause after waiting for the GC locker to become inactive.
162 _should_retry_gc = true;
163 }
164 }
165 }
166
167 void VM_G1IncCollectionPause::doit_epilogue() {
168 VM_GC_Operation::doit_epilogue();
169
170 // If the pause was initiated by a System.gc() and
171 // +ExplicitGCInvokesConcurrent, we have to wait here for the cycle
172 // that just started (or maybe one that was already in progress) to
173 // finish.
174 if (_gc_cause == GCCause::_java_lang_system_gc &&
175 _should_initiate_conc_mark) {
176 assert(ExplicitGCInvokesConcurrent,
177 "the only way to be here is if ExplicitGCInvokesConcurrent is set");
178
179 G1CollectedHeap* g1h = G1CollectedHeap::heap();
180
181 // In the doit() method we saved g1h->old_marking_cycles_completed()
182 // in the _old_marking_cycles_completed_before field. We have to
183 // wait until we observe that g1h->old_marking_cycles_completed()
184 // has increased by at least one. This can happen if a) we started
185 // a cycle and it completes, b) a cycle already in progress
186 // completes, or c) a Full GC happens.
187
188 // If the condition has already been reached, there's no point in
189 // actually taking the lock and doing the wait.
190 if (g1h->old_marking_cycles_completed() <=
191 _old_marking_cycles_completed_before) {
192 // The following is largely copied from CMS
193
194 Thread* thr = Thread::current();
195 assert(thr->is_Java_thread(), "invariant");
196 JavaThread* jt = (JavaThread*)thr;
197 ThreadToNativeFromVM native(jt);
198
199 MutexLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
200 while (g1h->old_marking_cycles_completed() <=
201 _old_marking_cycles_completed_before) {
202 FullGCCount_lock->wait(Mutex::_no_safepoint_check_flag);
203 }
204 }
205 }
206 }
207
208 void VM_CGC_Operation::acquire_pending_list_lock() {
209 assert(_needs_pll, "don't call this otherwise");
210 // The caller may block while communicating
211 // with the SLT thread in order to acquire/release the PLL.
212 SurrogateLockerThread* slt = ConcurrentMarkThread::slt();
213 if (slt != NULL) {
214 slt->manipulatePLL(SurrogateLockerThread::acquirePLL);
215 } else {
216 SurrogateLockerThread::report_missing_slt();
217 }
218 }
219
220 void VM_CGC_Operation::release_and_notify_pending_list_lock() {
221 assert(_needs_pll, "don't call this otherwise");
222 // The caller may block while communicating
223 // with the SLT thread in order to acquire/release the PLL.
224 ConcurrentMarkThread::slt()->
225 manipulatePLL(SurrogateLockerThread::releaseAndNotifyPLL);
226 }
227
228 void VM_CGC_Operation::doit() {
229 TraceCPUTime tcpu(G1Log::finer(), true, gclog_or_tty);
230 GCTraceTime t(_printGCMessage, G1Log::fine(), true, G1CollectedHeap::heap()->gc_timer_cm(), G1CollectedHeap::heap()->concurrent_mark()->concurrent_gc_id());
231 SharedHeap* sh = SharedHeap::heap();
232 // This could go away if CollectedHeap gave access to _gc_is_active...
233 if (sh != NULL) {
234 IsGCActiveMark x;
235 _cl->do_void();
236 } else {
237 _cl->do_void();
238 }
239 }
240
241 bool VM_CGC_Operation::doit_prologue() {
242 // Note the relative order of the locks must match that in
243 // VM_GC_Operation::doit_prologue() or deadlocks can occur
244 if (_needs_pll) {
245 acquire_pending_list_lock();
246 }
247
248 Heap_lock->lock();
249 SharedHeap::heap()->_thread_holds_heap_lock_for_gc = true;
250 return true;
251 }
252
253 void VM_CGC_Operation::doit_epilogue() {
254 // Note the relative order of the unlocks must match that in
255 // VM_GC_Operation::doit_epilogue()
256 SharedHeap::heap()->_thread_holds_heap_lock_for_gc = false;
257 Heap_lock->unlock();
258 if (_needs_pll) {
259 release_and_notify_pending_list_lock();
260 }
261 }