Mercurial > hg > truffle
annotate src/share/vm/gc_implementation/concurrentMarkSweep/vmCMSOperations.cpp @ 14662:3c3953fb3f2a
8033380: Experimental VM flag to enforce access atomicity
Summary: -XX:+AlwaysAtomicAccesses to unconditionally enforce the access atomicity.
Reviewed-by: roland, kvn, iveresov
author | shade |
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date | Mon, 03 Mar 2014 15:54:45 +0400 |
parents | e6195383bcaf |
children | 4ca6dc0799b6 |
rev | line source |
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0 | 1 /* |
10405 | 2 * Copyright (c) 2005, 2013, Oracle and/or its affiliates. All rights reserved. |
0 | 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 * | |
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19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
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20 * or visit www.oracle.com if you need additional information or have any |
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21 * questions. |
0 | 22 * |
23 */ | |
24 | |
1972 | 25 #include "precompiled.hpp" |
26 #include "gc_implementation/concurrentMarkSweep/concurrentMarkSweepGeneration.inline.hpp" | |
27 #include "gc_implementation/concurrentMarkSweep/concurrentMarkSweepThread.hpp" | |
28 #include "gc_implementation/concurrentMarkSweep/vmCMSOperations.hpp" | |
10405 | 29 #include "gc_implementation/shared/gcTimer.hpp" |
30 #include "gc_implementation/shared/gcTraceTime.hpp" | |
1972 | 31 #include "gc_implementation/shared/isGCActiveMark.hpp" |
32 #include "memory/gcLocker.inline.hpp" | |
33 #include "runtime/interfaceSupport.hpp" | |
10405 | 34 #include "runtime/os.hpp" |
1972 | 35 #include "utilities/dtrace.hpp" |
4006 | 36 |
37 | |
0 | 38 ////////////////////////////////////////////////////////// |
39 // Methods in abstract class VM_CMS_Operation | |
40 ////////////////////////////////////////////////////////// | |
41 void VM_CMS_Operation::acquire_pending_list_lock() { | |
42 // The caller may block while communicating | |
43 // with the SLT thread in order to acquire/release the PLL. | |
44 ConcurrentMarkSweepThread::slt()-> | |
45 manipulatePLL(SurrogateLockerThread::acquirePLL); | |
46 } | |
47 | |
48 void VM_CMS_Operation::release_and_notify_pending_list_lock() { | |
49 // The caller may block while communicating | |
50 // with the SLT thread in order to acquire/release the PLL. | |
51 ConcurrentMarkSweepThread::slt()-> | |
52 manipulatePLL(SurrogateLockerThread::releaseAndNotifyPLL); | |
53 } | |
54 | |
55 void VM_CMS_Operation::verify_before_gc() { | |
56 if (VerifyBeforeGC && | |
57 GenCollectedHeap::heap()->total_collections() >= VerifyGCStartAt) { | |
10405 | 58 GCTraceTime tm("Verify Before", false, false, _collector->_gc_timer_cm); |
0 | 59 HandleMark hm; |
60 FreelistLocker x(_collector); | |
61 MutexLockerEx y(_collector->bitMapLock(), Mutex::_no_safepoint_check_flag); | |
62 Universe::heap()->prepare_for_verify(); | |
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63 Universe::verify(); |
0 | 64 } |
65 } | |
66 | |
67 void VM_CMS_Operation::verify_after_gc() { | |
68 if (VerifyAfterGC && | |
69 GenCollectedHeap::heap()->total_collections() >= VerifyGCStartAt) { | |
10405 | 70 GCTraceTime tm("Verify After", false, false, _collector->_gc_timer_cm); |
0 | 71 HandleMark hm; |
72 FreelistLocker x(_collector); | |
73 MutexLockerEx y(_collector->bitMapLock(), Mutex::_no_safepoint_check_flag); | |
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74 Universe::verify(); |
0 | 75 } |
76 } | |
77 | |
78 bool VM_CMS_Operation::lost_race() const { | |
79 if (CMSCollector::abstract_state() == CMSCollector::Idling) { | |
80 // We lost a race to a foreground collection | |
81 // -- there's nothing to do | |
82 return true; | |
83 } | |
84 assert(CMSCollector::abstract_state() == legal_state(), | |
85 "Inconsistent collector state?"); | |
86 return false; | |
87 } | |
88 | |
89 bool VM_CMS_Operation::doit_prologue() { | |
90 assert(Thread::current()->is_ConcurrentGC_thread(), "just checking"); | |
91 assert(!CMSCollector::foregroundGCShouldWait(), "Possible deadlock"); | |
92 assert(!ConcurrentMarkSweepThread::cms_thread_has_cms_token(), | |
93 "Possible deadlock"); | |
94 | |
95 if (needs_pll()) { | |
96 acquire_pending_list_lock(); | |
97 } | |
98 // Get the Heap_lock after the pending_list_lock. | |
99 Heap_lock->lock(); | |
100 if (lost_race()) { | |
101 assert(_prologue_succeeded == false, "Initialized in c'tor"); | |
102 Heap_lock->unlock(); | |
103 if (needs_pll()) { | |
104 release_and_notify_pending_list_lock(); | |
105 } | |
106 } else { | |
107 _prologue_succeeded = true; | |
108 } | |
109 return _prologue_succeeded; | |
110 } | |
111 | |
112 void VM_CMS_Operation::doit_epilogue() { | |
113 assert(Thread::current()->is_ConcurrentGC_thread(), "just checking"); | |
114 assert(!CMSCollector::foregroundGCShouldWait(), "Possible deadlock"); | |
115 assert(!ConcurrentMarkSweepThread::cms_thread_has_cms_token(), | |
116 "Possible deadlock"); | |
117 | |
118 // Release the Heap_lock first. | |
119 Heap_lock->unlock(); | |
120 if (needs_pll()) { | |
121 release_and_notify_pending_list_lock(); | |
122 } | |
123 } | |
124 | |
125 ////////////////////////////////////////////////////////// | |
126 // Methods in class VM_CMS_Initial_Mark | |
127 ////////////////////////////////////////////////////////// | |
128 void VM_CMS_Initial_Mark::doit() { | |
129 if (lost_race()) { | |
130 // Nothing to do. | |
131 return; | |
132 } | |
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133 HS_PRIVATE_CMS_INITMARK_BEGIN(); |
0 | 134 |
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135 _collector->_gc_timer_cm->register_gc_pause_start("Initial Mark"); |
10405 | 136 |
0 | 137 GenCollectedHeap* gch = GenCollectedHeap::heap(); |
138 GCCauseSetter gccs(gch, GCCause::_cms_initial_mark); | |
139 | |
140 VM_CMS_Operation::verify_before_gc(); | |
141 | |
142 IsGCActiveMark x; // stop-world GC active | |
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143 _collector->do_CMS_operation(CMSCollector::CMS_op_checkpointRootsInitial, gch->gc_cause()); |
0 | 144 |
145 VM_CMS_Operation::verify_after_gc(); | |
10405 | 146 |
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147 _collector->_gc_timer_cm->register_gc_pause_end(); |
10405 | 148 |
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149 HS_PRIVATE_CMS_INITMARK_END(); |
0 | 150 } |
151 | |
152 ////////////////////////////////////////////////////////// | |
153 // Methods in class VM_CMS_Final_Remark_Operation | |
154 ////////////////////////////////////////////////////////// | |
155 void VM_CMS_Final_Remark::doit() { | |
156 if (lost_race()) { | |
157 // Nothing to do. | |
158 return; | |
159 } | |
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160 HS_PRIVATE_CMS_REMARK_BEGIN(); |
0 | 161 |
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162 _collector->_gc_timer_cm->register_gc_pause_start("Final Mark"); |
10405 | 163 |
0 | 164 GenCollectedHeap* gch = GenCollectedHeap::heap(); |
165 GCCauseSetter gccs(gch, GCCause::_cms_final_remark); | |
166 | |
167 VM_CMS_Operation::verify_before_gc(); | |
168 | |
169 IsGCActiveMark x; // stop-world GC active | |
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170 _collector->do_CMS_operation(CMSCollector::CMS_op_checkpointRootsFinal, gch->gc_cause()); |
0 | 171 |
172 VM_CMS_Operation::verify_after_gc(); | |
10405 | 173 |
174 _collector->save_heap_summary(); | |
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175 _collector->_gc_timer_cm->register_gc_pause_end(); |
10405 | 176 |
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177 HS_PRIVATE_CMS_REMARK_END(); |
0 | 178 } |
179 | |
180 // VM operation to invoke a concurrent collection of a | |
181 // GenCollectedHeap heap. | |
182 void VM_GenCollectFullConcurrent::doit() { | |
183 assert(Thread::current()->is_VM_thread(), "Should be VM thread"); | |
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184 assert(GCLockerInvokesConcurrent || ExplicitGCInvokesConcurrent, "Unexpected"); |
0 | 185 |
186 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
187 if (_gc_count_before == gch->total_collections()) { | |
188 // The "full" of do_full_collection call below "forces" | |
189 // a collection; the second arg, 0, below ensures that | |
190 // only the young gen is collected. XXX In the future, | |
191 // we'll probably need to have something in this interface | |
192 // to say do this only if we are sure we will not bail | |
193 // out to a full collection in this attempt, but that's | |
194 // for the future. | |
195 assert(SafepointSynchronize::is_at_safepoint(), | |
196 "We can only be executing this arm of if at a safepoint"); | |
197 GCCauseSetter gccs(gch, _gc_cause); | |
198 gch->do_full_collection(gch->must_clear_all_soft_refs(), | |
199 0 /* collect only youngest gen */); | |
200 } // Else no need for a foreground young gc | |
201 assert((_gc_count_before < gch->total_collections()) || | |
202 (GC_locker::is_active() /* gc may have been skipped */ | |
203 && (_gc_count_before == gch->total_collections())), | |
204 "total_collections() should be monotonically increasing"); | |
205 | |
206 MutexLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag); | |
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207 assert(_full_gc_count_before <= gch->total_full_collections(), "Error"); |
0 | 208 if (gch->total_full_collections() == _full_gc_count_before) { |
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209 // Disable iCMS until the full collection is done, and |
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210 // remember that we did so. |
0 | 211 CMSCollector::disable_icms(); |
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212 _disabled_icms = true; |
0 | 213 // In case CMS thread was in icms_wait(), wake it up. |
214 CMSCollector::start_icms(); | |
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215 // Nudge the CMS thread to start a concurrent collection. |
10405 | 216 CMSCollector::request_full_gc(_full_gc_count_before, _gc_cause); |
0 | 217 } else { |
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218 assert(_full_gc_count_before < gch->total_full_collections(), "Error"); |
0 | 219 FullGCCount_lock->notify_all(); // Inform the Java thread its work is done |
220 } | |
221 } | |
222 | |
223 bool VM_GenCollectFullConcurrent::evaluate_at_safepoint() const { | |
224 Thread* thr = Thread::current(); | |
225 assert(thr != NULL, "Unexpected tid"); | |
226 if (!thr->is_Java_thread()) { | |
227 assert(thr->is_VM_thread(), "Expected to be evaluated by VM thread"); | |
228 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
229 if (_gc_count_before != gch->total_collections()) { | |
230 // No need to do a young gc, we'll just nudge the CMS thread | |
231 // in the doit() method above, to be executed soon. | |
232 assert(_gc_count_before < gch->total_collections(), | |
14358 | 233 "total_collections() should be monotonically increasing"); |
0 | 234 return false; // no need for foreground young gc |
235 } | |
236 } | |
237 return true; // may still need foreground young gc | |
238 } | |
239 | |
240 | |
241 void VM_GenCollectFullConcurrent::doit_epilogue() { | |
242 Thread* thr = Thread::current(); | |
243 assert(thr->is_Java_thread(), "just checking"); | |
244 JavaThread* jt = (JavaThread*)thr; | |
245 // Release the Heap_lock first. | |
246 Heap_lock->unlock(); | |
247 release_and_notify_pending_list_lock(); | |
248 | |
249 // It is fine to test whether completed collections has | |
250 // exceeded our request count without locking because | |
251 // the completion count is monotonically increasing; | |
252 // this will break for very long-running apps when the | |
253 // count overflows and wraps around. XXX fix me !!! | |
254 // e.g. at the rate of 1 full gc per ms, this could | |
255 // overflow in about 1000 years. | |
256 GenCollectedHeap* gch = GenCollectedHeap::heap(); | |
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257 if (_gc_cause != GCCause::_gc_locker && |
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258 gch->total_full_collections_completed() <= _full_gc_count_before) { |
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259 // maybe we should change the condition to test _gc_cause == |
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260 // GCCause::_java_lang_system_gc, instead of |
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261 // _gc_cause != GCCause::_gc_locker |
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262 assert(_gc_cause == GCCause::_java_lang_system_gc, |
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263 "the only way to get here if this was a System.gc()-induced GC"); |
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264 assert(ExplicitGCInvokesConcurrent, "Error"); |
0 | 265 // Now, wait for witnessing concurrent gc cycle to complete, |
266 // but do so in native mode, because we want to lock the | |
267 // FullGCEvent_lock, which may be needed by the VM thread | |
268 // or by the CMS thread, so we do not want to be suspended | |
269 // while holding that lock. | |
270 ThreadToNativeFromVM native(jt); | |
271 MutexLockerEx ml(FullGCCount_lock, Mutex::_no_safepoint_check_flag); | |
272 // Either a concurrent or a stop-world full gc is sufficient | |
273 // witness to our request. | |
274 while (gch->total_full_collections_completed() <= _full_gc_count_before) { | |
275 FullGCCount_lock->wait(Mutex::_no_safepoint_check_flag); | |
276 } | |
277 } | |
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278 // Enable iCMS back if we disabled it earlier. |
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279 if (_disabled_icms) { |
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280 CMSCollector::enable_icms(); |
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281 } |
0 | 282 } |