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comparison src/share/vm/gc_implementation/concurrentMarkSweep/vmCMSOperations.cpp @ 0:a61af66fc99e jdk7-b24

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author duke
date Sat, 01 Dec 2007 00:00:00 +0000
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-1:000000000000 0:a61af66fc99e
1 /*
2 * Copyright 2005-2006 Sun Microsystems, Inc. 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
20 * CA 95054 USA or visit www.sun.com if you need additional information or
21 * have any questions.
22 *
23 */
24 # include "incls/_precompiled.incl"
25 # include "incls/_vmCMSOperations.cpp.incl"
26
27 HS_DTRACE_PROBE_DECL(hs_private, cms__initmark__begin);
28 HS_DTRACE_PROBE_DECL(hs_private, cms__initmark__end);
29
30 HS_DTRACE_PROBE_DECL(hs_private, cms__remark__begin);
31 HS_DTRACE_PROBE_DECL(hs_private, cms__remark__end);
32
33 //////////////////////////////////////////////////////////
34 // Methods in abstract class VM_CMS_Operation
35 //////////////////////////////////////////////////////////
36 void VM_CMS_Operation::acquire_pending_list_lock() {
37 // The caller may block while communicating
38 // with the SLT thread in order to acquire/release the PLL.
39 ConcurrentMarkSweepThread::slt()->
40 manipulatePLL(SurrogateLockerThread::acquirePLL);
41 }
42
43 void VM_CMS_Operation::release_and_notify_pending_list_lock() {
44 // The caller may block while communicating
45 // with the SLT thread in order to acquire/release the PLL.
46 ConcurrentMarkSweepThread::slt()->
47 manipulatePLL(SurrogateLockerThread::releaseAndNotifyPLL);
48 }
49
50 void VM_CMS_Operation::verify_before_gc() {
51 if (VerifyBeforeGC &&
52 GenCollectedHeap::heap()->total_collections() >= VerifyGCStartAt) {
53 HandleMark hm;
54 FreelistLocker x(_collector);
55 MutexLockerEx y(_collector->bitMapLock(), Mutex::_no_safepoint_check_flag);
56 Universe::heap()->prepare_for_verify();
57 Universe::verify(true);
58 }
59 }
60
61 void VM_CMS_Operation::verify_after_gc() {
62 if (VerifyAfterGC &&
63 GenCollectedHeap::heap()->total_collections() >= VerifyGCStartAt) {
64 HandleMark hm;
65 FreelistLocker x(_collector);
66 MutexLockerEx y(_collector->bitMapLock(), Mutex::_no_safepoint_check_flag);
67 Universe::verify(true);
68 }
69 }
70
71 bool VM_CMS_Operation::lost_race() const {
72 if (CMSCollector::abstract_state() == CMSCollector::Idling) {
73 // We lost a race to a foreground collection
74 // -- there's nothing to do
75 return true;
76 }
77 assert(CMSCollector::abstract_state() == legal_state(),
78 "Inconsistent collector state?");
79 return false;
80 }
81
82 bool VM_CMS_Operation::doit_prologue() {
83 assert(Thread::current()->is_ConcurrentGC_thread(), "just checking");
84 assert(!CMSCollector::foregroundGCShouldWait(), "Possible deadlock");
85 assert(!ConcurrentMarkSweepThread::cms_thread_has_cms_token(),
86 "Possible deadlock");
87
88 if (needs_pll()) {
89 acquire_pending_list_lock();
90 }
91 // Get the Heap_lock after the pending_list_lock.
92 Heap_lock->lock();
93 if (lost_race()) {
94 assert(_prologue_succeeded == false, "Initialized in c'tor");
95 Heap_lock->unlock();
96 if (needs_pll()) {
97 release_and_notify_pending_list_lock();
98 }
99 } else {
100 _prologue_succeeded = true;
101 }
102 return _prologue_succeeded;
103 }
104
105 void VM_CMS_Operation::doit_epilogue() {
106 assert(Thread::current()->is_ConcurrentGC_thread(), "just checking");
107 assert(!CMSCollector::foregroundGCShouldWait(), "Possible deadlock");
108 assert(!ConcurrentMarkSweepThread::cms_thread_has_cms_token(),
109 "Possible deadlock");
110
111 // Release the Heap_lock first.
112 Heap_lock->unlock();
113 if (needs_pll()) {
114 release_and_notify_pending_list_lock();
115 }
116 }
117
118 //////////////////////////////////////////////////////////
119 // Methods in class VM_CMS_Initial_Mark
120 //////////////////////////////////////////////////////////
121 void VM_CMS_Initial_Mark::doit() {
122 if (lost_race()) {
123 // Nothing to do.
124 return;
125 }
126 HS_DTRACE_PROBE(hs_private, cms__initmark__begin);
127
128 GenCollectedHeap* gch = GenCollectedHeap::heap();
129 GCCauseSetter gccs(gch, GCCause::_cms_initial_mark);
130
131 VM_CMS_Operation::verify_before_gc();
132
133 IsGCActiveMark x; // stop-world GC active
134 _collector->do_CMS_operation(CMSCollector::CMS_op_checkpointRootsInitial);
135
136 VM_CMS_Operation::verify_after_gc();
137 HS_DTRACE_PROBE(hs_private, cms__initmark__end);
138 }
139
140 //////////////////////////////////////////////////////////
141 // Methods in class VM_CMS_Final_Remark_Operation
142 //////////////////////////////////////////////////////////
143 void VM_CMS_Final_Remark::doit() {
144 if (lost_race()) {
145 // Nothing to do.
146 return;
147 }
148 HS_DTRACE_PROBE(hs_private, cms__remark__begin);
149
150 GenCollectedHeap* gch = GenCollectedHeap::heap();
151 GCCauseSetter gccs(gch, GCCause::_cms_final_remark);
152
153 VM_CMS_Operation::verify_before_gc();
154
155 IsGCActiveMark x; // stop-world GC active
156 _collector->do_CMS_operation(CMSCollector::CMS_op_checkpointRootsFinal);
157
158 VM_CMS_Operation::verify_after_gc();
159 HS_DTRACE_PROBE(hs_private, cms__remark__end);
160 }
161
162 // VM operation to invoke a concurrent collection of a
163 // GenCollectedHeap heap.
164 void VM_GenCollectFullConcurrent::doit() {
165 assert(Thread::current()->is_VM_thread(), "Should be VM thread");
166
167 GenCollectedHeap* gch = GenCollectedHeap::heap();
168 if (_gc_count_before == gch->total_collections()) {
169 // The "full" of do_full_collection call below "forces"
170 // a collection; the second arg, 0, below ensures that
171 // only the young gen is collected. XXX In the future,
172 // we'll probably need to have something in this interface
173 // to say do this only if we are sure we will not bail
174 // out to a full collection in this attempt, but that's
175 // for the future.
176 assert(SafepointSynchronize::is_at_safepoint(),
177 "We can only be executing this arm of if at a safepoint");
178 GCCauseSetter gccs(gch, _gc_cause);
179 gch->do_full_collection(gch->must_clear_all_soft_refs(),
180 0 /* collect only youngest gen */);
181 } // Else no need for a foreground young gc
182 assert((_gc_count_before < gch->total_collections()) ||
183 (GC_locker::is_active() /* gc may have been skipped */
184 && (_gc_count_before == gch->total_collections())),
185 "total_collections() should be monotonically increasing");
186
187 MutexLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
188 if (gch->total_full_collections() == _full_gc_count_before) {
189 // Disable iCMS until the full collection is done.
190 CMSCollector::disable_icms();
191 // In case CMS thread was in icms_wait(), wake it up.
192 CMSCollector::start_icms();
193 // Nudge the CMS thread to start a concurrent collection
194 CMSCollector::request_full_gc(_full_gc_count_before);
195 } else {
196 FullGCCount_lock->notify_all(); // Inform the Java thread its work is done
197 }
198 }
199
200 bool VM_GenCollectFullConcurrent::evaluate_at_safepoint() const {
201 Thread* thr = Thread::current();
202 assert(thr != NULL, "Unexpected tid");
203 if (!thr->is_Java_thread()) {
204 assert(thr->is_VM_thread(), "Expected to be evaluated by VM thread");
205 GenCollectedHeap* gch = GenCollectedHeap::heap();
206 if (_gc_count_before != gch->total_collections()) {
207 // No need to do a young gc, we'll just nudge the CMS thread
208 // in the doit() method above, to be executed soon.
209 assert(_gc_count_before < gch->total_collections(),
210 "total_collections() should be monotnically increasing");
211 return false; // no need for foreground young gc
212 }
213 }
214 return true; // may still need foreground young gc
215 }
216
217
218 void VM_GenCollectFullConcurrent::doit_epilogue() {
219 Thread* thr = Thread::current();
220 assert(thr->is_Java_thread(), "just checking");
221 JavaThread* jt = (JavaThread*)thr;
222 // Release the Heap_lock first.
223 Heap_lock->unlock();
224 release_and_notify_pending_list_lock();
225
226 // It is fine to test whether completed collections has
227 // exceeded our request count without locking because
228 // the completion count is monotonically increasing;
229 // this will break for very long-running apps when the
230 // count overflows and wraps around. XXX fix me !!!
231 // e.g. at the rate of 1 full gc per ms, this could
232 // overflow in about 1000 years.
233 GenCollectedHeap* gch = GenCollectedHeap::heap();
234 if (gch->total_full_collections_completed() <= _full_gc_count_before) {
235 // Now, wait for witnessing concurrent gc cycle to complete,
236 // but do so in native mode, because we want to lock the
237 // FullGCEvent_lock, which may be needed by the VM thread
238 // or by the CMS thread, so we do not want to be suspended
239 // while holding that lock.
240 ThreadToNativeFromVM native(jt);
241 MutexLockerEx ml(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
242 // Either a concurrent or a stop-world full gc is sufficient
243 // witness to our request.
244 while (gch->total_full_collections_completed() <= _full_gc_count_before) {
245 FullGCCount_lock->wait(Mutex::_no_safepoint_check_flag);
246 }
247 }
248 // Enable iCMS back.
249 CMSCollector::enable_icms();
250 }