| File: | jdk/src/hotspot/share/gc/shenandoah/shenandoahConcurrentMark.cpp |
| Warning: | line 59, column 31 Value stored to 'q' during its initialization is never read |
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| 1 | /* |
| 2 | * Copyright (c) 2013, 2021, Red Hat, 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 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 | |
| 27 | #include "gc/shared/satbMarkQueue.hpp" |
| 28 | #include "gc/shared/strongRootsScope.hpp" |
| 29 | #include "gc/shared/taskTerminator.hpp" |
| 30 | #include "gc/shenandoah/shenandoahBarrierSet.inline.hpp" |
| 31 | #include "gc/shenandoah/shenandoahClosures.inline.hpp" |
| 32 | #include "gc/shenandoah/shenandoahConcurrentMark.hpp" |
| 33 | #include "gc/shenandoah/shenandoahHeap.inline.hpp" |
| 34 | #include "gc/shenandoah/shenandoahMark.inline.hpp" |
| 35 | #include "gc/shenandoah/shenandoahReferenceProcessor.hpp" |
| 36 | #include "gc/shenandoah/shenandoahRootProcessor.inline.hpp" |
| 37 | #include "gc/shenandoah/shenandoahOopClosures.inline.hpp" |
| 38 | #include "gc/shenandoah/shenandoahPhaseTimings.hpp" |
| 39 | #include "gc/shenandoah/shenandoahStringDedup.hpp" |
| 40 | #include "gc/shenandoah/shenandoahTaskqueue.inline.hpp" |
| 41 | #include "gc/shenandoah/shenandoahUtils.hpp" |
| 42 | #include "memory/iterator.inline.hpp" |
| 43 | #include "memory/resourceArea.hpp" |
| 44 | |
| 45 | class ShenandoahConcurrentMarkingTask : public WorkerTask { |
| 46 | private: |
| 47 | ShenandoahConcurrentMark* const _cm; |
| 48 | TaskTerminator* const _terminator; |
| 49 | |
| 50 | public: |
| 51 | ShenandoahConcurrentMarkingTask(ShenandoahConcurrentMark* cm, TaskTerminator* terminator) : |
| 52 | WorkerTask("Shenandoah Concurrent Mark"), _cm(cm), _terminator(terminator) { |
| 53 | } |
| 54 | |
| 55 | void work(uint worker_id) { |
| 56 | ShenandoahHeap* heap = ShenandoahHeap::heap(); |
| 57 | ShenandoahConcurrentWorkerSession worker_session(worker_id); |
| 58 | ShenandoahSuspendibleThreadSetJoiner stsj(ShenandoahSuspendibleWorkers); |
| 59 | ShenandoahObjToScanQueue* q = _cm->get_queue(worker_id); |
Value stored to 'q' during its initialization is never read | |
| 60 | ShenandoahReferenceProcessor* rp = heap->ref_processor(); |
| 61 | assert(rp != NULL, "need reference processor")do { if (!(rp != __null)) { (*g_assert_poison) = 'X';; report_vm_error ("/home/daniel/Projects/java/jdk/src/hotspot/share/gc/shenandoah/shenandoahConcurrentMark.cpp" , 61, "assert(" "rp != __null" ") failed", "need reference processor" ); ::breakpoint(); } } while (0); |
| 62 | StringDedup::Requests requests; |
| 63 | _cm->mark_loop(worker_id, _terminator, rp, |
| 64 | true /*cancellable*/, |
| 65 | ShenandoahStringDedup::is_enabled() ? ENQUEUE_DEDUP : NO_DEDUP, |
| 66 | &requests); |
| 67 | } |
| 68 | }; |
| 69 | |
| 70 | class ShenandoahSATBAndRemarkThreadsClosure : public ThreadClosure { |
| 71 | private: |
| 72 | SATBMarkQueueSet& _satb_qset; |
| 73 | OopClosure* const _cl; |
| 74 | uintx _claim_token; |
| 75 | |
| 76 | public: |
| 77 | ShenandoahSATBAndRemarkThreadsClosure(SATBMarkQueueSet& satb_qset, OopClosure* cl) : |
| 78 | _satb_qset(satb_qset), |
| 79 | _cl(cl), |
| 80 | _claim_token(Threads::thread_claim_token()) {} |
| 81 | |
| 82 | void do_thread(Thread* thread) { |
| 83 | if (thread->claim_threads_do(true, _claim_token)) { |
| 84 | // Transfer any partial buffer to the qset for completed buffer processing. |
| 85 | _satb_qset.flush_queue(ShenandoahThreadLocalData::satb_mark_queue(thread)); |
| 86 | if (thread->is_Java_thread()) { |
| 87 | if (_cl != NULL__null) { |
| 88 | ResourceMark rm; |
| 89 | thread->oops_do(_cl, NULL__null); |
| 90 | } |
| 91 | } |
| 92 | } |
| 93 | } |
| 94 | }; |
| 95 | |
| 96 | class ShenandoahFinalMarkingTask : public WorkerTask { |
| 97 | private: |
| 98 | ShenandoahConcurrentMark* _cm; |
| 99 | TaskTerminator* _terminator; |
| 100 | bool _dedup_string; |
| 101 | |
| 102 | public: |
| 103 | ShenandoahFinalMarkingTask(ShenandoahConcurrentMark* cm, TaskTerminator* terminator, bool dedup_string) : |
| 104 | WorkerTask("Shenandoah Final Mark"), _cm(cm), _terminator(terminator), _dedup_string(dedup_string) { |
| 105 | } |
| 106 | |
| 107 | void work(uint worker_id) { |
| 108 | ShenandoahHeap* heap = ShenandoahHeap::heap(); |
| 109 | |
| 110 | ShenandoahParallelWorkerSession worker_session(worker_id); |
| 111 | ShenandoahReferenceProcessor* rp = heap->ref_processor(); |
| 112 | StringDedup::Requests requests; |
| 113 | |
| 114 | // First drain remaining SATB buffers. |
| 115 | { |
| 116 | ShenandoahObjToScanQueue* q = _cm->get_queue(worker_id); |
| 117 | |
| 118 | ShenandoahSATBBufferClosure cl(q); |
| 119 | SATBMarkQueueSet& satb_mq_set = ShenandoahBarrierSet::satb_mark_queue_set(); |
| 120 | while (satb_mq_set.apply_closure_to_completed_buffer(&cl)) {} |
| 121 | assert(!heap->has_forwarded_objects(), "Not expected")do { if (!(!heap->has_forwarded_objects())) { (*g_assert_poison ) = 'X';; report_vm_error("/home/daniel/Projects/java/jdk/src/hotspot/share/gc/shenandoah/shenandoahConcurrentMark.cpp" , 121, "assert(" "!heap->has_forwarded_objects()" ") failed" , "Not expected"); ::breakpoint(); } } while (0); |
| 122 | |
| 123 | ShenandoahMarkRefsClosure mark_cl(q, rp); |
| 124 | ShenandoahSATBAndRemarkThreadsClosure tc(satb_mq_set, |
| 125 | ShenandoahIUBarrier ? &mark_cl : NULL__null); |
| 126 | Threads::threads_do(&tc); |
| 127 | } |
| 128 | _cm->mark_loop(worker_id, _terminator, rp, |
| 129 | false /*not cancellable*/, |
| 130 | _dedup_string ? ENQUEUE_DEDUP : NO_DEDUP, |
| 131 | &requests); |
| 132 | assert(_cm->task_queues()->is_empty(), "Should be empty")do { if (!(_cm->task_queues()->is_empty())) { (*g_assert_poison ) = 'X';; report_vm_error("/home/daniel/Projects/java/jdk/src/hotspot/share/gc/shenandoah/shenandoahConcurrentMark.cpp" , 132, "assert(" "_cm->task_queues()->is_empty()" ") failed" , "Should be empty"); ::breakpoint(); } } while (0); |
| 133 | } |
| 134 | }; |
| 135 | |
| 136 | ShenandoahConcurrentMark::ShenandoahConcurrentMark() : |
| 137 | ShenandoahMark() {} |
| 138 | |
| 139 | // Mark concurrent roots during concurrent phases |
| 140 | class ShenandoahMarkConcurrentRootsTask : public WorkerTask { |
| 141 | private: |
| 142 | SuspendibleThreadSetJoiner _sts_joiner; |
| 143 | ShenandoahConcurrentRootScanner _root_scanner; |
| 144 | ShenandoahObjToScanQueueSet* const _queue_set; |
| 145 | ShenandoahReferenceProcessor* const _rp; |
| 146 | |
| 147 | public: |
| 148 | ShenandoahMarkConcurrentRootsTask(ShenandoahObjToScanQueueSet* qs, |
| 149 | ShenandoahReferenceProcessor* rp, |
| 150 | ShenandoahPhaseTimings::Phase phase, |
| 151 | uint nworkers); |
| 152 | void work(uint worker_id); |
| 153 | }; |
| 154 | |
| 155 | ShenandoahMarkConcurrentRootsTask::ShenandoahMarkConcurrentRootsTask(ShenandoahObjToScanQueueSet* qs, |
| 156 | ShenandoahReferenceProcessor* rp, |
| 157 | ShenandoahPhaseTimings::Phase phase, |
| 158 | uint nworkers) : |
| 159 | WorkerTask("Shenandoah Concurrent Mark Roots"), |
| 160 | _root_scanner(nworkers, phase), |
| 161 | _queue_set(qs), |
| 162 | _rp(rp) { |
| 163 | assert(!ShenandoahHeap::heap()->has_forwarded_objects(), "Not expected")do { if (!(!ShenandoahHeap::heap()->has_forwarded_objects( ))) { (*g_assert_poison) = 'X';; report_vm_error("/home/daniel/Projects/java/jdk/src/hotspot/share/gc/shenandoah/shenandoahConcurrentMark.cpp" , 163, "assert(" "!ShenandoahHeap::heap()->has_forwarded_objects()" ") failed", "Not expected"); ::breakpoint(); } } while (0); |
| 164 | } |
| 165 | |
| 166 | void ShenandoahMarkConcurrentRootsTask::work(uint worker_id) { |
| 167 | ShenandoahConcurrentWorkerSession worker_session(worker_id); |
| 168 | ShenandoahObjToScanQueue* q = _queue_set->queue(worker_id); |
| 169 | ShenandoahMarkRefsClosure cl(q, _rp); |
| 170 | _root_scanner.roots_do(&cl, worker_id); |
| 171 | } |
| 172 | |
| 173 | void ShenandoahConcurrentMark::mark_concurrent_roots() { |
| 174 | ShenandoahHeap* const heap = ShenandoahHeap::heap(); |
| 175 | assert(!heap->has_forwarded_objects(), "Not expected")do { if (!(!heap->has_forwarded_objects())) { (*g_assert_poison ) = 'X';; report_vm_error("/home/daniel/Projects/java/jdk/src/hotspot/share/gc/shenandoah/shenandoahConcurrentMark.cpp" , 175, "assert(" "!heap->has_forwarded_objects()" ") failed" , "Not expected"); ::breakpoint(); } } while (0); |
| 176 | |
| 177 | TASKQUEUE_STATS_ONLY(task_queues()->reset_taskqueue_stats())task_queues()->reset_taskqueue_stats(); |
| 178 | |
| 179 | WorkerThreads* workers = heap->workers(); |
| 180 | ShenandoahReferenceProcessor* rp = heap->ref_processor(); |
| 181 | task_queues()->reserve(workers->active_workers()); |
| 182 | ShenandoahMarkConcurrentRootsTask task(task_queues(), rp, ShenandoahPhaseTimings::conc_mark_roots, workers->active_workers()); |
| 183 | |
| 184 | workers->run_task(&task); |
| 185 | } |
| 186 | |
| 187 | class ShenandoahFlushSATBHandshakeClosure : public HandshakeClosure { |
| 188 | private: |
| 189 | SATBMarkQueueSet& _qset; |
| 190 | public: |
| 191 | ShenandoahFlushSATBHandshakeClosure(SATBMarkQueueSet& qset) : |
| 192 | HandshakeClosure("Shenandoah Flush SATB Handshake"), |
| 193 | _qset(qset) {} |
| 194 | |
| 195 | void do_thread(Thread* thread) { |
| 196 | _qset.flush_queue(ShenandoahThreadLocalData::satb_mark_queue(thread)); |
| 197 | } |
| 198 | }; |
| 199 | |
| 200 | void ShenandoahConcurrentMark::concurrent_mark() { |
| 201 | ShenandoahHeap* const heap = ShenandoahHeap::heap(); |
| 202 | WorkerThreads* workers = heap->workers(); |
| 203 | uint nworkers = workers->active_workers(); |
| 204 | task_queues()->reserve(nworkers); |
| 205 | |
| 206 | ShenandoahSATBMarkQueueSet& qset = ShenandoahBarrierSet::satb_mark_queue_set(); |
| 207 | ShenandoahFlushSATBHandshakeClosure flush_satb(qset); |
| 208 | for (uint flushes = 0; flushes < ShenandoahMaxSATBBufferFlushes; flushes++) { |
| 209 | TaskTerminator terminator(nworkers, task_queues()); |
| 210 | ShenandoahConcurrentMarkingTask task(this, &terminator); |
| 211 | workers->run_task(&task); |
| 212 | |
| 213 | if (heap->cancelled_gc()) { |
| 214 | // GC is cancelled, break out. |
| 215 | break; |
| 216 | } |
| 217 | |
| 218 | size_t before = qset.completed_buffers_num(); |
| 219 | Handshake::execute(&flush_satb); |
| 220 | size_t after = qset.completed_buffers_num(); |
| 221 | |
| 222 | if (before == after) { |
| 223 | // No more retries needed, break out. |
| 224 | break; |
| 225 | } |
| 226 | } |
| 227 | assert(task_queues()->is_empty() || heap->cancelled_gc(), "Should be empty when not cancelled")do { if (!(task_queues()->is_empty() || heap->cancelled_gc ())) { (*g_assert_poison) = 'X';; report_vm_error("/home/daniel/Projects/java/jdk/src/hotspot/share/gc/shenandoah/shenandoahConcurrentMark.cpp" , 227, "assert(" "task_queues()->is_empty() || heap->cancelled_gc()" ") failed", "Should be empty when not cancelled"); ::breakpoint (); } } while (0); |
| 228 | } |
| 229 | |
| 230 | void ShenandoahConcurrentMark::finish_mark() { |
| 231 | assert(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "Must be at a safepoint")do { if (!(ShenandoahSafepoint::is_at_shenandoah_safepoint()) ) { (*g_assert_poison) = 'X';; report_vm_error("/home/daniel/Projects/java/jdk/src/hotspot/share/gc/shenandoah/shenandoahConcurrentMark.cpp" , 231, "assert(" "ShenandoahSafepoint::is_at_shenandoah_safepoint()" ") failed", "Must be at a safepoint"); ::breakpoint(); } } while (0); |
| 232 | assert(Thread::current()->is_VM_thread(), "Must by VM Thread")do { if (!(Thread::current()->is_VM_thread())) { (*g_assert_poison ) = 'X';; report_vm_error("/home/daniel/Projects/java/jdk/src/hotspot/share/gc/shenandoah/shenandoahConcurrentMark.cpp" , 232, "assert(" "Thread::current()->is_VM_thread()" ") failed" , "Must by VM Thread"); ::breakpoint(); } } while (0); |
| 233 | finish_mark_work(); |
| 234 | assert(task_queues()->is_empty(), "Should be empty")do { if (!(task_queues()->is_empty())) { (*g_assert_poison ) = 'X';; report_vm_error("/home/daniel/Projects/java/jdk/src/hotspot/share/gc/shenandoah/shenandoahConcurrentMark.cpp" , 234, "assert(" "task_queues()->is_empty()" ") failed", "Should be empty" ); ::breakpoint(); } } while (0); |
| 235 | TASKQUEUE_STATS_ONLY(task_queues()->print_taskqueue_stats())task_queues()->print_taskqueue_stats(); |
| 236 | TASKQUEUE_STATS_ONLY(task_queues()->reset_taskqueue_stats())task_queues()->reset_taskqueue_stats(); |
| 237 | |
| 238 | ShenandoahHeap* const heap = ShenandoahHeap::heap(); |
| 239 | heap->set_concurrent_mark_in_progress(false); |
| 240 | heap->mark_complete_marking_context(); |
| 241 | } |
| 242 | |
| 243 | void ShenandoahConcurrentMark::finish_mark_work() { |
| 244 | // Finally mark everything else we've got in our queues during the previous steps. |
| 245 | // It does two different things for concurrent vs. mark-compact GC: |
| 246 | // - For concurrent GC, it starts with empty task queues, drains the remaining |
| 247 | // SATB buffers, and then completes the marking closure. |
| 248 | // - For mark-compact GC, it starts out with the task queues seeded by initial |
| 249 | // root scan, and completes the closure, thus marking through all live objects |
| 250 | // The implementation is the same, so it's shared here. |
| 251 | ShenandoahHeap* const heap = ShenandoahHeap::heap(); |
| 252 | ShenandoahGCPhase phase(ShenandoahPhaseTimings::finish_mark); |
| 253 | uint nworkers = heap->workers()->active_workers(); |
| 254 | task_queues()->reserve(nworkers); |
| 255 | |
| 256 | StrongRootsScope scope(nworkers); |
| 257 | TaskTerminator terminator(nworkers, task_queues()); |
| 258 | ShenandoahFinalMarkingTask task(this, &terminator, ShenandoahStringDedup::is_enabled()); |
| 259 | heap->workers()->run_task(&task); |
| 260 | |
| 261 | assert(task_queues()->is_empty(), "Should be empty")do { if (!(task_queues()->is_empty())) { (*g_assert_poison ) = 'X';; report_vm_error("/home/daniel/Projects/java/jdk/src/hotspot/share/gc/shenandoah/shenandoahConcurrentMark.cpp" , 261, "assert(" "task_queues()->is_empty()" ") failed", "Should be empty" ); ::breakpoint(); } } while (0); |
| 262 | } |
| 263 | |
| 264 | |
| 265 | void ShenandoahConcurrentMark::cancel() { |
| 266 | clear(); |
| 267 | ShenandoahReferenceProcessor* rp = ShenandoahHeap::heap()->ref_processor(); |
| 268 | rp->abandon_partial_discovery(); |
| 269 | } |