1 /*
2 * Copyright (c) 2021, 2022, 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
26 #include "precompiled.hpp"
27
28 #include "gc/shenandoah/shenandoahBarrierSet.hpp"
29 #include "gc/shenandoah/shenandoahClosures.inline.hpp"
30 #include "gc/shenandoah/shenandoahMark.inline.hpp"
31 #include "gc/shenandoah/shenandoahOopClosures.inline.hpp"
32 #include "gc/shenandoah/shenandoahReferenceProcessor.hpp"
33 #include "gc/shenandoah/shenandoahTaskqueue.inline.hpp"
34 #include "gc/shenandoah/shenandoahUtils.hpp"
35 #include "gc/shenandoah/shenandoahVerifier.hpp"
36
37 ShenandoahMarkRefsSuperClosure::ShenandoahMarkRefsSuperClosure(ShenandoahObjToScanQueue* q, ShenandoahReferenceProcessor* rp) :
38 MetadataVisitingOopIterateClosure(rp),
39 _queue(q),
40 _mark_context(ShenandoahHeap::heap()->marking_context()),
41 _weak(false)
42 { }
43
44 ShenandoahMark::ShenandoahMark() :
45 _task_queues(ShenandoahHeap::heap()->marking_context()->task_queues()) {
46 }
47
48 void ShenandoahMark::start_mark() {
49 if (!CodeCache::is_gc_marking_cycle_active()) {
50 CodeCache::on_gc_marking_cycle_start();
51 }
52 }
53
54 void ShenandoahMark::end_mark() {
55 // Unlike other GCs, we do not arm the nmethods
56 // when marking terminates.
57 CodeCache::on_gc_marking_cycle_finish();
58 }
59
60 void ShenandoahMark::clear() {
61 // Clean up marking stacks.
62 ShenandoahObjToScanQueueSet* queues = ShenandoahHeap::heap()->marking_context()->task_queues();
63 queues->clear();
64
65 // Cancel SATB buffers.
66 ShenandoahBarrierSet::satb_mark_queue_set().abandon_partial_marking();
67 }
68
69 template <ShenandoahGenerationType GENERATION, bool CANCELLABLE, StringDedupMode STRING_DEDUP>
70 void ShenandoahMark::mark_loop_prework(uint w, TaskTerminator *t, ShenandoahReferenceProcessor *rp, StringDedup::Requests* const req) {
71 ShenandoahObjToScanQueue* q = get_queue(w);
72
73 ShenandoahHeap* const heap = ShenandoahHeap::heap();
74 ShenandoahLiveData* ld = heap->get_liveness_cache(w);
75
76 // TODO: We can clean up this if we figure out how to do templated oop closures that
77 // play nice with specialized_oop_iterators.
78 if (heap->has_forwarded_objects()) {
79 using Closure = ShenandoahMarkUpdateRefsClosure<GENERATION>;
80 Closure cl(q, rp);
81 mark_loop_work<Closure, GENERATION, CANCELLABLE, STRING_DEDUP>(&cl, ld, w, t, req);
82 } else {
83 using Closure = ShenandoahMarkRefsClosure<GENERATION>;
84 Closure cl(q, rp);
85 mark_loop_work<Closure, GENERATION, CANCELLABLE, STRING_DEDUP>(&cl, ld, w, t, req);
86 }
87
88 heap->flush_liveness_cache(w);
89 }
90
91 template<bool CANCELLABLE, StringDedupMode STRING_DEDUP>
92 void ShenandoahMark::mark_loop(uint worker_id, TaskTerminator* terminator, ShenandoahReferenceProcessor *rp,
93 ShenandoahGenerationType generation, StringDedup::Requests* const req) {
94 mark_loop_prework<NON_GEN, CANCELLABLE, STRING_DEDUP>(worker_id, terminator, rp, req);
95 }
96
97 void ShenandoahMark::mark_loop(uint worker_id, TaskTerminator* terminator, ShenandoahReferenceProcessor *rp,
98 ShenandoahGenerationType generation, bool cancellable, StringDedupMode dedup_mode,
99 StringDedup::Requests* const req) {
100 if (cancellable) {
101 switch(dedup_mode) {
102 case NO_DEDUP:
103 mark_loop<true, NO_DEDUP>(worker_id, terminator, rp, generation, req);
104 break;
105 case ENQUEUE_DEDUP:
106 mark_loop<true, ENQUEUE_DEDUP>(worker_id, terminator, rp, generation, req);
107 break;
108 case ALWAYS_DEDUP:
109 mark_loop<true, ALWAYS_DEDUP>(worker_id, terminator, rp, generation, req);
110 break;
111 }
112 } else {
113 switch(dedup_mode) {
114 case NO_DEDUP:
115 mark_loop<false, NO_DEDUP>(worker_id, terminator, rp, generation, req);
116 break;
117 case ENQUEUE_DEDUP:
118 mark_loop<false, ENQUEUE_DEDUP>(worker_id, terminator, rp, generation, req);
119 break;
120 case ALWAYS_DEDUP:
121 mark_loop<false, ALWAYS_DEDUP>(worker_id, terminator, rp, generation, req);
122 break;
123 }
124 }
125 }
126
127 template <class T, ShenandoahGenerationType GENERATION, bool CANCELLABLE, StringDedupMode STRING_DEDUP>
128 void ShenandoahMark::mark_loop_work(T* cl, ShenandoahLiveData* live_data, uint worker_id, TaskTerminator *terminator, StringDedup::Requests* const req) {
129 uintx stride = ShenandoahMarkLoopStride;
130
131 ShenandoahHeap* heap = ShenandoahHeap::heap();
132 ShenandoahObjToScanQueueSet* queues = task_queues();
133 ShenandoahObjToScanQueue* q;
134 ShenandoahMarkTask t;
135
136 heap->ref_processor()->set_mark_closure(worker_id, cl);
137
138 /*
139 * Process outstanding queues, if any.
140 *
141 * There can be more queues than workers. To deal with the imbalance, we claim
142 * extra queues first. Since marking can push new tasks into the queue associated
143 * with this worker id, we come back to process this queue in the normal loop.
144 */
145 assert(queues->get_reserved() == heap->workers()->active_workers(),
146 "Need to reserve proper number of queues: reserved: %u, active: %u", queues->get_reserved(), heap->workers()->active_workers());
147
148 q = queues->claim_next();
149 while (q != nullptr) {
150 if (CANCELLABLE && heap->check_cancelled_gc_and_yield()) {
151 return;
152 }
153
154 for (uint i = 0; i < stride; i++) {
155 if (q->pop(t)) {
156 do_task<T, GENERATION, STRING_DEDUP>(q, cl, live_data, req, &t);
157 } else {
158 assert(q->is_empty(), "Must be empty");
159 q = queues->claim_next();
160 break;
161 }
162 }
163 }
164 q = get_queue(worker_id);
165
166 ShenandoahSATBBufferClosure<GENERATION> drain_satb(q);
167 SATBMarkQueueSet& satb_mq_set = ShenandoahBarrierSet::satb_mark_queue_set();
168
169 /*
170 * Normal marking loop:
171 */
172 while (true) {
173 if (CANCELLABLE && heap->check_cancelled_gc_and_yield()) {
174 return;
175 }
176
177 while (satb_mq_set.completed_buffers_num() > 0) {
178 satb_mq_set.apply_closure_to_completed_buffer(&drain_satb);
179 }
180
181 uint work = 0;
182 for (uint i = 0; i < stride; i++) {
183 if (q->pop(t) ||
184 queues->steal(worker_id, t)) {
185 do_task<T, GENERATION, STRING_DEDUP>(q, cl, live_data, req, &t);
186 work++;
187 } else {
188 break;
189 }
190 }
191
192 if (work == 0) {
193 // No work encountered in current stride, try to terminate.
194 // Need to leave the STS here otherwise it might block safepoints.
195 ShenandoahSuspendibleThreadSetLeaver stsl(CANCELLABLE);
196 ShenandoahTerminatorTerminator tt(heap);
197 if (terminator->offer_termination(&tt)) return;
198 }
199 }
200 }