1 /*
2 * Copyright (c) 2017, 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/cms/concurrentMarkSweepThread.hpp"
27 #include "gc/cms/cmsHeap.hpp"
28 #include "gc/cms/vmCMSOperations.hpp"
29 #include "gc/shared/genOopClosures.inline.hpp"
30 #include "gc/shared/strongRootsScope.hpp"
31 #include "gc/shared/workgroup.hpp"
32 #include "oops/oop.inline.hpp"
33 #include "runtime/vmThread.hpp"
34 #include "utilities/stack.inline.hpp"
35
36 CMSHeap::CMSHeap(GenCollectorPolicy *policy) : GenCollectedHeap(policy) {
37 _workers = new WorkGang("GC Thread", ParallelGCThreads,
38 /* are_GC_task_threads */true,
39 /* are_ConcurrentGC_threads */false);
40 _workers->initialize_workers();
41 }
42
43 jint CMSHeap::initialize() {
44 jint status = GenCollectedHeap::initialize();
45 if (status != JNI_OK) return status;
46
47 // If we are running CMS, create the collector responsible
48 // for collecting the CMS generations.
49 assert(collector_policy()->is_concurrent_mark_sweep_policy(), "must be CMS policy");
50 if (!create_cms_collector()) {
51 return JNI_ENOMEM;
52 }
53
54 return JNI_OK;
55 }
56
57 void CMSHeap::check_gen_kinds() {
58 assert(young_gen()->kind() == Generation::ParNew,
59 "Wrong youngest generation type");
60 assert(old_gen()->kind() == Generation::ConcurrentMarkSweep,
61 "Wrong generation kind");
62 }
63
64 CMSHeap* CMSHeap::heap() {
65 CollectedHeap* heap = Universe::heap();
66 assert(heap != NULL, "Uninitialized access to CMSHeap::heap()");
67 assert(heap->kind() == CollectedHeap::CMSHeap, "Not a CMSHeap");
68 return (CMSHeap*) heap;
69 }
70
71 void CMSHeap::gc_threads_do(ThreadClosure* tc) const {
72 assert(workers() != NULL, "should have workers here");
73 workers()->threads_do(tc);
74 ConcurrentMarkSweepThread::threads_do(tc);
75 }
76
77 void CMSHeap::print_gc_threads_on(outputStream* st) const {
78 assert(workers() != NULL, "should have workers here");
79 workers()->print_worker_threads_on(st);
80 ConcurrentMarkSweepThread::print_all_on(st);
81 }
82
83 void CMSHeap::print_on_error(outputStream* st) const {
84 GenCollectedHeap::print_on_error(st);
85 st->cr();
86 CMSCollector::print_on_error(st);
87 }
88
89 bool CMSHeap::create_cms_collector() {
90 assert(old_gen()->kind() == Generation::ConcurrentMarkSweep,
91 "Unexpected generation kinds");
92 assert(gen_policy()->is_concurrent_mark_sweep_policy(), "Unexpected policy type");
93 CMSCollector* collector =
94 new CMSCollector((ConcurrentMarkSweepGeneration*) old_gen(),
95 rem_set(),
96 gen_policy()->as_concurrent_mark_sweep_policy());
97
98 if (collector == NULL || !collector->completed_initialization()) {
99 if (collector) {
100 delete collector; // Be nice in embedded situation
101 }
102 vm_shutdown_during_initialization("Could not create CMS collector");
103 return false;
104 }
105 return true; // success
106 }
107
108 void CMSHeap::collect(GCCause::Cause cause) {
109 if (should_do_concurrent_full_gc(cause)) {
110 // Mostly concurrent full collection.
111 collect_mostly_concurrent(cause);
112 } else {
113 GenCollectedHeap::collect(cause);
114 }
115 }
116
117 bool CMSHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
118 switch (cause) {
119 case GCCause::_gc_locker: return GCLockerInvokesConcurrent;
120 case GCCause::_java_lang_system_gc:
121 case GCCause::_dcmd_gc_run: return ExplicitGCInvokesConcurrent;
122 default: return false;
123 }
124 }
125
126 void CMSHeap::collect_mostly_concurrent(GCCause::Cause cause) {
127 assert(!Heap_lock->owned_by_self(), "Should not own Heap_lock");
128
129 MutexLocker ml(Heap_lock);
130 // Read the GC counts while holding the Heap_lock
131 unsigned int full_gc_count_before = total_full_collections();
132 unsigned int gc_count_before = total_collections();
133 {
134 MutexUnlocker mu(Heap_lock);
135 VM_GenCollectFullConcurrent op(gc_count_before, full_gc_count_before, cause);
136 VMThread::execute(&op);
137 }
138 }
139
140 void CMSHeap::stop() {
141 ConcurrentMarkSweepThread::cmst()->stop();
142 }
143
144 void CMSHeap::safepoint_synchronize_begin() {
145 ConcurrentMarkSweepThread::synchronize(false);
146 }
147
148 void CMSHeap::safepoint_synchronize_end() {
149 ConcurrentMarkSweepThread::desynchronize(false);
150 }
151
152 void CMSHeap::cms_process_roots(StrongRootsScope* scope,
153 bool young_gen_as_roots,
154 ScanningOption so,
155 bool only_strong_roots,
156 OopsInGenClosure* root_closure,
157 CLDClosure* cld_closure) {
158 MarkingCodeBlobClosure mark_code_closure(root_closure, !CodeBlobToOopClosure::FixRelocations);
159 OopsInGenClosure* weak_roots = only_strong_roots ? NULL : root_closure;
160 CLDClosure* weak_cld_closure = only_strong_roots ? NULL : cld_closure;
161
162 process_roots(scope, so, root_closure, weak_roots, cld_closure, weak_cld_closure, &mark_code_closure);
163 if (!only_strong_roots) {
164 process_string_table_roots(scope, root_closure);
165 }
166
167 if (young_gen_as_roots &&
168 !_process_strong_tasks->is_task_claimed(GCH_PS_younger_gens)) {
169 root_closure->set_generation(young_gen());
170 young_gen()->oop_iterate(root_closure);
171 root_closure->reset_generation();
172 }
173
174 _process_strong_tasks->all_tasks_completed(scope->n_threads());
175 }
176
177 void CMSHeap::gc_prologue(bool full) {
178 always_do_update_barrier = false;
179 GenCollectedHeap::gc_prologue(full);
180 };
181
182 void CMSHeap::gc_epilogue(bool full) {
183 GenCollectedHeap::gc_epilogue(full);
184 always_do_update_barrier = true;
185 };