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 "gc/cms/concurrentMarkSweepThread.hpp"
26 #include "gc/cms/cmsHeap.hpp"
27 #include "gc/cms/vmCMSOperations.hpp"
28 #include "gc/shared/genOopClosures.inline.hpp"
29 #include "gc/shared/strongRootsScope.hpp"
30 #include "gc/shared/workgroup.hpp"
31 #include "oops/oop.inline.hpp"
32 #include "runtime/vmThread.hpp"
33 #include "utilities/stack.inline.hpp"
34
35 CMSHeap::CMSHeap(GenCollectorPolicy *policy) : GenCollectedHeap(policy) {
36
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 bool success = create_cms_collector();
51 if (!success) return JNI_ENOMEM;
52
53 return JNI_OK;
54 }
55
56 #ifdef ASSERT
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 #endif
64
65
66 CMSHeap* CMSHeap::heap() {
67 CollectedHeap* heap = Universe::heap();
68 assert(heap != NULL, "Uninitialized access to CMSHeap::heap()");
69 assert(heap->kind() == CollectedHeap::CMSHeap, "Not a CMSHeap");
70 return (CMSHeap*) heap;
71 }
72
73 void CMSHeap::gc_threads_do(ThreadClosure* tc) const {
74 assert(workers() != NULL, "should have workers here");
75 workers()->threads_do(tc);
76 ConcurrentMarkSweepThread::threads_do(tc);
77 }
78
79 void CMSHeap::print_gc_threads_on(outputStream* st) const {
80 assert(workers() != NULL, "should have workers here");
81 workers()->print_worker_threads_on(st);
82 ConcurrentMarkSweepThread::print_all_on(st);
83 }
84
85 void CMSHeap::print_on_error(outputStream* st) const {
86 this->GenCollectedHeap::print_on_error(st);
87 st->cr();
88 CMSCollector::print_on_error(st);
89 }
90
91 bool CMSHeap::create_cms_collector() {
92
93 assert(old_gen()->kind() == Generation::ConcurrentMarkSweep,
94 "Unexpected generation kinds");
95 // Skip two header words in the block content verification
96 NOT_PRODUCT(_skip_header_HeapWords = CMSCollector::skip_header_HeapWords();)
97 assert(gen_policy()->is_concurrent_mark_sweep_policy(), "Unexpected policy type");
98 CMSCollector* collector =
99 new CMSCollector((ConcurrentMarkSweepGeneration*) old_gen(),
100 rem_set(),
101 gen_policy()->as_concurrent_mark_sweep_policy());
102
103 if (collector == NULL || !collector->completed_initialization()) {
104 if (collector) {
105 delete collector; // Be nice in embedded situation
106 }
107 vm_shutdown_during_initialization("Could not create CMS collector");
108 return false;
109 }
110 return true; // success
111 }
112
113 void CMSHeap::collect(GCCause::Cause cause) {
114 if (should_do_concurrent_full_gc(cause)) {
115 // Mostly concurrent full collection.
116 collect_mostly_concurrent(cause);
117 } else {
118 GenCollectedHeap::collect(cause);
119 }
120 }
121
122 bool CMSHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
123 if (!UseConcMarkSweepGC) {
124 return false;
125 }
126
127 switch (cause) {
128 case GCCause::_gc_locker: return GCLockerInvokesConcurrent;
129 case GCCause::_java_lang_system_gc:
130 case GCCause::_dcmd_gc_run: return ExplicitGCInvokesConcurrent;
131 default: return false;
132 }
133 }
134
135
136 void CMSHeap::collect_mostly_concurrent(GCCause::Cause cause) {
137 assert(!Heap_lock->owned_by_self(), "Should not own Heap_lock");
138
139 MutexLocker ml(Heap_lock);
140 // Read the GC counts while holding the Heap_lock
141 unsigned int full_gc_count_before = total_full_collections();
142 unsigned int gc_count_before = total_collections();
143 {
144 MutexUnlocker mu(Heap_lock);
145 VM_GenCollectFullConcurrent op(gc_count_before, full_gc_count_before, cause);
146 VMThread::execute(&op);
147 }
148 }
149
150 void CMSHeap::stop() {
151 ConcurrentMarkSweepThread::cmst()->stop();
152 }
153
154 void CMSHeap::cms_process_roots(StrongRootsScope* scope,
155 bool young_gen_as_roots,
156 ScanningOption so,
157 bool only_strong_roots,
158 OopsInGenClosure* root_closure,
159 CLDClosure* cld_closure) {
160 MarkingCodeBlobClosure mark_code_closure(root_closure, !CodeBlobToOopClosure::FixRelocations);
161 OopsInGenClosure* weak_roots = only_strong_roots ? NULL : root_closure;
162 CLDClosure* weak_cld_closure = only_strong_roots ? NULL : cld_closure;
163
164 process_roots(scope, so, root_closure, weak_roots, cld_closure, weak_cld_closure, &mark_code_closure);
165 if (!only_strong_roots) {
166 process_string_table_roots(scope, root_closure);
167 }
168
169 if (young_gen_as_roots &&
170 !_process_strong_tasks->is_task_claimed(GCH_PS_younger_gens)) {
171 root_closure->set_generation(young_gen());
172 young_gen()->oop_iterate(root_closure);
173 root_closure->reset_generation();
174 }
175
176 _process_strong_tasks->all_tasks_completed(scope->n_threads());
177 }
178