1 /*
2 * Copyright (c) 2000, 2014, 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 "classfile/stringTable.hpp"
27 #include "classfile/systemDictionary.hpp"
28 #include "code/codeCache.hpp"
29 #include "gc_interface/collectedHeap.inline.hpp"
30 #include "memory/sharedHeap.hpp"
31 #include "oops/oop.inline.hpp"
32 #include "runtime/fprofiler.hpp"
33 #include "runtime/java.hpp"
34 #include "services/management.hpp"
35 #include "utilities/copy.hpp"
36 #include "utilities/workgroup.hpp"
37
38 PRAGMA_FORMAT_MUTE_WARNINGS_FOR_GCC
39
40 SharedHeap* SharedHeap::_sh;
41
42 // The set of potentially parallel tasks in strong root scanning.
43 enum SH_process_strong_roots_tasks {
44 SH_PS_Universe_oops_do,
45 SH_PS_JNIHandles_oops_do,
46 SH_PS_ObjectSynchronizer_oops_do,
47 SH_PS_FlatProfiler_oops_do,
48 SH_PS_Management_oops_do,
49 SH_PS_SystemDictionary_oops_do,
50 SH_PS_ClassLoaderDataGraph_oops_do,
51 SH_PS_jvmti_oops_do,
52 SH_PS_CodeCache_oops_do,
53 // Leave this one last.
54 SH_PS_NumElements
55 };
56
57 SharedHeap::SharedHeap(CollectorPolicy* policy_) :
58 CollectedHeap(),
59 _collector_policy(policy_),
60 _rem_set(NULL),
61 _strong_roots_parity(0),
62 _process_strong_tasks(new SubTasksDone(SH_PS_NumElements)),
63 _workers(NULL)
64 {
65 if (_process_strong_tasks == NULL || !_process_strong_tasks->valid()) {
66 vm_exit_during_initialization("Failed necessary allocation.");
67 }
68 _sh = this; // ch is static, should be set only once.
69 if ((UseParNewGC ||
70 (UseConcMarkSweepGC && (CMSParallelInitialMarkEnabled ||
71 CMSParallelRemarkEnabled)) ||
72 UseG1GC) &&
73 ParallelGCThreads > 0) {
74 _workers = new FlexibleWorkGang("Parallel GC Threads", ParallelGCThreads,
75 /* are_GC_task_threads */true,
76 /* are_ConcurrentGC_threads */false);
77 if (_workers == NULL) {
78 vm_exit_during_initialization("Failed necessary allocation.");
79 } else {
80 _workers->initialize_workers();
81 }
82 }
83 }
84
85 int SharedHeap::n_termination() {
86 return _process_strong_tasks->n_threads();
87 }
88
89 void SharedHeap::set_n_termination(int t) {
90 _process_strong_tasks->set_n_threads(t);
91 }
92
93 bool SharedHeap::heap_lock_held_for_gc() {
94 Thread* t = Thread::current();
95 return Heap_lock->owned_by_self()
96 || ( (t->is_GC_task_thread() || t->is_VM_thread())
97 && _thread_holds_heap_lock_for_gc);
98 }
99
100 void SharedHeap::set_par_threads(uint t) {
101 assert(t == 0 || !UseSerialGC, "Cannot have parallel threads");
102 _n_par_threads = t;
103 _process_strong_tasks->set_n_threads(t);
104 }
105
106 #ifdef ASSERT
107 class AssertNonScavengableClosure: public OopClosure {
108 public:
109 virtual void do_oop(oop* p) {
110 assert(!Universe::heap()->is_in_partial_collection(*p),
111 "Referent should not be scavengable."); }
112 virtual void do_oop(narrowOop* p) { ShouldNotReachHere(); }
113 };
114 static AssertNonScavengableClosure assert_is_non_scavengable_closure;
115 #endif
116
117 void SharedHeap::change_strong_roots_parity() {
118 // Also set the new collection parity.
119 assert(_strong_roots_parity >= 0 && _strong_roots_parity <= 2,
120 "Not in range.");
121 _strong_roots_parity++;
122 if (_strong_roots_parity == 3) _strong_roots_parity = 1;
123 assert(_strong_roots_parity >= 1 && _strong_roots_parity <= 2,
124 "Not in range.");
125 }
126
127 SharedHeap::StrongRootsScope::StrongRootsScope(SharedHeap* outer, bool activate)
128 : MarkScope(activate)
129 {
130 if (_active) {
131 outer->change_strong_roots_parity();
132 // Zero the claimed high water mark in the StringTable
133 StringTable::clear_parallel_claimed_index();
134 }
135 }
136
137 SharedHeap::StrongRootsScope::~StrongRootsScope() {
138 // nothing particular
139 }
140
141 void SharedHeap::process_strong_roots(bool activate_scope,
142 ScanningOption so,
143 OopClosure* roots,
144 KlassClosure* klass_closure) {
145 StrongRootsScope srs(this, activate_scope);
146
147 // General strong roots.
148 assert(_strong_roots_parity != 0, "must have called prologue code");
149 // _n_termination for _process_strong_tasks should be set up stream
150 // in a method not running in a GC worker. Otherwise the GC worker
151 // could be trying to change the termination condition while the task
152 // is executing in another GC worker.
153 if (!_process_strong_tasks->is_task_claimed(SH_PS_Universe_oops_do)) {
154 Universe::oops_do(roots);
155 }
156 // Global (strong) JNI handles
157 if (!_process_strong_tasks->is_task_claimed(SH_PS_JNIHandles_oops_do))
158 JNIHandles::oops_do(roots);
159
160 CodeBlobToOopClosure code_roots(roots, true);
161
162 CLDToOopClosure roots_from_clds(roots);
163 // If we limit class scanning to SO_SystemClasses we need to apply a CLD closure to
164 // CLDs which are strongly reachable from the thread stacks.
165 CLDToOopClosure* roots_from_clds_p = ((so & SO_SystemClasses) ? &roots_from_clds : NULL);
166 // All threads execute this; the individual threads are task groups.
167 if (CollectedHeap::use_parallel_gc_threads()) {
168 Threads::possibly_parallel_oops_do(roots, roots_from_clds_p, &code_roots);
169 } else {
170 Threads::oops_do(roots, roots_from_clds_p, &code_roots);
171 }
172
173 if (!_process_strong_tasks-> is_task_claimed(SH_PS_ObjectSynchronizer_oops_do))
174 ObjectSynchronizer::oops_do(roots);
175 if (!_process_strong_tasks->is_task_claimed(SH_PS_FlatProfiler_oops_do))
176 FlatProfiler::oops_do(roots);
177 if (!_process_strong_tasks->is_task_claimed(SH_PS_Management_oops_do))
178 Management::oops_do(roots);
179 if (!_process_strong_tasks->is_task_claimed(SH_PS_jvmti_oops_do))
180 JvmtiExport::oops_do(roots);
181
182 if (!_process_strong_tasks->is_task_claimed(SH_PS_SystemDictionary_oops_do)) {
183 if (so & SO_AllClasses) {
184 SystemDictionary::oops_do(roots);
185 } else if (so & SO_SystemClasses) {
186 SystemDictionary::always_strong_oops_do(roots);
187 } else {
188 fatal("We should always have selected either SO_AllClasses or SO_SystemClasses");
189 }
190 }
191
192 if (!_process_strong_tasks->is_task_claimed(SH_PS_ClassLoaderDataGraph_oops_do)) {
193 if (so & SO_AllClasses) {
194 ClassLoaderDataGraph::oops_do(roots, klass_closure, /* must_claim */ false);
195 } else if (so & SO_SystemClasses) {
196 ClassLoaderDataGraph::always_strong_oops_do(roots, klass_closure, /* must_claim */ true);
197 }
198 }
199
200 // All threads execute the following. A specific chunk of buckets
201 // from the StringTable are the individual tasks.
202 if (so & SO_Strings) {
203 if (CollectedHeap::use_parallel_gc_threads()) {
204 StringTable::possibly_parallel_oops_do(roots);
205 } else {
206 StringTable::oops_do(roots);
207 }
208 }
209
210 if (!_process_strong_tasks->is_task_claimed(SH_PS_CodeCache_oops_do)) {
211 if (so & SO_ScavengeCodeCache) {
212 assert(&code_roots != NULL, "must supply closure for code cache");
213
214 // We only visit parts of the CodeCache when scavenging.
215 CodeCache::scavenge_root_nmethods_do(&code_roots);
216 }
217 if (so & SO_AllCodeCache) {
218 assert(&code_roots != NULL, "must supply closure for code cache");
219
220 // CMSCollector uses this to do intermediate-strength collections.
221 // We scan the entire code cache, since CodeCache::do_unloading is not called.
222 CodeCache::blobs_do(&code_roots);
223 }
224 // Verify that the code cache contents are not subject to
225 // movement by a scavenging collection.
226 DEBUG_ONLY(CodeBlobToOopClosure assert_code_is_non_scavengable(&assert_is_non_scavengable_closure, /*do_marking=*/ false));
227 DEBUG_ONLY(CodeCache::asserted_non_scavengable_nmethods_do(&assert_code_is_non_scavengable));
228 }
229
230 _process_strong_tasks->all_tasks_completed();
231 }
232
233 class AlwaysTrueClosure: public BoolObjectClosure {
234 public:
235 bool do_object_b(oop p) { return true; }
236 };
237 static AlwaysTrueClosure always_true;
238
239 void SharedHeap::process_weak_roots(OopClosure* root_closure) {
240 // Global (weak) JNI handles
241 JNIHandles::weak_oops_do(&always_true, root_closure);
242 }
243
244 void SharedHeap::set_barrier_set(BarrierSet* bs) {
245 _barrier_set = bs;
246 // Cached barrier set for fast access in oops
247 oopDesc::set_bs(bs);
248 }
249
250 void SharedHeap::post_initialize() {
251 CollectedHeap::post_initialize();
252 ref_processing_init();
253 }
254
255 void SharedHeap::ref_processing_init() {}
256
257 // Some utilities.
258 void SharedHeap::print_size_transition(outputStream* out,
259 size_t bytes_before,
260 size_t bytes_after,
261 size_t capacity) {
262 out->print(" " SIZE_FORMAT "%s->" SIZE_FORMAT "%s(" SIZE_FORMAT "%s)",
263 byte_size_in_proper_unit(bytes_before),
264 proper_unit_for_byte_size(bytes_before),
265 byte_size_in_proper_unit(bytes_after),
266 proper_unit_for_byte_size(bytes_after),
267 byte_size_in_proper_unit(capacity),
268 proper_unit_for_byte_size(capacity));
269 }