1 /*
2 * Copyright (c) 2000, 2013, 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/symbolTable.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 SharedHeap* SharedHeap::_sh;
39
40 // The set of potentially parallel tasks in strong root scanning.
41 enum SH_process_strong_roots_tasks {
42 SH_PS_Universe_oops_do,
43 SH_PS_JNIHandles_oops_do,
44 SH_PS_ObjectSynchronizer_oops_do,
45 SH_PS_FlatProfiler_oops_do,
46 SH_PS_Management_oops_do,
47 SH_PS_SystemDictionary_oops_do,
48 SH_PS_ClassLoaderDataGraph_oops_do,
49 SH_PS_jvmti_oops_do,
50 SH_PS_CodeCache_oops_do,
51 // Leave this one last.
52 SH_PS_NumElements
53 };
54
55 SharedHeap::SharedHeap(CollectorPolicy* policy_) :
56 CollectedHeap(),
57 _collector_policy(policy_),
58 _rem_set(NULL),
59 _strong_roots_parity(0),
60 _process_strong_tasks(new SubTasksDone(SH_PS_NumElements)),
61 _workers(NULL)
62 {
63 if (_process_strong_tasks == NULL || !_process_strong_tasks->valid()) {
64 vm_exit_during_initialization("Failed necessary allocation.");
65 }
66 _sh = this; // ch is static, should be set only once.
67 if ((UseParNewGC ||
68 (UseConcMarkSweepGC && CMSParallelRemarkEnabled) ||
69 UseG1GC) &&
70 ParallelGCThreads > 0) {
71 _workers = new FlexibleWorkGang("Parallel GC Threads", ParallelGCThreads,
72 /* are_GC_task_threads */true,
73 /* are_ConcurrentGC_threads */false);
74 if (_workers == NULL) {
75 vm_exit_during_initialization("Failed necessary allocation.");
76 } else {
77 _workers->initialize_workers();
78 }
79 }
80 }
81
82 int SharedHeap::n_termination() {
83 return _process_strong_tasks->n_threads();
84 }
85
86 void SharedHeap::set_n_termination(int t) {
87 _process_strong_tasks->set_n_threads(t);
88 }
89
90 bool SharedHeap::heap_lock_held_for_gc() {
91 Thread* t = Thread::current();
92 return Heap_lock->owned_by_self()
93 || ( (t->is_GC_task_thread() || t->is_VM_thread())
94 && _thread_holds_heap_lock_for_gc);
95 }
96
97 void SharedHeap::set_par_threads(uint t) {
98 assert(t == 0 || !UseSerialGC, "Cannot have parallel threads");
99 _n_par_threads = t;
100 _process_strong_tasks->set_n_threads(t);
101 }
102
103 #ifdef ASSERT
104 class AssertNonScavengableClosure: public OopClosure {
105 public:
106 virtual void do_oop(oop* p) {
107 assert(!Universe::heap()->is_in_partial_collection(*p),
108 "Referent should not be scavengable."); }
109 virtual void do_oop(narrowOop* p) { ShouldNotReachHere(); }
110 };
111 static AssertNonScavengableClosure assert_is_non_scavengable_closure;
112 #endif
113
114 void SharedHeap::change_strong_roots_parity() {
115 // Also set the new collection parity.
116 assert(_strong_roots_parity >= 0 && _strong_roots_parity <= 2,
117 "Not in range.");
118 _strong_roots_parity++;
119 if (_strong_roots_parity == 3) _strong_roots_parity = 1;
120 assert(_strong_roots_parity >= 1 && _strong_roots_parity <= 2,
121 "Not in range.");
122 }
123
124 SharedHeap::StrongRootsScope::StrongRootsScope(SharedHeap* outer, bool activate)
125 : MarkScope(activate)
126 {
127 if (_active) {
128 outer->change_strong_roots_parity();
129 // Zero the claimed high water mark in the StringTable
130 StringTable::clear_parallel_claimed_index();
131 }
132 }
133
134 SharedHeap::StrongRootsScope::~StrongRootsScope() {
135 // nothing particular
136 }
137
138 void SharedHeap::process_strong_roots(bool activate_scope,
139 bool is_scavenging,
140 ScanningOption so,
141 OopClosure* roots,
142 CodeBlobClosure* code_roots,
143 KlassClosure* klass_closure) {
144 StrongRootsScope srs(this, activate_scope);
145
146 // General strong roots.
147 assert(_strong_roots_parity != 0, "must have called prologue code");
148 // _n_termination for _process_strong_tasks should be set up stream
149 // in a method not running in a GC worker. Otherwise the GC worker
150 // could be trying to change the termination condition while the task
151 // is executing in another GC worker.
152 if (!_process_strong_tasks->is_task_claimed(SH_PS_Universe_oops_do)) {
153 Universe::oops_do(roots);
154 }
155 // Global (strong) JNI handles
156 if (!_process_strong_tasks->is_task_claimed(SH_PS_JNIHandles_oops_do))
157 JNIHandles::oops_do(roots);
158
159 // All threads execute this; the individual threads are task groups.
160 CLDToOopClosure roots_from_clds(roots);
161 CLDToOopClosure* roots_from_clds_p = (is_scavenging ? NULL : &roots_from_clds);
162 if (CollectedHeap::use_parallel_gc_threads()) {
163 Threads::possibly_parallel_oops_do(roots, roots_from_clds_p, code_roots);
164 } else {
165 Threads::oops_do(roots, roots_from_clds_p, code_roots);
166 }
167
168 if (!_process_strong_tasks-> is_task_claimed(SH_PS_ObjectSynchronizer_oops_do))
169 ObjectSynchronizer::oops_do(roots);
170 if (!_process_strong_tasks->is_task_claimed(SH_PS_FlatProfiler_oops_do))
171 FlatProfiler::oops_do(roots);
172 if (!_process_strong_tasks->is_task_claimed(SH_PS_Management_oops_do))
173 Management::oops_do(roots);
174 if (!_process_strong_tasks->is_task_claimed(SH_PS_jvmti_oops_do))
175 JvmtiExport::oops_do(roots);
176
177 if (!_process_strong_tasks->is_task_claimed(SH_PS_SystemDictionary_oops_do)) {
178 if (so & SO_AllClasses) {
179 SystemDictionary::oops_do(roots);
180 } else if (so & SO_SystemClasses) {
181 SystemDictionary::always_strong_oops_do(roots);
182 } else {
183 fatal("We should always have selected either SO_AllClasses or SO_SystemClasses");
184 }
185 }
186
187 if (!_process_strong_tasks->is_task_claimed(SH_PS_ClassLoaderDataGraph_oops_do)) {
188 if (so & SO_AllClasses) {
189 ClassLoaderDataGraph::oops_do(roots, klass_closure, !is_scavenging);
190 } else if (so & SO_SystemClasses) {
191 ClassLoaderDataGraph::always_strong_oops_do(roots, klass_closure, !is_scavenging);
192 }
193 }
194
195 // All threads execute the following. A specific chunk of buckets
196 // from the StringTable are the individual tasks.
197 if (so & SO_Strings) {
198 if (CollectedHeap::use_parallel_gc_threads()) {
199 StringTable::possibly_parallel_oops_do(roots);
200 } else {
201 StringTable::oops_do(roots);
202 }
203 }
204
205 if (!_process_strong_tasks->is_task_claimed(SH_PS_CodeCache_oops_do)) {
206 if (so & SO_CodeCache) {
207 assert(code_roots != NULL, "must supply closure for code cache");
208
209 if (is_scavenging) {
210 // We only visit parts of the CodeCache when scavenging.
211 CodeCache::scavenge_root_nmethods_do(code_roots);
212 } else {
213 // CMSCollector uses this to do intermediate-strength collections.
214 // We scan the entire code cache, since CodeCache::do_unloading is not called.
215 CodeCache::blobs_do(code_roots);
216 }
217 }
218 // Verify that the code cache contents are not subject to
219 // movement by a scavenging collection.
220 DEBUG_ONLY(CodeBlobToOopClosure assert_code_is_non_scavengable(&assert_is_non_scavengable_closure, /*do_marking=*/ false));
221 DEBUG_ONLY(CodeCache::asserted_non_scavengable_nmethods_do(&assert_code_is_non_scavengable));
222 }
223
224 _process_strong_tasks->all_tasks_completed();
225 }
226
227 class AlwaysTrueClosure: public BoolObjectClosure {
228 public:
229 bool do_object_b(oop p) { return true; }
230 };
231 static AlwaysTrueClosure always_true;
232
233 void SharedHeap::process_weak_roots(OopClosure* root_closure,
234 CodeBlobClosure* code_roots) {
235 // Global (weak) JNI handles
236 JNIHandles::weak_oops_do(&always_true, root_closure);
237
238 CodeCache::blobs_do(code_roots);
239 StringTable::oops_do(root_closure);
240 }
241
242 void SharedHeap::set_barrier_set(BarrierSet* bs) {
243 _barrier_set = bs;
244 // Cached barrier set for fast access in oops
245 oopDesc::set_bs(bs);
246 }
247
248 void SharedHeap::post_initialize() {
249 ref_processing_init();
250 }
251
252 void SharedHeap::ref_processing_init() {}
253
254 // Some utilities.
255 void SharedHeap::print_size_transition(outputStream* out,
256 size_t bytes_before,
257 size_t bytes_after,
258 size_t capacity) {
259 out->print(" %d%s->%d%s(%d%s)",
260 byte_size_in_proper_unit(bytes_before),
261 proper_unit_for_byte_size(bytes_before),
262 byte_size_in_proper_unit(bytes_after),
263 proper_unit_for_byte_size(bytes_after),
264 byte_size_in_proper_unit(capacity),
265 proper_unit_for_byte_size(capacity));
266 }