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 && (CMSParallelInitialMarkEnabled ||
69 CMSParallelRemarkEnabled)) ||
70 UseG1GC) &&
71 ParallelGCThreads > 0) {
72 _workers = new FlexibleWorkGang("Parallel GC Threads", ParallelGCThreads,
73 /* are_GC_task_threads */true,
74 /* are_ConcurrentGC_threads */false);
75 if (_workers == NULL) {
76 vm_exit_during_initialization("Failed necessary allocation.");
77 } else {
78 _workers->initialize_workers();
79 }
80 }
81 }
82
83 int SharedHeap::n_termination() {
84 return _process_strong_tasks->n_threads();
85 }
86
87 void SharedHeap::set_n_termination(int t) {
88 _process_strong_tasks->set_n_threads(t);
89 }
90
91 bool SharedHeap::heap_lock_held_for_gc() {
92 Thread* t = Thread::current();
93 return Heap_lock->owned_by_self()
94 || ( (t->is_GC_task_thread() || t->is_VM_thread())
95 && _thread_holds_heap_lock_for_gc);
96 }
97
98 void SharedHeap::set_par_threads(uint t) {
99 assert(t == 0 || !UseSerialGC, "Cannot have parallel threads");
100 _n_par_threads = t;
101 _process_strong_tasks->set_n_threads(t);
102 }
103
104 #ifdef ASSERT
105 class AssertNonScavengableClosure: public OopClosure {
106 public:
107 virtual void do_oop(oop* p) {
108 assert(!Universe::heap()->is_in_partial_collection(*p),
109 "Referent should not be scavengable."); }
110 virtual void do_oop(narrowOop* p) { ShouldNotReachHere(); }
111 };
112 static AssertNonScavengableClosure assert_is_non_scavengable_closure;
113 #endif
114
115 void SharedHeap::change_strong_roots_parity() {
116 // Also set the new collection parity.
117 assert(_strong_roots_parity >= 0 && _strong_roots_parity <= 2,
118 "Not in range.");
119 _strong_roots_parity++;
120 if (_strong_roots_parity == 3) _strong_roots_parity = 1;
121 assert(_strong_roots_parity >= 1 && _strong_roots_parity <= 2,
122 "Not in range.");
123 }
124
125 SharedHeap::StrongRootsScope::StrongRootsScope(SharedHeap* outer, bool activate)
126 : MarkScope(activate)
127 {
128 if (_active) {
129 outer->change_strong_roots_parity();
130 // Zero the claimed high water mark in the StringTable
131 StringTable::clear_parallel_claimed_index();
132 }
133 }
134
135 SharedHeap::StrongRootsScope::~StrongRootsScope() {
136 // nothing particular
137 }
138
139 void SharedHeap::process_strong_roots(bool activate_scope,
140 bool is_scavenging,
141 ScanningOption so,
142 OopClosure* roots,
143 CodeBlobClosure* code_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 // All threads execute this; the individual threads are task groups.
161 CLDToOopClosure roots_from_clds(roots);
162 CLDToOopClosure* roots_from_clds_p = (is_scavenging ? NULL : &roots_from_clds);
163 if (CollectedHeap::use_parallel_gc_threads()) {
164 Threads::possibly_parallel_oops_do(roots, roots_from_clds_p, code_roots);
165 } else {
166 Threads::oops_do(roots, roots_from_clds_p, code_roots);
167 }
168
169 if (!_process_strong_tasks-> is_task_claimed(SH_PS_ObjectSynchronizer_oops_do))
170 ObjectSynchronizer::oops_do(roots);
171 if (!_process_strong_tasks->is_task_claimed(SH_PS_FlatProfiler_oops_do))
172 FlatProfiler::oops_do(roots);
173 if (!_process_strong_tasks->is_task_claimed(SH_PS_Management_oops_do))
174 Management::oops_do(roots);
175 if (!_process_strong_tasks->is_task_claimed(SH_PS_jvmti_oops_do))
176 JvmtiExport::oops_do(roots);
177
178 if (!_process_strong_tasks->is_task_claimed(SH_PS_SystemDictionary_oops_do)) {
179 if (so & SO_AllClasses) {
180 SystemDictionary::oops_do(roots);
181 } else if (so & SO_SystemClasses) {
182 SystemDictionary::always_strong_oops_do(roots);
183 } else {
184 fatal("We should always have selected either SO_AllClasses or SO_SystemClasses");
185 }
186 }
187
188 if (!_process_strong_tasks->is_task_claimed(SH_PS_ClassLoaderDataGraph_oops_do)) {
189 if (so & SO_AllClasses) {
190 ClassLoaderDataGraph::oops_do(roots, klass_closure, !is_scavenging);
191 } else if (so & SO_SystemClasses) {
192 ClassLoaderDataGraph::always_strong_oops_do(roots, klass_closure, !is_scavenging);
193 }
194 }
195
196 // All threads execute the following. A specific chunk of buckets
197 // from the StringTable are the individual tasks.
198 if (so & SO_Strings) {
199 if (CollectedHeap::use_parallel_gc_threads()) {
200 StringTable::possibly_parallel_oops_do(roots);
201 } else {
202 StringTable::oops_do(roots);
203 }
204 }
205
206 if (!_process_strong_tasks->is_task_claimed(SH_PS_CodeCache_oops_do)) {
207 if (so & SO_CodeCache) {
208 assert(code_roots != NULL, "must supply closure for code cache");
209
210 if (is_scavenging) {
211 // We only visit parts of the CodeCache when scavenging.
212 CodeCache::scavenge_root_nmethods_do(code_roots);
213 } else {
214 // CMSCollector uses this to do intermediate-strength collections.
215 // We scan the entire code cache, since CodeCache::do_unloading is not called.
216 CodeCache::blobs_do(code_roots);
217 }
218 }
219 // Verify that the code cache contents are not subject to
220 // movement by a scavenging collection.
221 DEBUG_ONLY(CodeBlobToOopClosure assert_code_is_non_scavengable(&assert_is_non_scavengable_closure, /*do_marking=*/ false));
222 DEBUG_ONLY(CodeCache::asserted_non_scavengable_nmethods_do(&assert_code_is_non_scavengable));
223 }
224
225 _process_strong_tasks->all_tasks_completed();
226 }
227
228 class AlwaysTrueClosure: public BoolObjectClosure {
229 public:
230 bool do_object_b(oop p) { return true; }
231 };
232 static AlwaysTrueClosure always_true;
233
234 void SharedHeap::process_weak_roots(OopClosure* root_closure,
235 CodeBlobClosure* code_roots) {
236 // Global (weak) JNI handles
237 JNIHandles::weak_oops_do(&always_true, root_closure);
238
239 CodeCache::blobs_do(code_roots);
240 StringTable::oops_do(root_closure);
241 }
242
243 void SharedHeap::set_barrier_set(BarrierSet* bs) {
244 _barrier_set = bs;
245 // Cached barrier set for fast access in oops
246 oopDesc::set_bs(bs);
247 }
248
249 void SharedHeap::post_initialize() {
250 ref_processing_init();
251 }
252
253 void SharedHeap::ref_processing_init() {}
254
255 // Some utilities.
256 void SharedHeap::print_size_transition(outputStream* out,
257 size_t bytes_before,
258 size_t bytes_after,
259 size_t capacity) {
260 out->print(" %d%s->%d%s(%d%s)",
261 byte_size_in_proper_unit(bytes_before),
262 proper_unit_for_byte_size(bytes_before),
263 byte_size_in_proper_unit(bytes_after),
264 proper_unit_for_byte_size(bytes_after),
265 byte_size_in_proper_unit(capacity),
266 proper_unit_for_byte_size(capacity));
267 }