1 /*
2 * Copyright (c) 2000, 2011, 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_jvmti_oops_do,
49 SH_PS_StringTable_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 _perm_gen(NULL), _rem_set(NULL),
59 _strong_roots_parity(0),
60 _process_strong_tasks(new SubTasksDone(SH_PS_NumElements)),
61 _n_par_threads(0),
62 _workers(NULL)
63 {
64 if (_process_strong_tasks == NULL || !_process_strong_tasks->valid()) {
65 vm_exit_during_initialization("Failed necessary allocation.");
66 }
67 _sh = this; // ch is static, should be set only once.
68 if ((UseParNewGC ||
69 (UseConcMarkSweepGC && 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 bool SharedHeap::heap_lock_held_for_gc() {
84 Thread* t = Thread::current();
85 return Heap_lock->owned_by_self()
86 || ( (t->is_GC_task_thread() || t->is_VM_thread())
87 && _thread_holds_heap_lock_for_gc);
88 }
89
90 void SharedHeap::set_par_threads(int t) {
91 assert(t == 0 || !UseSerialGC, "Cannot have parallel threads");
92 _n_par_threads = t;
93 _process_strong_tasks->set_n_threads(t);
94 }
95
96 class AssertIsPermClosure: public OopClosure {
97 public:
98 virtual void do_oop(oop* p) {
99 assert((*p) == NULL || (*p)->is_perm(), "Referent should be perm.");
100 }
101 virtual void do_oop(narrowOop* p) { ShouldNotReachHere(); }
102 };
103 static AssertIsPermClosure assert_is_perm_closure;
104
105 #ifdef ASSERT
106 class AssertNonScavengableClosure: public OopClosure {
107 public:
108 virtual void do_oop(oop* p) {
109 assert(!Universe::heap()->is_in_partial_collection(*p),
110 "Referent should not be scavengable."); }
111 virtual void do_oop(narrowOop* p) { ShouldNotReachHere(); }
112 };
113 static AssertNonScavengableClosure assert_is_non_scavengable_closure;
114 #endif
115
116 void SharedHeap::change_strong_roots_parity() {
117 // Also set the new collection parity.
118 assert(_strong_roots_parity >= 0 && _strong_roots_parity <= 2,
119 "Not in range.");
120 _strong_roots_parity++;
121 if (_strong_roots_parity == 3) _strong_roots_parity = 1;
122 assert(_strong_roots_parity >= 1 && _strong_roots_parity <= 2,
123 "Not in range.");
124 }
125
126 SharedHeap::StrongRootsScope::StrongRootsScope(SharedHeap* outer, bool activate)
127 : MarkScope(activate)
128 {
129 if (_active) {
130 outer->change_strong_roots_parity();
131 }
132 }
133
134 SharedHeap::StrongRootsScope::~StrongRootsScope() {
135 // nothing particular
136 }
137
138 void SharedHeap::process_strong_roots(bool activate_scope,
139 bool collecting_perm_gen,
140 ScanningOption so,
141 OopClosure* roots,
142 CodeBlobClosure* code_roots,
143 OopsInGenClosure* perm_blk) {
144 StrongRootsScope srs(this, activate_scope);
145 // General strong roots.
146 assert(_strong_roots_parity != 0, "must have called prologue code");
147 if (!_process_strong_tasks->is_task_claimed(SH_PS_Universe_oops_do)) {
148 Universe::oops_do(roots);
149 // Consider perm-gen discovered lists to be strong.
150 perm_gen()->ref_processor()->weak_oops_do(roots);
151 }
152 // Global (strong) JNI handles
153 if (!_process_strong_tasks->is_task_claimed(SH_PS_JNIHandles_oops_do))
154 JNIHandles::oops_do(roots);
155 // All threads execute this; the individual threads are task groups.
156 if (ParallelGCThreads > 0) {
157 Threads::possibly_parallel_oops_do(roots, code_roots);
158 } else {
159 Threads::oops_do(roots, code_roots);
160 }
161 if (!_process_strong_tasks-> is_task_claimed(SH_PS_ObjectSynchronizer_oops_do))
162 ObjectSynchronizer::oops_do(roots);
163 if (!_process_strong_tasks->is_task_claimed(SH_PS_FlatProfiler_oops_do))
164 FlatProfiler::oops_do(roots);
165 if (!_process_strong_tasks->is_task_claimed(SH_PS_Management_oops_do))
166 Management::oops_do(roots);
167 if (!_process_strong_tasks->is_task_claimed(SH_PS_jvmti_oops_do))
168 JvmtiExport::oops_do(roots);
169
170 if (!_process_strong_tasks->is_task_claimed(SH_PS_SystemDictionary_oops_do)) {
171 if (so & SO_AllClasses) {
172 SystemDictionary::oops_do(roots);
173 } else if (so & SO_SystemClasses) {
174 SystemDictionary::always_strong_oops_do(roots);
175 }
176 }
177
178 if (!_process_strong_tasks->is_task_claimed(SH_PS_StringTable_oops_do)) {
179 if (so & SO_Strings || (!collecting_perm_gen && !JavaObjectsInPerm)) {
180 StringTable::oops_do(roots);
181 }
182 if (JavaObjectsInPerm) {
183 // Verify the string table contents are in the perm gen
184 NOT_PRODUCT(StringTable::oops_do(&assert_is_perm_closure));
185 }
186 }
187
188 if (!_process_strong_tasks->is_task_claimed(SH_PS_CodeCache_oops_do)) {
189 if (so & SO_CodeCache) {
190 // (Currently, CMSCollector uses this to do intermediate-strength collections.)
191 assert(collecting_perm_gen, "scanning all of code cache");
192 assert(code_roots != NULL, "must supply closure for code cache");
193 if (code_roots != NULL) {
194 CodeCache::blobs_do(code_roots);
195 }
196 } else if (so & (SO_SystemClasses|SO_AllClasses)) {
197 if (!collecting_perm_gen) {
198 // If we are collecting from class statics, but we are not going to
199 // visit all of the CodeCache, collect from the non-perm roots if any.
200 // This makes the code cache function temporarily as a source of strong
201 // roots for oops, until the next major collection.
202 //
203 // If collecting_perm_gen is true, we require that this phase will call
204 // CodeCache::do_unloading. This will kill off nmethods with expired
205 // weak references, such as stale invokedynamic targets.
206 CodeCache::scavenge_root_nmethods_do(code_roots);
207 }
208 }
209 // Verify that the code cache contents are not subject to
210 // movement by a scavenging collection.
211 DEBUG_ONLY(CodeBlobToOopClosure assert_code_is_non_scavengable(&assert_is_non_scavengable_closure, /*do_marking=*/ false));
212 DEBUG_ONLY(CodeCache::asserted_non_scavengable_nmethods_do(&assert_code_is_non_scavengable));
213 }
214
215 if (!collecting_perm_gen) {
216 // All threads perform this; coordination is handled internally.
217
218 rem_set()->younger_refs_iterate(perm_gen(), perm_blk);
219 }
220 _process_strong_tasks->all_tasks_completed();
221 }
222
223 class AlwaysTrueClosure: public BoolObjectClosure {
224 public:
225 void do_object(oop p) { ShouldNotReachHere(); }
226 bool do_object_b(oop p) { return true; }
227 };
228 static AlwaysTrueClosure always_true;
229
230 class SkipAdjustingSharedStrings: public OopClosure {
231 OopClosure* _clo;
232 public:
233 SkipAdjustingSharedStrings(OopClosure* clo) : _clo(clo) {}
234
235 virtual void do_oop(oop* p) {
236 oop o = (*p);
237 if (!o->is_shared_readwrite()) {
238 _clo->do_oop(p);
239 }
240 }
241 virtual void do_oop(narrowOop* p) { ShouldNotReachHere(); }
242 };
243
244 // Unmarked shared Strings in the StringTable (which got there due to
245 // being in the constant pools of as-yet unloaded shared classes) were
246 // not marked and therefore did not have their mark words preserved.
247 // These entries are also deliberately not purged from the string
248 // table during unloading of unmarked strings. If an identity hash
249 // code was computed for any of these objects, it will not have been
250 // cleared to zero during the forwarding process or by the
251 // RecursiveAdjustSharedObjectClosure, and will be confused by the
252 // adjusting process as a forwarding pointer. We need to skip
253 // forwarding StringTable entries which contain unmarked shared
254 // Strings. Actually, since shared strings won't be moving, we can
255 // just skip adjusting any shared entries in the string table.
256
257 void SharedHeap::process_weak_roots(OopClosure* root_closure,
258 CodeBlobClosure* code_roots,
259 OopClosure* non_root_closure) {
260 // Global (weak) JNI handles
261 JNIHandles::weak_oops_do(&always_true, root_closure);
262
263 CodeCache::blobs_do(code_roots);
264 if (UseSharedSpaces && !DumpSharedSpaces) {
265 SkipAdjustingSharedStrings skip_closure(root_closure);
266 StringTable::oops_do(&skip_closure);
267 } else {
268 StringTable::oops_do(root_closure);
269 }
270 }
271
272 void SharedHeap::set_barrier_set(BarrierSet* bs) {
273 _barrier_set = bs;
274 // Cached barrier set for fast access in oops
275 oopDesc::set_bs(bs);
276 }
277
278 void SharedHeap::post_initialize() {
279 ref_processing_init();
280 }
281
282 void SharedHeap::ref_processing_init() {
283 perm_gen()->ref_processor_init();
284 }
285
286 // Some utilities.
287 void SharedHeap::print_size_transition(outputStream* out,
288 size_t bytes_before,
289 size_t bytes_after,
290 size_t capacity) {
291 out->print(" %d%s->%d%s(%d%s)",
292 byte_size_in_proper_unit(bytes_before),
293 proper_unit_for_byte_size(bytes_before),
294 byte_size_in_proper_unit(bytes_after),
295 proper_unit_for_byte_size(bytes_after),
296 byte_size_in_proper_unit(capacity),
297 proper_unit_for_byte_size(capacity));
298 }