1 /*
2 * Copyright (c) 2000, 2010, 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 "incls/_precompiled.incl"
26 # include "incls/_sharedHeap.cpp.incl"
27
28 SharedHeap* SharedHeap::_sh;
29
30 // The set of potentially parallel tasks in strong root scanning.
31 enum SH_process_strong_roots_tasks {
32 SH_PS_Universe_oops_do,
33 SH_PS_JNIHandles_oops_do,
34 SH_PS_ObjectSynchronizer_oops_do,
35 SH_PS_FlatProfiler_oops_do,
36 SH_PS_Management_oops_do,
37 SH_PS_SystemDictionary_oops_do,
38 SH_PS_jvmti_oops_do,
39 SH_PS_vmSymbols_oops_do,
40 SH_PS_SymbolTable_oops_do,
41 SH_PS_StringTable_oops_do,
42 SH_PS_CodeCache_oops_do,
43 // Leave this one last.
44 SH_PS_NumElements
45 };
46
47 SharedHeap::SharedHeap(CollectorPolicy* policy_) :
48 CollectedHeap(),
49 _collector_policy(policy_),
50 _perm_gen(NULL), _rem_set(NULL),
51 _strong_roots_parity(0),
52 _process_strong_tasks(new SubTasksDone(SH_PS_NumElements)),
53 _n_par_threads(0),
54 _workers(NULL)
55 {
56 if (_process_strong_tasks == NULL || !_process_strong_tasks->valid()) {
57 vm_exit_during_initialization("Failed necessary allocation.");
58 }
59 _sh = this; // ch is static, should be set only once.
60 if ((UseParNewGC ||
61 (UseConcMarkSweepGC && CMSParallelRemarkEnabled) ||
62 UseG1GC) &&
63 ParallelGCThreads > 0) {
64 _workers = new FlexibleWorkGang("Parallel GC Threads", ParallelGCThreads,
65 /* are_GC_task_threads */true,
66 /* are_ConcurrentGC_threads */false);
67 if (_workers == NULL) {
68 vm_exit_during_initialization("Failed necessary allocation.");
69 } else {
70 _workers->initialize_workers();
71 }
72 }
73 }
74
75 bool SharedHeap::heap_lock_held_for_gc() {
76 Thread* t = Thread::current();
77 return Heap_lock->owned_by_self()
78 || ( (t->is_GC_task_thread() || t->is_VM_thread())
79 && _thread_holds_heap_lock_for_gc);
80 }
81
82 void SharedHeap::set_par_threads(int t) {
83 assert(t == 0 || !UseSerialGC, "Cannot have parallel threads");
84 _n_par_threads = t;
85 _process_strong_tasks->set_n_threads(t);
86 }
87
88 class AssertIsPermClosure: public OopClosure {
89 public:
90 virtual void do_oop(oop* p) {
91 assert((*p) == NULL || (*p)->is_perm(), "Referent should be perm.");
92 }
93 virtual void do_oop(narrowOop* p) { ShouldNotReachHere(); }
94 };
95 static AssertIsPermClosure assert_is_perm_closure;
96
97 void SharedHeap::change_strong_roots_parity() {
98 // Also set the new collection parity.
99 assert(_strong_roots_parity >= 0 && _strong_roots_parity <= 2,
100 "Not in range.");
101 _strong_roots_parity++;
102 if (_strong_roots_parity == 3) _strong_roots_parity = 1;
103 assert(_strong_roots_parity >= 1 && _strong_roots_parity <= 2,
104 "Not in range.");
105 }
106
107 SharedHeap::StrongRootsScope::StrongRootsScope(SharedHeap* outer, bool activate)
108 : MarkScope(activate)
109 {
110 if (_active) {
111 outer->change_strong_roots_parity();
112 }
113 }
114
115 SharedHeap::StrongRootsScope::~StrongRootsScope() {
116 // nothing particular
117 }
118
119 void SharedHeap::process_strong_roots(bool activate_scope,
120 bool collecting_perm_gen,
121 ScanningOption so,
122 OopClosure* roots,
123 CodeBlobClosure* code_roots,
124 OopsInGenClosure* perm_blk) {
125 StrongRootsScope srs(this, activate_scope);
126 // General strong roots.
127 assert(_strong_roots_parity != 0, "must have called prologue code");
128 if (!_process_strong_tasks->is_task_claimed(SH_PS_Universe_oops_do)) {
129 Universe::oops_do(roots);
130 ReferenceProcessor::oops_do(roots);
131 // Consider perm-gen discovered lists to be strong.
132 perm_gen()->ref_processor()->weak_oops_do(roots);
133 }
134 // Global (strong) JNI handles
135 if (!_process_strong_tasks->is_task_claimed(SH_PS_JNIHandles_oops_do))
136 JNIHandles::oops_do(roots);
137 // All threads execute this; the individual threads are task groups.
138 if (ParallelGCThreads > 0) {
139 Threads::possibly_parallel_oops_do(roots, code_roots);
140 } else {
141 Threads::oops_do(roots, code_roots);
142 }
143 if (!_process_strong_tasks-> is_task_claimed(SH_PS_ObjectSynchronizer_oops_do))
144 ObjectSynchronizer::oops_do(roots);
145 if (!_process_strong_tasks->is_task_claimed(SH_PS_FlatProfiler_oops_do))
146 FlatProfiler::oops_do(roots);
147 if (!_process_strong_tasks->is_task_claimed(SH_PS_Management_oops_do))
148 Management::oops_do(roots);
149 if (!_process_strong_tasks->is_task_claimed(SH_PS_jvmti_oops_do))
150 JvmtiExport::oops_do(roots);
151
152 if (!_process_strong_tasks->is_task_claimed(SH_PS_SystemDictionary_oops_do)) {
153 if (so & SO_AllClasses) {
154 SystemDictionary::oops_do(roots);
155 } else
156 if (so & SO_SystemClasses) {
157 SystemDictionary::always_strong_oops_do(roots);
158 }
159 }
160
161 if (!_process_strong_tasks->is_task_claimed(SH_PS_SymbolTable_oops_do)) {
162 if (so & SO_Symbols) {
163 SymbolTable::oops_do(roots);
164 }
165 // Verify if the symbol table contents are in the perm gen
166 NOT_PRODUCT(SymbolTable::oops_do(&assert_is_perm_closure));
167 }
168
169 if (!_process_strong_tasks->is_task_claimed(SH_PS_StringTable_oops_do)) {
170 if (so & SO_Strings) {
171 StringTable::oops_do(roots);
172 }
173 // Verify if the string table contents are in the perm gen
174 NOT_PRODUCT(StringTable::oops_do(&assert_is_perm_closure));
175 }
176
177 if (!_process_strong_tasks->is_task_claimed(SH_PS_CodeCache_oops_do)) {
178 if (so & SO_CodeCache) {
179 // (Currently, CMSCollector uses this to do intermediate-strength collections.)
180 assert(collecting_perm_gen, "scanning all of code cache");
181 assert(code_roots != NULL, "must supply closure for code cache");
182 if (code_roots != NULL) {
183 CodeCache::blobs_do(code_roots);
184 }
185 } else if (so & (SO_SystemClasses|SO_AllClasses)) {
186 if (!collecting_perm_gen) {
187 // If we are collecting from class statics, but we are not going to
188 // visit all of the CodeCache, collect from the non-perm roots if any.
189 // This makes the code cache function temporarily as a source of strong
190 // roots for oops, until the next major collection.
191 //
192 // If collecting_perm_gen is true, we require that this phase will call
193 // CodeCache::do_unloading. This will kill off nmethods with expired
194 // weak references, such as stale invokedynamic targets.
195 CodeCache::scavenge_root_nmethods_do(code_roots);
196 }
197 }
198 // Verify if the code cache contents are in the perm gen
199 NOT_PRODUCT(CodeBlobToOopClosure assert_code_is_perm(&assert_is_perm_closure, /*do_marking=*/ false));
200 NOT_PRODUCT(CodeCache::asserted_non_scavengable_nmethods_do(&assert_code_is_perm));
201 }
202
203 // Roots that should point only into permanent generation.
204 {
205 OopClosure* blk = NULL;
206 if (collecting_perm_gen) {
207 blk = roots;
208 } else {
209 debug_only(blk = &assert_is_perm_closure);
210 }
211 if (blk != NULL) {
212 if (!_process_strong_tasks->is_task_claimed(SH_PS_vmSymbols_oops_do))
213 vmSymbols::oops_do(blk);
214 }
215 }
216
217 if (!collecting_perm_gen) {
218 // All threads perform this; coordination is handled internally.
219
220 rem_set()->younger_refs_iterate(perm_gen(), perm_blk);
221 }
222 _process_strong_tasks->all_tasks_completed();
223 }
224
225 class AlwaysTrueClosure: public BoolObjectClosure {
226 public:
227 void do_object(oop p) { ShouldNotReachHere(); }
228 bool do_object_b(oop p) { return true; }
229 };
230 static AlwaysTrueClosure always_true;
231
232 class SkipAdjustingSharedStrings: public OopClosure {
233 OopClosure* _clo;
234 public:
235 SkipAdjustingSharedStrings(OopClosure* clo) : _clo(clo) {}
236
237 virtual void do_oop(oop* p) {
238 oop o = (*p);
239 if (!o->is_shared_readwrite()) {
240 _clo->do_oop(p);
241 }
242 }
243 virtual void do_oop(narrowOop* p) { ShouldNotReachHere(); }
244 };
245
246 // Unmarked shared Strings in the StringTable (which got there due to
247 // being in the constant pools of as-yet unloaded shared classes) were
248 // not marked and therefore did not have their mark words preserved.
249 // These entries are also deliberately not purged from the string
250 // table during unloading of unmarked strings. If an identity hash
251 // code was computed for any of these objects, it will not have been
252 // cleared to zero during the forwarding process or by the
253 // RecursiveAdjustSharedObjectClosure, and will be confused by the
254 // adjusting process as a forwarding pointer. We need to skip
255 // forwarding StringTable entries which contain unmarked shared
256 // Strings. Actually, since shared strings won't be moving, we can
257 // just skip adjusting any shared entries in the string table.
258
259 void SharedHeap::process_weak_roots(OopClosure* root_closure,
260 CodeBlobClosure* code_roots,
261 OopClosure* non_root_closure) {
262 // Global (weak) JNI handles
263 JNIHandles::weak_oops_do(&always_true, root_closure);
264
265 CodeCache::blobs_do(code_roots);
266 SymbolTable::oops_do(root_closure);
267 if (UseSharedSpaces && !DumpSharedSpaces) {
268 SkipAdjustingSharedStrings skip_closure(root_closure);
269 StringTable::oops_do(&skip_closure);
270 } else {
271 StringTable::oops_do(root_closure);
272 }
273 }
274
275 void SharedHeap::set_barrier_set(BarrierSet* bs) {
276 _barrier_set = bs;
277 // Cached barrier set for fast access in oops
278 oopDesc::set_bs(bs);
279 }
280
281 void SharedHeap::post_initialize() {
282 ref_processing_init();
283 }
284
285 void SharedHeap::ref_processing_init() {
286 perm_gen()->ref_processor_init();
287 }
288
289 // Some utilities.
290 void SharedHeap::print_size_transition(outputStream* out,
291 size_t bytes_before,
292 size_t bytes_after,
293 size_t capacity) {
294 out->print(" %d%s->%d%s(%d%s)",
295 byte_size_in_proper_unit(bytes_before),
296 proper_unit_for_byte_size(bytes_before),
297 byte_size_in_proper_unit(bytes_after),
298 proper_unit_for_byte_size(bytes_after),
299 byte_size_in_proper_unit(capacity),
300 proper_unit_for_byte_size(capacity));
301 }