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 "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_vmSymbols_oops_do,
50 SH_PS_SymbolTable_oops_do,
51 SH_PS_StringTable_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 _perm_gen(NULL), _rem_set(NULL),
61 _strong_roots_parity(0),
62 _process_strong_tasks(new SubTasksDone(SH_PS_NumElements)),
63 _n_par_threads(0),
64 _workers(NULL)
65 {
66 if (_process_strong_tasks == NULL || !_process_strong_tasks->valid()) {
67 vm_exit_during_initialization("Failed necessary allocation.");
68 }
69 _sh = this; // ch is static, should be set only once.
70 if ((UseParNewGC ||
71 (UseConcMarkSweepGC && 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 bool SharedHeap::heap_lock_held_for_gc() {
86 Thread* t = Thread::current();
87 return Heap_lock->owned_by_self()
88 || ( (t->is_GC_task_thread() || t->is_VM_thread())
89 && _thread_holds_heap_lock_for_gc);
90 }
91
92 void SharedHeap::set_par_threads(int t) {
93 assert(t == 0 || !UseSerialGC, "Cannot have parallel threads");
94 _n_par_threads = t;
95 _process_strong_tasks->set_n_threads(t);
96 }
97
98 class AssertIsPermClosure: public OopClosure {
99 public:
100 virtual void do_oop(oop* p) {
101 assert((*p) == NULL || (*p)->is_perm(), "Referent should be perm.");
102 }
103 virtual void do_oop(narrowOop* p) { ShouldNotReachHere(); }
104 };
105 static AssertIsPermClosure assert_is_perm_closure;
106
107 void SharedHeap::change_strong_roots_parity() {
108 // Also set the new collection parity.
109 assert(_strong_roots_parity >= 0 && _strong_roots_parity <= 2,
110 "Not in range.");
111 _strong_roots_parity++;
112 if (_strong_roots_parity == 3) _strong_roots_parity = 1;
113 assert(_strong_roots_parity >= 1 && _strong_roots_parity <= 2,
114 "Not in range.");
115 }
116
117 SharedHeap::StrongRootsScope::StrongRootsScope(SharedHeap* outer, bool activate)
118 : MarkScope(activate)
119 {
120 if (_active) {
121 outer->change_strong_roots_parity();
122 }
123 }
124
125 SharedHeap::StrongRootsScope::~StrongRootsScope() {
126 // nothing particular
127 }
128
129 void SharedHeap::process_strong_roots(bool activate_scope,
130 bool collecting_perm_gen,
131 ScanningOption so,
132 OopClosure* roots,
133 CodeBlobClosure* code_roots,
134 OopsInGenClosure* perm_blk) {
135 StrongRootsScope srs(this, activate_scope);
136 // General strong roots.
137 assert(_strong_roots_parity != 0, "must have called prologue code");
138 if (!_process_strong_tasks->is_task_claimed(SH_PS_Universe_oops_do)) {
139 Universe::oops_do(roots);
140 ReferenceProcessor::oops_do(roots);
141 // Consider perm-gen discovered lists to be strong.
142 perm_gen()->ref_processor()->weak_oops_do(roots);
143 }
144 // Global (strong) JNI handles
145 if (!_process_strong_tasks->is_task_claimed(SH_PS_JNIHandles_oops_do))
146 JNIHandles::oops_do(roots);
147 // All threads execute this; the individual threads are task groups.
148 if (ParallelGCThreads > 0) {
149 Threads::possibly_parallel_oops_do(roots, code_roots);
150 } else {
151 Threads::oops_do(roots, code_roots);
152 }
153 if (!_process_strong_tasks-> is_task_claimed(SH_PS_ObjectSynchronizer_oops_do))
154 ObjectSynchronizer::oops_do(roots);
155 if (!_process_strong_tasks->is_task_claimed(SH_PS_FlatProfiler_oops_do))
156 FlatProfiler::oops_do(roots);
157 if (!_process_strong_tasks->is_task_claimed(SH_PS_Management_oops_do))
158 Management::oops_do(roots);
159 if (!_process_strong_tasks->is_task_claimed(SH_PS_jvmti_oops_do))
160 JvmtiExport::oops_do(roots);
161
162 if (!_process_strong_tasks->is_task_claimed(SH_PS_SystemDictionary_oops_do)) {
163 if (so & SO_AllClasses) {
164 SystemDictionary::oops_do(roots);
165 } else
166 if (so & SO_SystemClasses) {
167 SystemDictionary::always_strong_oops_do(roots);
168 }
169 }
170
171 if (!_process_strong_tasks->is_task_claimed(SH_PS_SymbolTable_oops_do)) {
172 if (so & SO_Symbols) {
173 SymbolTable::oops_do(roots);
174 }
175 // Verify if the symbol table contents are in the perm gen
176 NOT_PRODUCT(SymbolTable::oops_do(&assert_is_perm_closure));
177 }
178
179 if (!_process_strong_tasks->is_task_claimed(SH_PS_StringTable_oops_do)) {
180 if (so & SO_Strings) {
181 StringTable::oops_do(roots);
182 }
183 // Verify if the string table contents are in the perm gen
184 NOT_PRODUCT(StringTable::oops_do(&assert_is_perm_closure));
185 }
186
187 if (!_process_strong_tasks->is_task_claimed(SH_PS_CodeCache_oops_do)) {
188 if (so & SO_CodeCache) {
189 // (Currently, CMSCollector uses this to do intermediate-strength collections.)
190 assert(collecting_perm_gen, "scanning all of code cache");
191 assert(code_roots != NULL, "must supply closure for code cache");
192 if (code_roots != NULL) {
193 CodeCache::blobs_do(code_roots);
194 }
195 } else if (so & (SO_SystemClasses|SO_AllClasses)) {
196 if (!collecting_perm_gen) {
197 // If we are collecting from class statics, but we are not going to
198 // visit all of the CodeCache, collect from the non-perm roots if any.
199 // This makes the code cache function temporarily as a source of strong
200 // roots for oops, until the next major collection.
201 //
202 // If collecting_perm_gen is true, we require that this phase will call
203 // CodeCache::do_unloading. This will kill off nmethods with expired
204 // weak references, such as stale invokedynamic targets.
205 CodeCache::scavenge_root_nmethods_do(code_roots);
206 }
207 }
208 // Verify if the code cache contents are in the perm gen
209 NOT_PRODUCT(CodeBlobToOopClosure assert_code_is_perm(&assert_is_perm_closure, /*do_marking=*/ false));
210 NOT_PRODUCT(CodeCache::asserted_non_scavengable_nmethods_do(&assert_code_is_perm));
211 }
212
213 // Roots that should point only into permanent generation.
214 {
215 OopClosure* blk = NULL;
216 if (collecting_perm_gen) {
217 blk = roots;
218 } else {
219 debug_only(blk = &assert_is_perm_closure);
220 }
221 if (blk != NULL) {
222 if (!_process_strong_tasks->is_task_claimed(SH_PS_vmSymbols_oops_do))
223 vmSymbols::oops_do(blk);
224 }
225 }
226
227 if (!collecting_perm_gen) {
228 // All threads perform this; coordination is handled internally.
229
230 rem_set()->younger_refs_iterate(perm_gen(), perm_blk);
231 }
232 _process_strong_tasks->all_tasks_completed();
233 }
234
235 class AlwaysTrueClosure: public BoolObjectClosure {
236 public:
237 void do_object(oop p) { ShouldNotReachHere(); }
238 bool do_object_b(oop p) { return true; }
239 };
240 static AlwaysTrueClosure always_true;
241
242 class SkipAdjustingSharedStrings: public OopClosure {
243 OopClosure* _clo;
244 public:
245 SkipAdjustingSharedStrings(OopClosure* clo) : _clo(clo) {}
246
247 virtual void do_oop(oop* p) {
248 oop o = (*p);
249 if (!o->is_shared_readwrite()) {
250 _clo->do_oop(p);
251 }
252 }
253 virtual void do_oop(narrowOop* p) { ShouldNotReachHere(); }
254 };
255
256 // Unmarked shared Strings in the StringTable (which got there due to
257 // being in the constant pools of as-yet unloaded shared classes) were
258 // not marked and therefore did not have their mark words preserved.
259 // These entries are also deliberately not purged from the string
260 // table during unloading of unmarked strings. If an identity hash
261 // code was computed for any of these objects, it will not have been
262 // cleared to zero during the forwarding process or by the
263 // RecursiveAdjustSharedObjectClosure, and will be confused by the
264 // adjusting process as a forwarding pointer. We need to skip
265 // forwarding StringTable entries which contain unmarked shared
266 // Strings. Actually, since shared strings won't be moving, we can
267 // just skip adjusting any shared entries in the string table.
268
269 void SharedHeap::process_weak_roots(OopClosure* root_closure,
270 CodeBlobClosure* code_roots,
271 OopClosure* non_root_closure) {
272 // Global (weak) JNI handles
273 JNIHandles::weak_oops_do(&always_true, root_closure);
274
275 CodeCache::blobs_do(code_roots);
276 SymbolTable::oops_do(root_closure);
277 if (UseSharedSpaces && !DumpSharedSpaces) {
278 SkipAdjustingSharedStrings skip_closure(root_closure);
279 StringTable::oops_do(&skip_closure);
280 } else {
281 StringTable::oops_do(root_closure);
282 }
283 }
284
285 void SharedHeap::set_barrier_set(BarrierSet* bs) {
286 _barrier_set = bs;
287 // Cached barrier set for fast access in oops
288 oopDesc::set_bs(bs);
289 }
290
291 void SharedHeap::post_initialize() {
292 ref_processing_init();
293 }
294
295 void SharedHeap::ref_processing_init() {
296 perm_gen()->ref_processor_init();
297 }
298
299 // Some utilities.
300 void SharedHeap::print_size_transition(outputStream* out,
301 size_t bytes_before,
302 size_t bytes_after,
303 size_t capacity) {
304 out->print(" %d%s->%d%s(%d%s)",
305 byte_size_in_proper_unit(bytes_before),
306 proper_unit_for_byte_size(bytes_before),
307 byte_size_in_proper_unit(bytes_after),
308 proper_unit_for_byte_size(bytes_after),
309 byte_size_in_proper_unit(capacity),
310 proper_unit_for_byte_size(capacity));
311 }