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 _workers(NULL), _n_par_threads(0)
64 {
65 if (_process_strong_tasks == NULL || !_process_strong_tasks->valid()) {
66 vm_exit_during_initialization("Failed necessary allocation.");
67 }
68 _sh = this; // ch is static, should be set only once.
69 if ((UseParNewGC ||
70 (UseConcMarkSweepGC && CMSParallelRemarkEnabled) ||
71 UseG1GC) &&
72 ParallelGCThreads > 0) {
73 _workers = new WorkGang("Parallel GC Threads", ParallelGCThreads,
74 /* are_GC_task_threads */true,
75 /* are_ConcurrentGC_threads */false);
76 if (_workers == NULL) {
77 vm_exit_during_initialization("Failed necessary allocation.");
78 }
79 }
80 }
81
82 bool SharedHeap::heap_lock_held_for_gc() {
83 Thread* t = Thread::current();
84 return Heap_lock->owned_by_self()
85 || ( (t->is_GC_task_thread() || t->is_VM_thread())
86 && _thread_holds_heap_lock_for_gc);
87 }
88
89 void SharedHeap::set_par_threads(int t) {
90 _n_par_threads = t;
91 _process_strong_tasks->set_par_threads(t);
92 }
93
94 class AssertIsPermClosure: public OopClosure {
95 public:
96 virtual void do_oop(oop* p) {
97 assert((*p) == NULL || (*p)->is_perm(), "Referent should be perm.");
98 }
99 virtual void do_oop(narrowOop* p) { ShouldNotReachHere(); }
100 };
101 static AssertIsPermClosure assert_is_perm_closure;
102
103 void SharedHeap::change_strong_roots_parity() {
104 // Also set the new collection parity.
105 assert(_strong_roots_parity >= 0 && _strong_roots_parity <= 2,
106 "Not in range.");
107 _strong_roots_parity++;
108 if (_strong_roots_parity == 3) _strong_roots_parity = 1;
109 assert(_strong_roots_parity >= 1 && _strong_roots_parity <= 2,
110 "Not in range.");
111 }
112
113 SharedHeap::StrongRootsScope::StrongRootsScope(SharedHeap* outer, bool activate)
114 : MarkScope(activate)
115 {
116 if (_active) {
117 outer->change_strong_roots_parity();
118 }
119 }
120
121 SharedHeap::StrongRootsScope::~StrongRootsScope() {
122 // nothing particular
123 }
124
125 void SharedHeap::process_strong_roots(bool activate_scope,
126 bool collecting_perm_gen,
127 ScanningOption so,
128 OopClosure* roots,
129 CodeBlobClosure* code_roots,
130 OopsInGenClosure* perm_blk) {
131 StrongRootsScope srs(this, activate_scope);
132 // General strong roots.
133 assert(_strong_roots_parity != 0, "must have called prologue code");
134 if (!_process_strong_tasks->is_task_claimed(SH_PS_Universe_oops_do)) {
135 Universe::oops_do(roots);
136 ReferenceProcessor::oops_do(roots);
137 // Consider perm-gen discovered lists to be strong.
138 perm_gen()->ref_processor()->weak_oops_do(roots);
139 }
140 // Global (strong) JNI handles
141 if (!_process_strong_tasks->is_task_claimed(SH_PS_JNIHandles_oops_do))
142 JNIHandles::oops_do(roots);
143 // All threads execute this; the individual threads are task groups.
144 if (ParallelGCThreads > 0) {
145 Threads::possibly_parallel_oops_do(roots, code_roots);
146 } else {
147 Threads::oops_do(roots, code_roots);
148 }
149 if (!_process_strong_tasks-> is_task_claimed(SH_PS_ObjectSynchronizer_oops_do))
150 ObjectSynchronizer::oops_do(roots);
151 if (!_process_strong_tasks->is_task_claimed(SH_PS_FlatProfiler_oops_do))
152 FlatProfiler::oops_do(roots);
153 if (!_process_strong_tasks->is_task_claimed(SH_PS_Management_oops_do))
154 Management::oops_do(roots);
155 if (!_process_strong_tasks->is_task_claimed(SH_PS_jvmti_oops_do))
156 JvmtiExport::oops_do(roots);
157
158 if (!_process_strong_tasks->is_task_claimed(SH_PS_SystemDictionary_oops_do)) {
159 if (so & SO_AllClasses) {
160 SystemDictionary::oops_do(roots);
161 } else
162 if (so & SO_SystemClasses) {
163 SystemDictionary::always_strong_oops_do(roots);
164 }
165 }
166
167 if (!_process_strong_tasks->is_task_claimed(SH_PS_SymbolTable_oops_do)) {
168 if (so & SO_Symbols) {
169 SymbolTable::oops_do(roots);
170 }
171 // Verify if the symbol table contents are in the perm gen
172 NOT_PRODUCT(SymbolTable::oops_do(&assert_is_perm_closure));
173 }
174
175 if (!_process_strong_tasks->is_task_claimed(SH_PS_StringTable_oops_do)) {
176 if (so & SO_Strings) {
177 StringTable::oops_do(roots);
178 }
179 // Verify if the string table contents are in the perm gen
180 NOT_PRODUCT(StringTable::oops_do(&assert_is_perm_closure));
181 }
182
183 if (!_process_strong_tasks->is_task_claimed(SH_PS_CodeCache_oops_do)) {
184 if (so & SO_CodeCache) {
185 // (Currently, CMSCollector uses this to do intermediate-strength collections.)
186 assert(collecting_perm_gen, "scanning all of code cache");
187 assert(code_roots != NULL, "must supply closure for code cache");
188 if (code_roots != NULL) {
189 CodeCache::blobs_do(code_roots);
190 }
191 } else if (so & (SO_SystemClasses|SO_AllClasses)) {
192 if (!collecting_perm_gen) {
193 // If we are collecting from class statics, but we are not going to
194 // visit all of the CodeCache, collect from the non-perm roots if any.
195 // This makes the code cache function temporarily as a source of strong
196 // roots for oops, until the next major collection.
197 //
198 // If collecting_perm_gen is true, we require that this phase will call
199 // CodeCache::do_unloading. This will kill off nmethods with expired
200 // weak references, such as stale invokedynamic targets.
201 CodeCache::scavenge_root_nmethods_do(code_roots);
202 }
203 }
204 // Verify if the code cache contents are in the perm gen
205 NOT_PRODUCT(CodeBlobToOopClosure assert_code_is_perm(&assert_is_perm_closure, /*do_marking=*/ false));
206 NOT_PRODUCT(CodeCache::asserted_non_scavengable_nmethods_do(&assert_code_is_perm));
207 }
208
209 // Roots that should point only into permanent generation.
210 {
211 OopClosure* blk = NULL;
212 if (collecting_perm_gen) {
213 blk = roots;
214 } else {
215 debug_only(blk = &assert_is_perm_closure);
216 }
217 if (blk != NULL) {
218 if (!_process_strong_tasks->is_task_claimed(SH_PS_vmSymbols_oops_do))
219 vmSymbols::oops_do(blk);
220 }
221 }
222
223 if (!collecting_perm_gen) {
224 // All threads perform this; coordination is handled internally.
225
226 rem_set()->younger_refs_iterate(perm_gen(), perm_blk);
227 }
228 _process_strong_tasks->all_tasks_completed();
229 }
230
231 class AlwaysTrueClosure: public BoolObjectClosure {
232 public:
233 void do_object(oop p) { ShouldNotReachHere(); }
234 bool do_object_b(oop p) { return true; }
235 };
236 static AlwaysTrueClosure always_true;
237
238 class SkipAdjustingSharedStrings: public OopClosure {
239 OopClosure* _clo;
240 public:
241 SkipAdjustingSharedStrings(OopClosure* clo) : _clo(clo) {}
242
243 virtual void do_oop(oop* p) {
244 oop o = (*p);
245 if (!o->is_shared_readwrite()) {
246 _clo->do_oop(p);
247 }
248 }
249 virtual void do_oop(narrowOop* p) { ShouldNotReachHere(); }
250 };
251
252 // Unmarked shared Strings in the StringTable (which got there due to
253 // being in the constant pools of as-yet unloaded shared classes) were
254 // not marked and therefore did not have their mark words preserved.
255 // These entries are also deliberately not purged from the string
256 // table during unloading of unmarked strings. If an identity hash
257 // code was computed for any of these objects, it will not have been
258 // cleared to zero during the forwarding process or by the
259 // RecursiveAdjustSharedObjectClosure, and will be confused by the
260 // adjusting process as a forwarding pointer. We need to skip
261 // forwarding StringTable entries which contain unmarked shared
262 // Strings. Actually, since shared strings won't be moving, we can
263 // just skip adjusting any shared entries in the string table.
264
265 void SharedHeap::process_weak_roots(OopClosure* root_closure,
266 CodeBlobClosure* code_roots,
267 OopClosure* non_root_closure) {
268 // Global (weak) JNI handles
269 JNIHandles::weak_oops_do(&always_true, root_closure);
270
271 CodeCache::blobs_do(code_roots);
272 SymbolTable::oops_do(root_closure);
273 if (UseSharedSpaces && !DumpSharedSpaces) {
274 SkipAdjustingSharedStrings skip_closure(root_closure);
275 StringTable::oops_do(&skip_closure);
276 } else {
277 StringTable::oops_do(root_closure);
278 }
279 }
280
281 void SharedHeap::set_barrier_set(BarrierSet* bs) {
282 _barrier_set = bs;
283 // Cached barrier set for fast access in oops
284 oopDesc::set_bs(bs);
285 }
286
287 void SharedHeap::post_initialize() {
288 ref_processing_init();
289 }
290
291 void SharedHeap::ref_processing_init() {
292 perm_gen()->ref_processor_init();
293 }
294
295 // Some utilities.
296 void SharedHeap::print_size_transition(outputStream* out,
297 size_t bytes_before,
298 size_t bytes_after,
299 size_t capacity) {
300 out->print(" %d%s->%d%s(%d%s)",
301 byte_size_in_proper_unit(bytes_before),
302 proper_unit_for_byte_size(bytes_before),
303 byte_size_in_proper_unit(bytes_after),
304 proper_unit_for_byte_size(bytes_after),
305 byte_size_in_proper_unit(capacity),
306 proper_unit_for_byte_size(capacity));
307 }