1 /*
2 * Copyright (c) 2000, 2014, 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/stringTable.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/atomic.inline.hpp"
33 #include "runtime/fprofiler.hpp"
34 #include "runtime/java.hpp"
35 #include "services/management.hpp"
36 #include "utilities/copy.hpp"
37 #include "utilities/workgroup.hpp"
38
39 PRAGMA_FORMAT_MUTE_WARNINGS_FOR_GCC
40
41 SharedHeap* SharedHeap::_sh;
42
43 // The set of potentially parallel tasks in root scanning.
44 enum SH_process_roots_tasks {
45 SH_PS_Universe_oops_do,
46 SH_PS_JNIHandles_oops_do,
47 SH_PS_ObjectSynchronizer_oops_do,
48 SH_PS_FlatProfiler_oops_do,
49 SH_PS_Management_oops_do,
50 SH_PS_SystemDictionary_oops_do,
51 SH_PS_ClassLoaderDataGraph_oops_do,
52 SH_PS_jvmti_oops_do,
53 SH_PS_CodeCache_oops_do,
54 // Leave this one last.
55 SH_PS_NumElements
56 };
57
58 SharedHeap::SharedHeap(CollectorPolicy* policy_) :
59 CollectedHeap(),
60 _collector_policy(policy_),
61 _rem_set(NULL),
62 _strong_roots_scope(NULL),
63 _strong_roots_parity(0),
64 _process_strong_tasks(new SubTasksDone(SH_PS_NumElements)),
65 _workers(NULL)
66 {
67 if (_process_strong_tasks == NULL || !_process_strong_tasks->valid()) {
68 vm_exit_during_initialization("Failed necessary allocation.");
69 }
70 _sh = this; // ch is static, should be set only once.
71 if (UseParNewGC ||
72 UseG1GC ||
73 (UseConcMarkSweepGC && (CMSParallelInitialMarkEnabled || CMSParallelRemarkEnabled) && use_parallel_gc_threads())) {
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 int SharedHeap::n_termination() {
86 return _process_strong_tasks->n_threads();
87 }
88
89 void SharedHeap::set_n_termination(int t) {
90 _process_strong_tasks->set_n_threads(t);
91 }
92
93 bool SharedHeap::heap_lock_held_for_gc() {
94 Thread* t = Thread::current();
95 return Heap_lock->owned_by_self()
96 || ( (t->is_GC_task_thread() || t->is_VM_thread())
97 && _thread_holds_heap_lock_for_gc);
98 }
99
100 void SharedHeap::set_par_threads(uint t) {
101 assert(t == 0 || !UseSerialGC, "Cannot have parallel threads");
102 _n_par_threads = t;
103 _process_strong_tasks->set_n_threads(t);
104 }
105
106 #ifdef ASSERT
107 class AssertNonScavengableClosure: public OopClosure {
108 public:
109 virtual void do_oop(oop* p) {
110 assert(!Universe::heap()->is_in_partial_collection(*p),
111 "Referent should not be scavengable."); }
112 virtual void do_oop(narrowOop* p) { ShouldNotReachHere(); }
113 };
114 static AssertNonScavengableClosure assert_is_non_scavengable_closure;
115 #endif
116
117 SharedHeap::StrongRootsScope* SharedHeap::active_strong_roots_scope() const {
118 return _strong_roots_scope;
119 }
120 void SharedHeap::register_strong_roots_scope(SharedHeap::StrongRootsScope* scope) {
121 assert(_strong_roots_scope == NULL, "Should only have one StrongRootsScope active");
122 assert(scope != NULL, "Illegal argument");
123 _strong_roots_scope = scope;
124 }
125 void SharedHeap::unregister_strong_roots_scope(SharedHeap::StrongRootsScope* scope) {
126 assert(_strong_roots_scope == scope, "Wrong scope unregistered");
127 _strong_roots_scope = NULL;
128 }
129
130 void SharedHeap::change_strong_roots_parity() {
131 // Also set the new collection parity.
132 assert(_strong_roots_parity >= 0 && _strong_roots_parity <= 2,
133 "Not in range.");
134 _strong_roots_parity++;
135 if (_strong_roots_parity == 3) _strong_roots_parity = 1;
136 assert(_strong_roots_parity >= 1 && _strong_roots_parity <= 2,
137 "Not in range.");
138 }
139
140 SharedHeap::StrongRootsScope::StrongRootsScope(SharedHeap* heap, bool activate)
141 : MarkScope(activate), _sh(heap), _n_workers_done_with_threads(0)
142 {
143 if (_active) {
144 _sh->register_strong_roots_scope(this);
145 _sh->change_strong_roots_parity();
146 // Zero the claimed high water mark in the StringTable
147 StringTable::clear_parallel_claimed_index();
148 }
149 }
150
151 SharedHeap::StrongRootsScope::~StrongRootsScope() {
152 if (_active) {
153 _sh->unregister_strong_roots_scope(this);
154 }
155 }
156
157 Monitor* SharedHeap::StrongRootsScope::_lock = new Monitor(Mutex::leaf, "StrongRootsScope lock", false);
158
159 void SharedHeap::StrongRootsScope::mark_worker_done_with_threads(uint n_workers) {
160 // The Thread work barrier is only needed by G1 Class Unloading.
161 // No need to use the barrier if this is single-threaded code.
162 if (UseG1GC && ClassUnloadingWithConcurrentMark && n_workers > 0) {
163 uint new_value = (uint)Atomic::add(1, &_n_workers_done_with_threads);
164 if (new_value == n_workers) {
165 // This thread is last. Notify the others.
166 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
167 _lock->notify_all();
168 }
169 }
170 }
171
172 void SharedHeap::StrongRootsScope::wait_until_all_workers_done_with_threads(uint n_workers) {
173 assert(UseG1GC, "Currently only used by G1");
174 assert(ClassUnloadingWithConcurrentMark, "Currently only needed when doing G1 Class Unloading");
175
176 // No need to use the barrier if this is single-threaded code.
177 if (n_workers > 0 && (uint)_n_workers_done_with_threads != n_workers) {
178 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
179 while ((uint)_n_workers_done_with_threads != n_workers) {
180 _lock->wait(Mutex::_no_safepoint_check_flag, 0, false);
181 }
182 }
183 }
184
185 void SharedHeap::process_roots(bool activate_scope,
186 ScanningOption so,
187 OopClosure* strong_roots,
188 OopClosure* weak_roots,
189 CLDClosure* strong_cld_closure,
190 CLDClosure* weak_cld_closure,
191 CodeBlobClosure* code_roots) {
192 StrongRootsScope srs(this, activate_scope);
193
194 // General roots.
195 assert(_strong_roots_parity != 0, "must have called prologue code");
196 assert(code_roots != NULL, "code root closure should always be set");
197 // _n_termination for _process_strong_tasks should be set up stream
198 // in a method not running in a GC worker. Otherwise the GC worker
199 // could be trying to change the termination condition while the task
200 // is executing in another GC worker.
201
202 // Iterating over the CLDG and the Threads are done early to allow G1 to
203 // first process the strong CLDs and nmethods and then, after a barrier,
204 // let the thread process the weak CLDs and nmethods.
205
206 if (!_process_strong_tasks->is_task_claimed(SH_PS_ClassLoaderDataGraph_oops_do)) {
207 ClassLoaderDataGraph::roots_cld_do(strong_cld_closure, weak_cld_closure);
208 }
209
210 // Some CLDs contained in the thread frames should be considered strong.
211 // Don't process them if they will be processed during the ClassLoaderDataGraph phase.
212 CLDClosure* roots_from_clds_p = (strong_cld_closure != weak_cld_closure) ? strong_cld_closure : NULL;
213 // Only process code roots from thread stacks if we aren't visiting the entire CodeCache anyway
214 CodeBlobClosure* roots_from_code_p = (so & SO_AllCodeCache) ? NULL : code_roots;
215
216 Threads::possibly_parallel_oops_do(strong_roots, roots_from_clds_p, roots_from_code_p);
217
218 // This is the point where this worker thread will not find more strong CLDs/nmethods.
219 // Report this so G1 can synchronize the strong and weak CLDs/nmethods processing.
220 active_strong_roots_scope()->mark_worker_done_with_threads(n_par_threads());
221
222 if (!_process_strong_tasks->is_task_claimed(SH_PS_Universe_oops_do)) {
223 Universe::oops_do(strong_roots);
224 }
225 // Global (strong) JNI handles
226 if (!_process_strong_tasks->is_task_claimed(SH_PS_JNIHandles_oops_do))
227 JNIHandles::oops_do(strong_roots);
228
229 if (!_process_strong_tasks-> is_task_claimed(SH_PS_ObjectSynchronizer_oops_do))
230 ObjectSynchronizer::oops_do(strong_roots);
231 if (!_process_strong_tasks->is_task_claimed(SH_PS_FlatProfiler_oops_do))
232 FlatProfiler::oops_do(strong_roots);
233 if (!_process_strong_tasks->is_task_claimed(SH_PS_Management_oops_do))
234 Management::oops_do(strong_roots);
235 if (!_process_strong_tasks->is_task_claimed(SH_PS_jvmti_oops_do))
236 JvmtiExport::oops_do(strong_roots);
237
238 if (!_process_strong_tasks->is_task_claimed(SH_PS_SystemDictionary_oops_do)) {
239 SystemDictionary::roots_oops_do(strong_roots, weak_roots);
240 }
241
242 // All threads execute the following. A specific chunk of buckets
243 // from the StringTable are the individual tasks.
244 if (weak_roots != NULL) {
245 if (CollectedHeap::use_parallel_gc_threads()) {
246 StringTable::possibly_parallel_oops_do(weak_roots);
247 } else {
248 StringTable::oops_do(weak_roots);
249 }
250 }
251
252 if (!_process_strong_tasks->is_task_claimed(SH_PS_CodeCache_oops_do)) {
253 if (so & SO_ScavengeCodeCache) {
254 assert(code_roots != NULL, "must supply closure for code cache");
255
256 // We only visit parts of the CodeCache when scavenging.
257 CodeCache::scavenge_root_nmethods_do(code_roots);
258 }
259 if (so & SO_AllCodeCache) {
260 assert(code_roots != NULL, "must supply closure for code cache");
261
262 // CMSCollector uses this to do intermediate-strength collections.
263 // We scan the entire code cache, since CodeCache::do_unloading is not called.
264 CodeCache::blobs_do(code_roots);
265 }
266 // Verify that the code cache contents are not subject to
267 // movement by a scavenging collection.
268 DEBUG_ONLY(CodeBlobToOopClosure assert_code_is_non_scavengable(&assert_is_non_scavengable_closure, !CodeBlobToOopClosure::FixRelocations));
269 DEBUG_ONLY(CodeCache::asserted_non_scavengable_nmethods_do(&assert_code_is_non_scavengable));
270 }
271
272 _process_strong_tasks->all_tasks_completed();
273 }
274
275 void SharedHeap::process_all_roots(bool activate_scope,
276 ScanningOption so,
277 OopClosure* roots,
278 CLDClosure* cld_closure,
279 CodeBlobClosure* code_closure) {
280 process_roots(activate_scope, so,
281 roots, roots,
282 cld_closure, cld_closure,
283 code_closure);
284 }
285
286 void SharedHeap::process_strong_roots(bool activate_scope,
287 ScanningOption so,
288 OopClosure* roots,
289 CLDClosure* cld_closure,
290 CodeBlobClosure* code_closure) {
291 process_roots(activate_scope, so,
292 roots, NULL,
293 cld_closure, NULL,
294 code_closure);
295 }
296
297
298 class AlwaysTrueClosure: public BoolObjectClosure {
299 public:
300 bool do_object_b(oop p) { return true; }
301 };
302 static AlwaysTrueClosure always_true;
303
304 void SharedHeap::process_weak_roots(OopClosure* root_closure) {
305 // Global (weak) JNI handles
306 JNIHandles::weak_oops_do(&always_true, root_closure);
307 }
308
309 void SharedHeap::set_barrier_set(BarrierSet* bs) {
310 _barrier_set = bs;
311 // Cached barrier set for fast access in oops
312 oopDesc::set_bs(bs);
313 }
314
315 void SharedHeap::post_initialize() {
316 CollectedHeap::post_initialize();
317 ref_processing_init();
318 }
319
320 void SharedHeap::ref_processing_init() {}
321
322 // Some utilities.
323 void SharedHeap::print_size_transition(outputStream* out,
324 size_t bytes_before,
325 size_t bytes_after,
326 size_t capacity) {
327 out->print(" " SIZE_FORMAT "%s->" SIZE_FORMAT "%s(" SIZE_FORMAT "%s)",
328 byte_size_in_proper_unit(bytes_before),
329 proper_unit_for_byte_size(bytes_before),
330 byte_size_in_proper_unit(bytes_after),
331 proper_unit_for_byte_size(bytes_after),
332 byte_size_in_proper_unit(capacity),
333 proper_unit_for_byte_size(capacity));
334 }