1 /*
2 * Copyright (c) 2000, 2015, 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 _strong_roots_scope(NULL),
62 _strong_roots_parity(0),
63 _process_strong_tasks(new SubTasksDone(SH_PS_NumElements)),
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 (UseConcMarkSweepGC || UseG1GC) {
71 _workers = new FlexibleWorkGang("GC Thread", ParallelGCThreads,
72 /* are_GC_task_threads */true,
73 /* are_ConcurrentGC_threads */false);
74 if (_workers == NULL) {
75 vm_exit_during_initialization("Failed necessary allocation.");
76 } else {
77 _workers->initialize_workers();
78 }
79 }
80 }
81
82 int SharedHeap::n_termination() {
83 return _process_strong_tasks->n_threads();
84 }
85
86 void SharedHeap::set_n_termination(int t) {
87 _process_strong_tasks->set_n_threads(t);
88 }
89
90 bool SharedHeap::heap_lock_held_for_gc() {
91 Thread* t = Thread::current();
92 return Heap_lock->owned_by_self()
93 || ( (t->is_GC_task_thread() || t->is_VM_thread())
94 && _thread_holds_heap_lock_for_gc);
95 }
96
97 void SharedHeap::set_par_threads(uint t) {
98 assert(t == 0 || !UseSerialGC, "Cannot have parallel threads");
99 _n_par_threads = t;
100 _process_strong_tasks->set_n_threads(t);
101 }
102
103 #ifdef ASSERT
104 class AssertNonScavengableClosure: public OopClosure {
105 public:
106 virtual void do_oop(oop* p) {
107 assert(!Universe::heap()->is_in_partial_collection(*p),
108 "Referent should not be scavengable."); }
109 virtual void do_oop(narrowOop* p) { ShouldNotReachHere(); }
110 };
111 static AssertNonScavengableClosure assert_is_non_scavengable_closure;
112 #endif
113
114 SharedHeap::StrongRootsScope* SharedHeap::active_strong_roots_scope() const {
115 return _strong_roots_scope;
116 }
117 void SharedHeap::register_strong_roots_scope(SharedHeap::StrongRootsScope* scope) {
118 assert(_strong_roots_scope == NULL, "Should only have one StrongRootsScope active");
119 assert(scope != NULL, "Illegal argument");
120 _strong_roots_scope = scope;
121 }
122 void SharedHeap::unregister_strong_roots_scope(SharedHeap::StrongRootsScope* scope) {
123 assert(_strong_roots_scope == scope, "Wrong scope unregistered");
124 _strong_roots_scope = NULL;
125 }
126
127 void SharedHeap::change_strong_roots_parity() {
128 // Also set the new collection parity.
129 assert(_strong_roots_parity >= 0 && _strong_roots_parity <= 2,
130 "Not in range.");
131 _strong_roots_parity++;
132 if (_strong_roots_parity == 3) _strong_roots_parity = 1;
133 assert(_strong_roots_parity >= 1 && _strong_roots_parity <= 2,
134 "Not in range.");
135 }
136
137 SharedHeap::StrongRootsScope::StrongRootsScope(SharedHeap* heap, bool activate)
138 : MarkScope(activate), _sh(heap), _n_workers_done_with_threads(0)
139 {
140 if (_active) {
141 _sh->register_strong_roots_scope(this);
142 _sh->change_strong_roots_parity();
143 // Zero the claimed high water mark in the StringTable
144 StringTable::clear_parallel_claimed_index();
145 }
146 }
147
148 SharedHeap::StrongRootsScope::~StrongRootsScope() {
149 if (_active) {
150 _sh->unregister_strong_roots_scope(this);
151 }
152 }
153
154 Monitor* SharedHeap::StrongRootsScope::_lock = new Monitor(Mutex::leaf, "StrongRootsScope lock", false, Monitor::_safepoint_check_never);
155
156 void SharedHeap::StrongRootsScope::mark_worker_done_with_threads(uint n_workers) {
157 // The Thread work barrier is only needed by G1 Class Unloading.
158 // No need to use the barrier if this is single-threaded code.
159 if (UseG1GC && ClassUnloadingWithConcurrentMark && n_workers > 0) {
160 uint new_value = (uint)Atomic::add(1, &_n_workers_done_with_threads);
161 if (new_value == n_workers) {
162 // This thread is last. Notify the others.
163 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
164 _lock->notify_all();
165 }
166 }
167 }
168
169 void SharedHeap::StrongRootsScope::wait_until_all_workers_done_with_threads(uint n_workers) {
170 assert(UseG1GC, "Currently only used by G1");
171 assert(ClassUnloadingWithConcurrentMark, "Currently only needed when doing G1 Class Unloading");
172
173 // No need to use the barrier if this is single-threaded code.
174 if (n_workers > 0 && (uint)_n_workers_done_with_threads != n_workers) {
175 MonitorLockerEx ml(_lock, Mutex::_no_safepoint_check_flag);
176 while ((uint)_n_workers_done_with_threads != n_workers) {
177 _lock->wait(Mutex::_no_safepoint_check_flag, 0, false);
178 }
179 }
180 }
181
182 void SharedHeap::process_roots(bool activate_scope,
183 ScanningOption so,
184 OopClosure* strong_roots,
185 OopClosure* weak_roots,
186 CLDClosure* strong_cld_closure,
187 CLDClosure* weak_cld_closure,
188 CodeBlobClosure* code_roots) {
189 StrongRootsScope srs(this, activate_scope);
190
191 // General roots.
192 assert(_strong_roots_parity != 0, "must have called prologue code");
193 assert(code_roots != NULL, "code root closure should always be set");
194 // _n_termination for _process_strong_tasks should be set up stream
195 // in a method not running in a GC worker. Otherwise the GC worker
196 // could be trying to change the termination condition while the task
197 // is executing in another GC worker.
198
199 // Iterating over the CLDG and the Threads are done early to allow G1 to
200 // first process the strong CLDs and nmethods and then, after a barrier,
201 // let the thread process the weak CLDs and nmethods.
202
203 if (!_process_strong_tasks->is_task_claimed(SH_PS_ClassLoaderDataGraph_oops_do)) {
204 ClassLoaderDataGraph::roots_cld_do(strong_cld_closure, weak_cld_closure);
205 }
206
207 // Some CLDs contained in the thread frames should be considered strong.
208 // Don't process them if they will be processed during the ClassLoaderDataGraph phase.
209 CLDClosure* roots_from_clds_p = (strong_cld_closure != weak_cld_closure) ? strong_cld_closure : NULL;
210 // Only process code roots from thread stacks if we aren't visiting the entire CodeCache anyway
211 CodeBlobClosure* roots_from_code_p = (so & SO_AllCodeCache) ? NULL : code_roots;
212
213 Threads::possibly_parallel_oops_do(strong_roots, roots_from_clds_p, roots_from_code_p);
214
215 // This is the point where this worker thread will not find more strong CLDs/nmethods.
216 // Report this so G1 can synchronize the strong and weak CLDs/nmethods processing.
217 active_strong_roots_scope()->mark_worker_done_with_threads(n_par_threads());
218
219 if (!_process_strong_tasks->is_task_claimed(SH_PS_Universe_oops_do)) {
220 Universe::oops_do(strong_roots);
221 }
222 // Global (strong) JNI handles
223 if (!_process_strong_tasks->is_task_claimed(SH_PS_JNIHandles_oops_do))
224 JNIHandles::oops_do(strong_roots);
225
226 if (!_process_strong_tasks-> is_task_claimed(SH_PS_ObjectSynchronizer_oops_do))
227 ObjectSynchronizer::oops_do(strong_roots);
228 if (!_process_strong_tasks->is_task_claimed(SH_PS_FlatProfiler_oops_do))
229 FlatProfiler::oops_do(strong_roots);
230 if (!_process_strong_tasks->is_task_claimed(SH_PS_Management_oops_do))
231 Management::oops_do(strong_roots);
232 if (!_process_strong_tasks->is_task_claimed(SH_PS_jvmti_oops_do))
233 JvmtiExport::oops_do(strong_roots);
234
235 if (!_process_strong_tasks->is_task_claimed(SH_PS_SystemDictionary_oops_do)) {
236 SystemDictionary::roots_oops_do(strong_roots, weak_roots);
237 }
238
239 // All threads execute the following. A specific chunk of buckets
240 // from the StringTable are the individual tasks.
241 if (weak_roots != NULL) {
242 if (CollectedHeap::use_parallel_gc_threads()) {
243 StringTable::possibly_parallel_oops_do(weak_roots);
244 } else {
245 StringTable::oops_do(weak_roots);
246 }
247 }
248
249 if (!_process_strong_tasks->is_task_claimed(SH_PS_CodeCache_oops_do)) {
250 if (so & SO_ScavengeCodeCache) {
251 assert(code_roots != NULL, "must supply closure for code cache");
252
253 // We only visit parts of the CodeCache when scavenging.
254 CodeCache::scavenge_root_nmethods_do(code_roots);
255 }
256 if (so & SO_AllCodeCache) {
257 assert(code_roots != NULL, "must supply closure for code cache");
258
259 // CMSCollector uses this to do intermediate-strength collections.
260 // We scan the entire code cache, since CodeCache::do_unloading is not called.
261 CodeCache::blobs_do(code_roots);
262 }
263 // Verify that the code cache contents are not subject to
264 // movement by a scavenging collection.
265 DEBUG_ONLY(CodeBlobToOopClosure assert_code_is_non_scavengable(&assert_is_non_scavengable_closure, !CodeBlobToOopClosure::FixRelocations));
266 DEBUG_ONLY(CodeCache::asserted_non_scavengable_nmethods_do(&assert_code_is_non_scavengable));
267 }
268
269 _process_strong_tasks->all_tasks_completed();
270 }
271
272 void SharedHeap::process_all_roots(bool activate_scope,
273 ScanningOption so,
274 OopClosure* roots,
275 CLDClosure* cld_closure,
276 CodeBlobClosure* code_closure) {
277 process_roots(activate_scope, so,
278 roots, roots,
279 cld_closure, cld_closure,
280 code_closure);
281 }
282
283 void SharedHeap::process_strong_roots(bool activate_scope,
284 ScanningOption so,
285 OopClosure* roots,
286 CLDClosure* cld_closure,
287 CodeBlobClosure* code_closure) {
288 process_roots(activate_scope, so,
289 roots, NULL,
290 cld_closure, NULL,
291 code_closure);
292 }
293
294
295 class AlwaysTrueClosure: public BoolObjectClosure {
296 public:
297 bool do_object_b(oop p) { return true; }
298 };
299 static AlwaysTrueClosure always_true;
300
301 void SharedHeap::process_weak_roots(OopClosure* root_closure) {
302 // Global (weak) JNI handles
303 JNIHandles::weak_oops_do(&always_true, root_closure);
304 }
305
306 void SharedHeap::set_barrier_set(BarrierSet* bs) {
307 _barrier_set = bs;
308 // Cached barrier set for fast access in oops
309 oopDesc::set_bs(bs);
310 }
311
312 void SharedHeap::post_initialize() {
313 CollectedHeap::post_initialize();
314 ref_processing_init();
315 }
316
317 void SharedHeap::ref_processing_init() {}
318
319 // Some utilities.
320 void SharedHeap::print_size_transition(outputStream* out,
321 size_t bytes_before,
322 size_t bytes_after,
323 size_t capacity) {
324 out->print(" " SIZE_FORMAT "%s->" SIZE_FORMAT "%s(" SIZE_FORMAT "%s)",
325 byte_size_in_proper_unit(bytes_before),
326 proper_unit_for_byte_size(bytes_before),
327 byte_size_in_proper_unit(bytes_after),
328 proper_unit_for_byte_size(bytes_after),
329 byte_size_in_proper_unit(capacity),
330 proper_unit_for_byte_size(capacity));
331 }