1 /*
2 * Copyright (c) 2001, 2012, 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/javaClasses.hpp"
27 #include "classfile/symbolTable.hpp"
28 #include "classfile/systemDictionary.hpp"
29 #include "classfile/vmSymbols.hpp"
30 #include "code/codeCache.hpp"
31 #include "code/icBuffer.hpp"
32 #include "gc_interface/collectedHeap.inline.hpp"
33 #include "memory/genCollectedHeap.hpp"
34 #include "memory/genMarkSweep.hpp"
35 #include "memory/genOopClosures.inline.hpp"
36 #include "memory/generation.inline.hpp"
37 #include "memory/modRefBarrierSet.hpp"
38 #include "memory/referencePolicy.hpp"
39 #include "memory/space.hpp"
40 #include "oops/instanceRefKlass.hpp"
41 #include "oops/oop.inline.hpp"
42 #include "prims/jvmtiExport.hpp"
43 #include "runtime/fprofiler.hpp"
44 #include "runtime/handles.inline.hpp"
45 #include "runtime/synchronizer.hpp"
46 #include "runtime/thread.inline.hpp"
47 #include "runtime/vmThread.hpp"
48 #include "utilities/copy.hpp"
49 #include "utilities/events.hpp"
50
51 void GenMarkSweep::invoke_at_safepoint(int level, ReferenceProcessor* rp,
52 bool clear_all_softrefs) {
53 assert(SafepointSynchronize::is_at_safepoint(), "must be at a safepoint");
54
55 GenCollectedHeap* gch = GenCollectedHeap::heap();
56 #ifdef ASSERT
57 if (gch->collector_policy()->should_clear_all_soft_refs()) {
58 assert(clear_all_softrefs, "Policy should have been checked earlier");
59 }
60 #endif
61
62 // hook up weak ref data so it can be used during Mark-Sweep
63 assert(ref_processor() == NULL, "no stomping");
64 assert(rp != NULL, "should be non-NULL");
65 _ref_processor = rp;
66 rp->setup_policy(clear_all_softrefs);
67
68 TraceTime t1(GCCauseString("Full GC", gch->gc_cause()), PrintGC && !PrintGCDetails, true, gclog_or_tty);
69
70 // When collecting the permanent generation Method*s may be moving,
71 // so we either have to flush all bcp data or convert it into bci.
72 CodeCache::gc_prologue();
73 Threads::gc_prologue();
74
75 // Increment the invocation count
76 _total_invocations++;
77
78 // Capture heap size before collection for printing.
79 size_t gch_prev_used = gch->used();
80
81 // Some of the card table updates below assume that the perm gen is
82 // also being collected.
83 assert(level == gch->n_gens() - 1,
84 "All generations are being collected, ergo perm gen too.");
85
86 // Capture used regions for each generation that will be
87 // subject to collection, so that card table adjustments can
88 // be made intelligently (see clear / invalidate further below).
138 JvmtiExport::gc_epilogue();
139
140 if (PrintGC && !PrintGCDetails) {
141 gch->print_heap_change(gch_prev_used);
142 }
143
144 // refs processing: clean slate
145 _ref_processor = NULL;
146
147 // Update heap occupancy information which is used as
148 // input to soft ref clearing policy at the next gc.
149 Universe::update_heap_info_at_gc();
150
151 // Update time of last gc for all generations we collected
152 // (which curently is all the generations in the heap).
153 // We need to use a monotonically non-deccreasing time in ms
154 // or we will see time-warp warnings and os::javaTimeMillis()
155 // does not guarantee monotonicity.
156 jlong now = os::javaTimeNanos() / NANOSECS_PER_MILLISEC;
157 gch->update_time_of_last_gc(now);
158 }
159
160 void GenMarkSweep::allocate_stacks() {
161 GenCollectedHeap* gch = GenCollectedHeap::heap();
162 // Scratch request on behalf of oldest generation; will do no
163 // allocation.
164 ScratchBlock* scratch = gch->gather_scratch(gch->_gens[gch->_n_gens-1], 0);
165
166 // $$$ To cut a corner, we'll only use the first scratch block, and then
167 // revert to malloc.
168 if (scratch != NULL) {
169 _preserved_count_max =
170 scratch->num_words * HeapWordSize / sizeof(PreservedMark);
171 } else {
172 _preserved_count_max = 0;
173 }
174
175 _preserved_marks = (PreservedMark*)scratch;
176 _preserved_count = 0;
177 }
178
179
180 void GenMarkSweep::deallocate_stacks() {
181 if (!UseG1GC) {
182 GenCollectedHeap* gch = GenCollectedHeap::heap();
183 gch->release_scratch();
184 }
185
186 _preserved_mark_stack.clear(true);
187 _preserved_oop_stack.clear(true);
188 _marking_stack.clear();
189 _objarray_stack.clear(true);
190 }
191
192 void GenMarkSweep::mark_sweep_phase1(int level,
193 bool clear_all_softrefs) {
194 // Recursively traverse all live objects and mark them
195 TraceTime tm("phase 1", PrintGC && Verbose, true, gclog_or_tty);
196 trace(" 1");
197
198 GenCollectedHeap* gch = GenCollectedHeap::heap();
199
200 // Because follow_root_closure is created statically, cannot
201 // use OopsInGenClosure constructor which takes a generation,
202 // as the Universe has not been created when the static constructors
203 // are run.
204 follow_root_closure.set_orig_generation(gch->get_gen(level));
205
206 // Need new claim bits before marking starts.
207 ClassLoaderDataGraph::clear_claimed_marks();
208
209 gch->gen_process_strong_roots(level,
210 false, // Younger gens are not roots.
211 true, // activate StrongRootsScope
212 false, // not scavenging
213 SharedHeap::SO_SystemClasses,
214 &follow_root_closure,
215 true, // walk code active on stacks
216 &follow_root_closure,
217 &follow_klass_closure);
218
219 // Process reference objects found during marking
220 {
221 ref_processor()->setup_policy(clear_all_softrefs);
222 ref_processor()->process_discovered_references(
223 &is_alive, &keep_alive, &follow_stack_closure, NULL);
224 }
225
226 // This is the point where the entire marking should have completed.
227 assert(_marking_stack.is_empty(), "Marking should have completed");
228
229 // Unload classes and purge the SystemDictionary.
230 bool purged_class = SystemDictionary::do_unloading(&is_alive);
231
232 // Unload nmethods.
233 CodeCache::do_unloading(&is_alive, purged_class);
234
235 // Prune dead klasses from subklass/sibling/implementor lists.
236 Klass::clean_weak_klass_links(&is_alive);
237
238 // Delete entries for dead interned strings.
239 StringTable::unlink(&is_alive);
240
241 // Clean up unreferenced symbols in symbol table.
242 SymbolTable::unlink();
243 }
244
245
246 void GenMarkSweep::mark_sweep_phase2() {
247 // Now all live objects are marked, compute the new object addresses.
248
249 // It is imperative that we traverse perm_gen LAST. If dead space is
250 // allowed a range of dead object may get overwritten by a dead int
251 // array. If perm_gen is not traversed last a Klass* may get
252 // overwritten. This is fine since it is dead, but if the class has dead
253 // instances we have to skip them, and in order to find their size we
254 // need the Klass*!
255 //
256 // It is not required that we traverse spaces in the same order in
257 // phase2, phase3 and phase4, but the ValidateMarkSweep live oops
258 // tracking expects us to do so. See comment under phase4.
259
260 GenCollectedHeap* gch = GenCollectedHeap::heap();
261
262 TraceTime tm("phase 2", PrintGC && Verbose, true, gclog_or_tty);
263 trace("2");
264
265 gch->prepare_for_compaction();
266 }
267
268 class GenAdjustPointersClosure: public GenCollectedHeap::GenClosure {
269 public:
270 void do_generation(Generation* gen) {
271 gen->adjust_pointers();
272 }
273 };
274
275 void GenMarkSweep::mark_sweep_phase3(int level) {
276 GenCollectedHeap* gch = GenCollectedHeap::heap();
277
278 // Adjust the pointers to reflect the new locations
279 TraceTime tm("phase 3", PrintGC && Verbose, true, gclog_or_tty);
280 trace("3");
281
282 // Need new claim bits for the pointer adjustment tracing.
283 ClassLoaderDataGraph::clear_claimed_marks();
284
285 // Because the closure below is created statically, we cannot
286 // use OopsInGenClosure constructor which takes a generation,
287 // as the Universe has not been created when the static constructors
288 // are run.
289 adjust_pointer_closure.set_orig_generation(gch->get_gen(level));
290
291 gch->gen_process_strong_roots(level,
292 false, // Younger gens are not roots.
293 true, // activate StrongRootsScope
294 false, // not scavenging
295 SharedHeap::SO_AllClasses,
296 &adjust_pointer_closure,
297 false, // do not walk code
298 &adjust_pointer_closure,
299 &adjust_klass_closure);
314 public:
315 void do_generation(Generation* gen) {
316 gen->compact();
317 }
318 };
319
320 void GenMarkSweep::mark_sweep_phase4() {
321 // All pointers are now adjusted, move objects accordingly
322
323 // It is imperative that we traverse perm_gen first in phase4. All
324 // classes must be allocated earlier than their instances, and traversing
325 // perm_gen first makes sure that all Klass*s have moved to their new
326 // location before any instance does a dispatch through it's klass!
327
328 // The ValidateMarkSweep live oops tracking expects us to traverse spaces
329 // in the same order in phase2, phase3 and phase4. We don't quite do that
330 // here (perm_gen first rather than last), so we tell the validate code
331 // to use a higher index (saved from phase2) when verifying perm_gen.
332 GenCollectedHeap* gch = GenCollectedHeap::heap();
333
334 TraceTime tm("phase 4", PrintGC && Verbose, true, gclog_or_tty);
335 trace("4");
336
337 GenCompactClosure blk;
338 gch->generation_iterate(&blk, true);
339 }
|
1 /*
2 * Copyright (c) 2001, 2013, 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/javaClasses.hpp"
27 #include "classfile/symbolTable.hpp"
28 #include "classfile/systemDictionary.hpp"
29 #include "classfile/vmSymbols.hpp"
30 #include "code/codeCache.hpp"
31 #include "code/icBuffer.hpp"
32 #include "gc_implementation/shared/gcHeapSummary.hpp"
33 #include "gc_implementation/shared/gcTimer.hpp"
34 #include "gc_implementation/shared/gcTrace.hpp"
35 #include "gc_implementation/shared/gcTraceTime.hpp"
36 #include "gc_interface/collectedHeap.inline.hpp"
37 #include "memory/genCollectedHeap.hpp"
38 #include "memory/genMarkSweep.hpp"
39 #include "memory/genOopClosures.inline.hpp"
40 #include "memory/generation.inline.hpp"
41 #include "memory/modRefBarrierSet.hpp"
42 #include "memory/referencePolicy.hpp"
43 #include "memory/space.hpp"
44 #include "oops/instanceRefKlass.hpp"
45 #include "oops/oop.inline.hpp"
46 #include "prims/jvmtiExport.hpp"
47 #include "runtime/fprofiler.hpp"
48 #include "runtime/handles.inline.hpp"
49 #include "runtime/synchronizer.hpp"
50 #include "runtime/thread.inline.hpp"
51 #include "runtime/vmThread.hpp"
52 #include "utilities/copy.hpp"
53 #include "utilities/events.hpp"
54
55 void GenMarkSweep::invoke_at_safepoint(int level, ReferenceProcessor* rp,
56 bool clear_all_softrefs) {
57 assert(SafepointSynchronize::is_at_safepoint(), "must be at a safepoint");
58
59 GenCollectedHeap* gch = GenCollectedHeap::heap();
60 #ifdef ASSERT
61 if (gch->collector_policy()->should_clear_all_soft_refs()) {
62 assert(clear_all_softrefs, "Policy should have been checked earlier");
63 }
64 #endif
65
66 // hook up weak ref data so it can be used during Mark-Sweep
67 assert(ref_processor() == NULL, "no stomping");
68 assert(rp != NULL, "should be non-NULL");
69 _ref_processor = rp;
70 rp->setup_policy(clear_all_softrefs);
71
72 GCTraceTime t1(GCCauseString("Full GC", gch->gc_cause()), PrintGC && !PrintGCDetails, true, NULL);
73
74 gch->trace_heap_before_gc(_gc_tracer);
75
76 // When collecting the permanent generation Method*s may be moving,
77 // so we either have to flush all bcp data or convert it into bci.
78 CodeCache::gc_prologue();
79 Threads::gc_prologue();
80
81 // Increment the invocation count
82 _total_invocations++;
83
84 // Capture heap size before collection for printing.
85 size_t gch_prev_used = gch->used();
86
87 // Some of the card table updates below assume that the perm gen is
88 // also being collected.
89 assert(level == gch->n_gens() - 1,
90 "All generations are being collected, ergo perm gen too.");
91
92 // Capture used regions for each generation that will be
93 // subject to collection, so that card table adjustments can
94 // be made intelligently (see clear / invalidate further below).
144 JvmtiExport::gc_epilogue();
145
146 if (PrintGC && !PrintGCDetails) {
147 gch->print_heap_change(gch_prev_used);
148 }
149
150 // refs processing: clean slate
151 _ref_processor = NULL;
152
153 // Update heap occupancy information which is used as
154 // input to soft ref clearing policy at the next gc.
155 Universe::update_heap_info_at_gc();
156
157 // Update time of last gc for all generations we collected
158 // (which curently is all the generations in the heap).
159 // We need to use a monotonically non-deccreasing time in ms
160 // or we will see time-warp warnings and os::javaTimeMillis()
161 // does not guarantee monotonicity.
162 jlong now = os::javaTimeNanos() / NANOSECS_PER_MILLISEC;
163 gch->update_time_of_last_gc(now);
164
165 gch->trace_heap_after_gc(_gc_tracer);
166 }
167
168 void GenMarkSweep::allocate_stacks() {
169 GenCollectedHeap* gch = GenCollectedHeap::heap();
170 // Scratch request on behalf of oldest generation; will do no
171 // allocation.
172 ScratchBlock* scratch = gch->gather_scratch(gch->_gens[gch->_n_gens-1], 0);
173
174 // $$$ To cut a corner, we'll only use the first scratch block, and then
175 // revert to malloc.
176 if (scratch != NULL) {
177 _preserved_count_max =
178 scratch->num_words * HeapWordSize / sizeof(PreservedMark);
179 } else {
180 _preserved_count_max = 0;
181 }
182
183 _preserved_marks = (PreservedMark*)scratch;
184 _preserved_count = 0;
185 }
186
187
188 void GenMarkSweep::deallocate_stacks() {
189 if (!UseG1GC) {
190 GenCollectedHeap* gch = GenCollectedHeap::heap();
191 gch->release_scratch();
192 }
193
194 _preserved_mark_stack.clear(true);
195 _preserved_oop_stack.clear(true);
196 _marking_stack.clear();
197 _objarray_stack.clear(true);
198 }
199
200 void GenMarkSweep::mark_sweep_phase1(int level,
201 bool clear_all_softrefs) {
202 // Recursively traverse all live objects and mark them
203 GCTraceTime tm("phase 1", PrintGC && Verbose, true, _gc_timer);
204 trace(" 1");
205
206 GenCollectedHeap* gch = GenCollectedHeap::heap();
207
208 // Because follow_root_closure is created statically, cannot
209 // use OopsInGenClosure constructor which takes a generation,
210 // as the Universe has not been created when the static constructors
211 // are run.
212 follow_root_closure.set_orig_generation(gch->get_gen(level));
213
214 // Need new claim bits before marking starts.
215 ClassLoaderDataGraph::clear_claimed_marks();
216
217 gch->gen_process_strong_roots(level,
218 false, // Younger gens are not roots.
219 true, // activate StrongRootsScope
220 false, // not scavenging
221 SharedHeap::SO_SystemClasses,
222 &follow_root_closure,
223 true, // walk code active on stacks
224 &follow_root_closure,
225 &follow_klass_closure);
226
227 // Process reference objects found during marking
228 {
229 ref_processor()->setup_policy(clear_all_softrefs);
230 const ReferenceProcessorStats& stats =
231 ref_processor()->process_discovered_references(
232 &is_alive, &keep_alive, &follow_stack_closure, NULL, _gc_timer);
233 gc_tracer()->report_gc_reference_stats(stats);
234 }
235
236 // This is the point where the entire marking should have completed.
237 assert(_marking_stack.is_empty(), "Marking should have completed");
238
239 // Unload classes and purge the SystemDictionary.
240 bool purged_class = SystemDictionary::do_unloading(&is_alive);
241
242 // Unload nmethods.
243 CodeCache::do_unloading(&is_alive, purged_class);
244
245 // Prune dead klasses from subklass/sibling/implementor lists.
246 Klass::clean_weak_klass_links(&is_alive);
247
248 // Delete entries for dead interned strings.
249 StringTable::unlink(&is_alive);
250
251 // Clean up unreferenced symbols in symbol table.
252 SymbolTable::unlink();
253
254 gc_tracer()->report_object_count_after_gc(&is_alive);
255 }
256
257
258 void GenMarkSweep::mark_sweep_phase2() {
259 // Now all live objects are marked, compute the new object addresses.
260
261 // It is imperative that we traverse perm_gen LAST. If dead space is
262 // allowed a range of dead object may get overwritten by a dead int
263 // array. If perm_gen is not traversed last a Klass* may get
264 // overwritten. This is fine since it is dead, but if the class has dead
265 // instances we have to skip them, and in order to find their size we
266 // need the Klass*!
267 //
268 // It is not required that we traverse spaces in the same order in
269 // phase2, phase3 and phase4, but the ValidateMarkSweep live oops
270 // tracking expects us to do so. See comment under phase4.
271
272 GenCollectedHeap* gch = GenCollectedHeap::heap();
273
274 GCTraceTime tm("phase 2", PrintGC && Verbose, true, _gc_timer);
275 trace("2");
276
277 gch->prepare_for_compaction();
278 }
279
280 class GenAdjustPointersClosure: public GenCollectedHeap::GenClosure {
281 public:
282 void do_generation(Generation* gen) {
283 gen->adjust_pointers();
284 }
285 };
286
287 void GenMarkSweep::mark_sweep_phase3(int level) {
288 GenCollectedHeap* gch = GenCollectedHeap::heap();
289
290 // Adjust the pointers to reflect the new locations
291 GCTraceTime tm("phase 3", PrintGC && Verbose, true, _gc_timer);
292 trace("3");
293
294 // Need new claim bits for the pointer adjustment tracing.
295 ClassLoaderDataGraph::clear_claimed_marks();
296
297 // Because the closure below is created statically, we cannot
298 // use OopsInGenClosure constructor which takes a generation,
299 // as the Universe has not been created when the static constructors
300 // are run.
301 adjust_pointer_closure.set_orig_generation(gch->get_gen(level));
302
303 gch->gen_process_strong_roots(level,
304 false, // Younger gens are not roots.
305 true, // activate StrongRootsScope
306 false, // not scavenging
307 SharedHeap::SO_AllClasses,
308 &adjust_pointer_closure,
309 false, // do not walk code
310 &adjust_pointer_closure,
311 &adjust_klass_closure);
326 public:
327 void do_generation(Generation* gen) {
328 gen->compact();
329 }
330 };
331
332 void GenMarkSweep::mark_sweep_phase4() {
333 // All pointers are now adjusted, move objects accordingly
334
335 // It is imperative that we traverse perm_gen first in phase4. All
336 // classes must be allocated earlier than their instances, and traversing
337 // perm_gen first makes sure that all Klass*s have moved to their new
338 // location before any instance does a dispatch through it's klass!
339
340 // The ValidateMarkSweep live oops tracking expects us to traverse spaces
341 // in the same order in phase2, phase3 and phase4. We don't quite do that
342 // here (perm_gen first rather than last), so we tell the validate code
343 // to use a higher index (saved from phase2) when verifying perm_gen.
344 GenCollectedHeap* gch = GenCollectedHeap::heap();
345
346 GCTraceTime tm("phase 4", PrintGC && Verbose, true, _gc_timer);
347 trace("4");
348
349 GenCompactClosure blk;
350 gch->generation_iterate(&blk, true);
351 }
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