Fri, 18 Feb 2011 10:07:34 -0800
7020042: G1: Partially remove fix for 6994628
Summary: Disable reference discovery and processing during concurrent marking by disabling fix for 6994628.
Reviewed-by: tonyp, ysr
1 /*
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3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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23 */
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/g1/g1MarkSweep.hpp"
33 #include "memory/gcLocker.hpp"
34 #include "memory/genCollectedHeap.hpp"
35 #include "memory/modRefBarrierSet.hpp"
36 #include "memory/referencePolicy.hpp"
37 #include "memory/space.hpp"
38 #include "oops/instanceRefKlass.hpp"
39 #include "oops/oop.inline.hpp"
40 #include "prims/jvmtiExport.hpp"
41 #include "runtime/aprofiler.hpp"
42 #include "runtime/biasedLocking.hpp"
43 #include "runtime/fprofiler.hpp"
44 #include "runtime/synchronizer.hpp"
45 #include "runtime/thread.hpp"
46 #include "runtime/vmThread.hpp"
47 #include "utilities/copy.hpp"
48 #include "utilities/events.hpp"
50 class HeapRegion;
52 void G1MarkSweep::invoke_at_safepoint(ReferenceProcessor* rp,
53 bool clear_all_softrefs) {
54 assert(SafepointSynchronize::is_at_safepoint(), "must be at a safepoint");
56 SharedHeap* sh = SharedHeap::heap();
57 #ifdef ASSERT
58 if (sh->collector_policy()->should_clear_all_soft_refs()) {
59 assert(clear_all_softrefs, "Policy should have been checked earler");
60 }
61 #endif
62 // hook up weak ref data so it can be used during Mark-Sweep
63 assert(GenMarkSweep::ref_processor() == NULL, "no stomping");
64 assert(rp != NULL, "should be non-NULL");
65 GenMarkSweep::_ref_processor = rp;
66 rp->setup_policy(clear_all_softrefs);
68 // When collecting the permanent generation methodOops may be moving,
69 // so we either have to flush all bcp data or convert it into bci.
70 CodeCache::gc_prologue();
71 Threads::gc_prologue();
73 // Increment the invocation count for the permanent generation, since it is
74 // implicitly collected whenever we do a full mark sweep collection.
75 sh->perm_gen()->stat_record()->invocations++;
77 bool marked_for_unloading = false;
79 allocate_stacks();
81 // We should save the marks of the currently locked biased monitors.
82 // The marking doesn't preserve the marks of biased objects.
83 BiasedLocking::preserve_marks();
85 mark_sweep_phase1(marked_for_unloading, clear_all_softrefs);
87 if (VerifyDuringGC) {
88 G1CollectedHeap* g1h = G1CollectedHeap::heap();
89 g1h->checkConcurrentMark();
90 }
92 mark_sweep_phase2();
94 // Don't add any more derived pointers during phase3
95 COMPILER2_PRESENT(DerivedPointerTable::set_active(false));
97 mark_sweep_phase3();
99 mark_sweep_phase4();
101 GenMarkSweep::restore_marks();
102 BiasedLocking::restore_marks();
103 GenMarkSweep::deallocate_stacks();
105 // We must invalidate the perm-gen rs, so that it gets rebuilt.
106 GenRemSet* rs = sh->rem_set();
107 rs->invalidate(sh->perm_gen()->used_region(), true /*whole_heap*/);
109 // "free at last gc" is calculated from these.
110 // CHF: cheating for now!!!
111 // Universe::set_heap_capacity_at_last_gc(Universe::heap()->capacity());
112 // Universe::set_heap_used_at_last_gc(Universe::heap()->used());
114 Threads::gc_epilogue();
115 CodeCache::gc_epilogue();
116 JvmtiExport::gc_epilogue();
118 // refs processing: clean slate
119 GenMarkSweep::_ref_processor = NULL;
120 }
123 void G1MarkSweep::allocate_stacks() {
124 GenMarkSweep::_preserved_count_max = 0;
125 GenMarkSweep::_preserved_marks = NULL;
126 GenMarkSweep::_preserved_count = 0;
127 }
129 void G1MarkSweep::mark_sweep_phase1(bool& marked_for_unloading,
130 bool clear_all_softrefs) {
131 // Recursively traverse all live objects and mark them
132 EventMark m("1 mark object");
133 TraceTime tm("phase 1", PrintGC && Verbose, true, gclog_or_tty);
134 GenMarkSweep::trace(" 1");
136 SharedHeap* sh = SharedHeap::heap();
138 sh->process_strong_roots(true, // activeate StrongRootsScope
139 true, // Collecting permanent generation.
140 SharedHeap::SO_SystemClasses,
141 &GenMarkSweep::follow_root_closure,
142 &GenMarkSweep::follow_code_root_closure,
143 &GenMarkSweep::follow_root_closure);
145 // Process reference objects found during marking
146 ReferenceProcessor* rp = GenMarkSweep::ref_processor();
147 rp->setup_policy(clear_all_softrefs);
148 rp->process_discovered_references(&GenMarkSweep::is_alive,
149 &GenMarkSweep::keep_alive,
150 &GenMarkSweep::follow_stack_closure,
151 NULL);
153 // Follow system dictionary roots and unload classes
154 bool purged_class = SystemDictionary::do_unloading(&GenMarkSweep::is_alive);
155 assert(GenMarkSweep::_marking_stack.is_empty(),
156 "stack should be empty by now");
158 // Follow code cache roots (has to be done after system dictionary,
159 // assumes all live klasses are marked)
160 CodeCache::do_unloading(&GenMarkSweep::is_alive,
161 &GenMarkSweep::keep_alive,
162 purged_class);
163 GenMarkSweep::follow_stack();
165 // Update subklass/sibling/implementor links of live klasses
166 GenMarkSweep::follow_weak_klass_links();
167 assert(GenMarkSweep::_marking_stack.is_empty(),
168 "stack should be empty by now");
170 // Visit memoized MDO's and clear any unmarked weak refs
171 GenMarkSweep::follow_mdo_weak_refs();
172 assert(GenMarkSweep::_marking_stack.is_empty(), "just drained");
175 // Visit interned string tables and delete unmarked oops
176 StringTable::unlink(&GenMarkSweep::is_alive);
177 // Clean up unreferenced symbols in symbol table.
178 SymbolTable::unlink();
180 assert(GenMarkSweep::_marking_stack.is_empty(),
181 "stack should be empty by now");
182 }
184 class G1PrepareCompactClosure: public HeapRegionClosure {
185 G1CollectedHeap* _g1h;
186 ModRefBarrierSet* _mrbs;
187 CompactPoint _cp;
188 HumongousRegionSet _humongous_proxy_set;
190 void free_humongous_region(HeapRegion* hr) {
191 HeapWord* end = hr->end();
192 size_t dummy_pre_used;
193 FreeRegionList dummy_free_list("Dummy Free List for G1MarkSweep");
195 assert(hr->startsHumongous(),
196 "Only the start of a humongous region should be freed.");
197 _g1h->free_humongous_region(hr, &dummy_pre_used, &dummy_free_list,
198 &_humongous_proxy_set, false /* par */);
199 hr->prepare_for_compaction(&_cp);
200 // Also clear the part of the card table that will be unused after
201 // compaction.
202 _mrbs->clear(MemRegion(hr->compaction_top(), end));
203 dummy_free_list.remove_all();
204 }
206 public:
207 G1PrepareCompactClosure(CompactibleSpace* cs)
208 : _g1h(G1CollectedHeap::heap()),
209 _mrbs(G1CollectedHeap::heap()->mr_bs()),
210 _cp(NULL, cs, cs->initialize_threshold()),
211 _humongous_proxy_set("G1MarkSweep Humongous Proxy Set") { }
213 void update_sets() {
214 // We'll recalculate total used bytes and recreate the free list
215 // at the end of the GC, so no point in updating those values here.
216 _g1h->update_sets_after_freeing_regions(0, /* pre_used */
217 NULL, /* free_list */
218 &_humongous_proxy_set,
219 false /* par */);
220 }
222 bool doHeapRegion(HeapRegion* hr) {
223 if (hr->isHumongous()) {
224 if (hr->startsHumongous()) {
225 oop obj = oop(hr->bottom());
226 if (obj->is_gc_marked()) {
227 obj->forward_to(obj);
228 } else {
229 free_humongous_region(hr);
230 }
231 } else {
232 assert(hr->continuesHumongous(), "Invalid humongous.");
233 }
234 } else {
235 hr->prepare_for_compaction(&_cp);
236 // Also clear the part of the card table that will be unused after
237 // compaction.
238 _mrbs->clear(MemRegion(hr->compaction_top(), hr->end()));
239 }
240 return false;
241 }
242 };
244 // Finds the first HeapRegion.
245 class FindFirstRegionClosure: public HeapRegionClosure {
246 HeapRegion* _a_region;
247 public:
248 FindFirstRegionClosure() : _a_region(NULL) {}
249 bool doHeapRegion(HeapRegion* r) {
250 _a_region = r;
251 return true;
252 }
253 HeapRegion* result() { return _a_region; }
254 };
256 void G1MarkSweep::mark_sweep_phase2() {
257 // Now all live objects are marked, compute the new object addresses.
259 // It is imperative that we traverse perm_gen LAST. If dead space is
260 // allowed a range of dead object may get overwritten by a dead int
261 // array. If perm_gen is not traversed last a klassOop may get
262 // overwritten. This is fine since it is dead, but if the class has dead
263 // instances we have to skip them, and in order to find their size we
264 // need the klassOop!
265 //
266 // It is not required that we traverse spaces in the same order in
267 // phase2, phase3 and phase4, but the ValidateMarkSweep live oops
268 // tracking expects us to do so. See comment under phase4.
270 G1CollectedHeap* g1h = G1CollectedHeap::heap();
271 Generation* pg = g1h->perm_gen();
273 EventMark m("2 compute new addresses");
274 TraceTime tm("phase 2", PrintGC && Verbose, true, gclog_or_tty);
275 GenMarkSweep::trace("2");
277 FindFirstRegionClosure cl;
278 g1h->heap_region_iterate(&cl);
279 HeapRegion *r = cl.result();
280 CompactibleSpace* sp = r;
281 if (r->isHumongous() && oop(r->bottom())->is_gc_marked()) {
282 sp = r->next_compaction_space();
283 }
285 G1PrepareCompactClosure blk(sp);
286 g1h->heap_region_iterate(&blk);
287 blk.update_sets();
289 CompactPoint perm_cp(pg, NULL, NULL);
290 pg->prepare_for_compaction(&perm_cp);
291 }
293 class G1AdjustPointersClosure: public HeapRegionClosure {
294 public:
295 bool doHeapRegion(HeapRegion* r) {
296 if (r->isHumongous()) {
297 if (r->startsHumongous()) {
298 // We must adjust the pointers on the single H object.
299 oop obj = oop(r->bottom());
300 debug_only(GenMarkSweep::track_interior_pointers(obj));
301 // point all the oops to the new location
302 obj->adjust_pointers();
303 debug_only(GenMarkSweep::check_interior_pointers());
304 }
305 } else {
306 // This really ought to be "as_CompactibleSpace"...
307 r->adjust_pointers();
308 }
309 return false;
310 }
311 };
313 void G1MarkSweep::mark_sweep_phase3() {
314 G1CollectedHeap* g1h = G1CollectedHeap::heap();
315 Generation* pg = g1h->perm_gen();
317 // Adjust the pointers to reflect the new locations
318 EventMark m("3 adjust pointers");
319 TraceTime tm("phase 3", PrintGC && Verbose, true, gclog_or_tty);
320 GenMarkSweep::trace("3");
322 SharedHeap* sh = SharedHeap::heap();
324 sh->process_strong_roots(true, // activate StrongRootsScope
325 true, // Collecting permanent generation.
326 SharedHeap::SO_AllClasses,
327 &GenMarkSweep::adjust_root_pointer_closure,
328 NULL, // do not touch code cache here
329 &GenMarkSweep::adjust_pointer_closure);
331 g1h->ref_processor()->weak_oops_do(&GenMarkSweep::adjust_root_pointer_closure);
333 // Now adjust pointers in remaining weak roots. (All of which should
334 // have been cleared if they pointed to non-surviving objects.)
335 g1h->g1_process_weak_roots(&GenMarkSweep::adjust_root_pointer_closure,
336 &GenMarkSweep::adjust_pointer_closure);
338 GenMarkSweep::adjust_marks();
340 G1AdjustPointersClosure blk;
341 g1h->heap_region_iterate(&blk);
342 pg->adjust_pointers();
343 }
345 class G1SpaceCompactClosure: public HeapRegionClosure {
346 public:
347 G1SpaceCompactClosure() {}
349 bool doHeapRegion(HeapRegion* hr) {
350 if (hr->isHumongous()) {
351 if (hr->startsHumongous()) {
352 oop obj = oop(hr->bottom());
353 if (obj->is_gc_marked()) {
354 obj->init_mark();
355 } else {
356 assert(hr->is_empty(), "Should have been cleared in phase 2.");
357 }
358 hr->reset_during_compaction();
359 }
360 } else {
361 hr->compact();
362 }
363 return false;
364 }
365 };
367 void G1MarkSweep::mark_sweep_phase4() {
368 // All pointers are now adjusted, move objects accordingly
370 // It is imperative that we traverse perm_gen first in phase4. All
371 // classes must be allocated earlier than their instances, and traversing
372 // perm_gen first makes sure that all klassOops have moved to their new
373 // location before any instance does a dispatch through it's klass!
375 // The ValidateMarkSweep live oops tracking expects us to traverse spaces
376 // in the same order in phase2, phase3 and phase4. We don't quite do that
377 // here (perm_gen first rather than last), so we tell the validate code
378 // to use a higher index (saved from phase2) when verifying perm_gen.
379 G1CollectedHeap* g1h = G1CollectedHeap::heap();
380 Generation* pg = g1h->perm_gen();
382 EventMark m("4 compact heap");
383 TraceTime tm("phase 4", PrintGC && Verbose, true, gclog_or_tty);
384 GenMarkSweep::trace("4");
386 pg->compact();
388 G1SpaceCompactClosure blk;
389 g1h->heap_region_iterate(&blk);
391 }
393 // Local Variables: ***
394 // c-indentation-style: gnu ***
395 // End: ***