Tue, 28 May 2013 09:32:06 +0200
8013895: G1: G1SummarizeRSetStats output on Linux needs improvemen
Summary: Fixed the output of G1SummarizeRSetStats: too small datatype for the number of concurrently processed cards, added concurrent remembered set thread time retrieval for Linux and Windows (BSD uses os::elapsedTime() now), and other cleanup. The information presented during VM operation is now relative to the previous output, not always cumulative if G1SummarizeRSetStatsPeriod > 0. At VM exit, the code prints a cumulative summary.
Reviewed-by: johnc, jwilhelm
1 /*
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3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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5 * This code is free software; you can redistribute it and/or modify it
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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/g1Log.hpp"
33 #include "gc_implementation/g1/g1MarkSweep.hpp"
34 #include "memory/gcLocker.hpp"
35 #include "memory/genCollectedHeap.hpp"
36 #include "memory/modRefBarrierSet.hpp"
37 #include "memory/referencePolicy.hpp"
38 #include "memory/space.hpp"
39 #include "oops/instanceRefKlass.hpp"
40 #include "oops/oop.inline.hpp"
41 #include "prims/jvmtiExport.hpp"
42 #include "runtime/aprofiler.hpp"
43 #include "runtime/biasedLocking.hpp"
44 #include "runtime/fprofiler.hpp"
45 #include "runtime/synchronizer.hpp"
46 #include "runtime/thread.hpp"
47 #include "runtime/vmThread.hpp"
48 #include "utilities/copy.hpp"
49 #include "utilities/events.hpp"
51 class HeapRegion;
53 void G1MarkSweep::invoke_at_safepoint(ReferenceProcessor* rp,
54 bool clear_all_softrefs) {
55 assert(SafepointSynchronize::is_at_safepoint(), "must be at a safepoint");
57 SharedHeap* sh = SharedHeap::heap();
58 #ifdef ASSERT
59 if (sh->collector_policy()->should_clear_all_soft_refs()) {
60 assert(clear_all_softrefs, "Policy should have been checked earler");
61 }
62 #endif
63 // hook up weak ref data so it can be used during Mark-Sweep
64 assert(GenMarkSweep::ref_processor() == NULL, "no stomping");
65 assert(rp != NULL, "should be non-NULL");
66 assert(rp == G1CollectedHeap::heap()->ref_processor_stw(), "Precondition");
68 GenMarkSweep::_ref_processor = rp;
69 rp->setup_policy(clear_all_softrefs);
71 // When collecting the permanent generation Method*s may be moving,
72 // so we either have to flush all bcp data or convert it into bci.
73 CodeCache::gc_prologue();
74 Threads::gc_prologue();
76 bool marked_for_unloading = false;
78 allocate_stacks();
80 // We should save the marks of the currently locked biased monitors.
81 // The marking doesn't preserve the marks of biased objects.
82 BiasedLocking::preserve_marks();
84 mark_sweep_phase1(marked_for_unloading, clear_all_softrefs);
86 mark_sweep_phase2();
88 // Don't add any more derived pointers during phase3
89 COMPILER2_PRESENT(DerivedPointerTable::set_active(false));
91 mark_sweep_phase3();
93 mark_sweep_phase4();
95 GenMarkSweep::restore_marks();
96 BiasedLocking::restore_marks();
97 GenMarkSweep::deallocate_stacks();
99 // "free at last gc" is calculated from these.
100 // CHF: cheating for now!!!
101 // Universe::set_heap_capacity_at_last_gc(Universe::heap()->capacity());
102 // Universe::set_heap_used_at_last_gc(Universe::heap()->used());
104 Threads::gc_epilogue();
105 CodeCache::gc_epilogue();
106 JvmtiExport::gc_epilogue();
108 // refs processing: clean slate
109 GenMarkSweep::_ref_processor = NULL;
110 }
113 void G1MarkSweep::allocate_stacks() {
114 GenMarkSweep::_preserved_count_max = 0;
115 GenMarkSweep::_preserved_marks = NULL;
116 GenMarkSweep::_preserved_count = 0;
117 }
119 void G1MarkSweep::mark_sweep_phase1(bool& marked_for_unloading,
120 bool clear_all_softrefs) {
121 // Recursively traverse all live objects and mark them
122 TraceTime tm("phase 1", G1Log::fine() && Verbose, true, gclog_or_tty);
123 GenMarkSweep::trace(" 1");
125 SharedHeap* sh = SharedHeap::heap();
127 // Need cleared claim bits for the strong roots processing
128 ClassLoaderDataGraph::clear_claimed_marks();
130 sh->process_strong_roots(true, // activate StrongRootsScope
131 false, // not scavenging.
132 SharedHeap::SO_SystemClasses,
133 &GenMarkSweep::follow_root_closure,
134 &GenMarkSweep::follow_code_root_closure,
135 &GenMarkSweep::follow_klass_closure);
137 // Process reference objects found during marking
138 ReferenceProcessor* rp = GenMarkSweep::ref_processor();
139 assert(rp == G1CollectedHeap::heap()->ref_processor_stw(), "Sanity");
141 rp->setup_policy(clear_all_softrefs);
142 rp->process_discovered_references(&GenMarkSweep::is_alive,
143 &GenMarkSweep::keep_alive,
144 &GenMarkSweep::follow_stack_closure,
145 NULL);
148 // This is the point where the entire marking should have completed.
149 assert(GenMarkSweep::_marking_stack.is_empty(), "Marking should have completed");
151 // Unload classes and purge the SystemDictionary.
152 bool purged_class = SystemDictionary::do_unloading(&GenMarkSweep::is_alive);
154 // Unload nmethods.
155 CodeCache::do_unloading(&GenMarkSweep::is_alive, purged_class);
157 // Prune dead klasses from subklass/sibling/implementor lists.
158 Klass::clean_weak_klass_links(&GenMarkSweep::is_alive);
160 // Delete entries for dead interned strings.
161 StringTable::unlink(&GenMarkSweep::is_alive);
163 // Clean up unreferenced symbols in symbol table.
164 SymbolTable::unlink();
166 if (VerifyDuringGC) {
167 HandleMark hm; // handle scope
168 COMPILER2_PRESENT(DerivedPointerTableDeactivate dpt_deact);
169 Universe::heap()->prepare_for_verify();
170 // Note: we can verify only the heap here. When an object is
171 // marked, the previous value of the mark word (including
172 // identity hash values, ages, etc) is preserved, and the mark
173 // word is set to markOop::marked_value - effectively removing
174 // any hash values from the mark word. These hash values are
175 // used when verifying the dictionaries and so removing them
176 // from the mark word can make verification of the dictionaries
177 // fail. At the end of the GC, the orginal mark word values
178 // (including hash values) are restored to the appropriate
179 // objects.
180 if (!VerifySilently) {
181 gclog_or_tty->print(" VerifyDuringGC:(full)[Verifying ");
182 }
183 Universe::heap()->verify(VerifySilently, VerifyOption_G1UseMarkWord);
184 if (!VerifySilently) {
185 gclog_or_tty->print_cr("]");
186 }
187 }
188 }
190 class G1PrepareCompactClosure: public HeapRegionClosure {
191 G1CollectedHeap* _g1h;
192 ModRefBarrierSet* _mrbs;
193 CompactPoint _cp;
194 HumongousRegionSet _humongous_proxy_set;
196 void free_humongous_region(HeapRegion* hr) {
197 HeapWord* end = hr->end();
198 size_t dummy_pre_used;
199 FreeRegionList dummy_free_list("Dummy Free List for G1MarkSweep");
201 assert(hr->startsHumongous(),
202 "Only the start of a humongous region should be freed.");
203 _g1h->free_humongous_region(hr, &dummy_pre_used, &dummy_free_list,
204 &_humongous_proxy_set, false /* par */);
205 hr->prepare_for_compaction(&_cp);
206 // Also clear the part of the card table that will be unused after
207 // compaction.
208 _mrbs->clear(MemRegion(hr->compaction_top(), end));
209 dummy_free_list.remove_all();
210 }
212 public:
213 G1PrepareCompactClosure(CompactibleSpace* cs)
214 : _g1h(G1CollectedHeap::heap()),
215 _mrbs(G1CollectedHeap::heap()->mr_bs()),
216 _cp(NULL, cs, cs->initialize_threshold()),
217 _humongous_proxy_set("G1MarkSweep Humongous Proxy Set") { }
219 void update_sets() {
220 // We'll recalculate total used bytes and recreate the free list
221 // at the end of the GC, so no point in updating those values here.
222 _g1h->update_sets_after_freeing_regions(0, /* pre_used */
223 NULL, /* free_list */
224 NULL, /* old_proxy_set */
225 &_humongous_proxy_set,
226 false /* par */);
227 }
229 bool doHeapRegion(HeapRegion* hr) {
230 if (hr->isHumongous()) {
231 if (hr->startsHumongous()) {
232 oop obj = oop(hr->bottom());
233 if (obj->is_gc_marked()) {
234 obj->forward_to(obj);
235 } else {
236 free_humongous_region(hr);
237 }
238 } else {
239 assert(hr->continuesHumongous(), "Invalid humongous.");
240 }
241 } else {
242 hr->prepare_for_compaction(&_cp);
243 // Also clear the part of the card table that will be unused after
244 // compaction.
245 _mrbs->clear(MemRegion(hr->compaction_top(), hr->end()));
246 }
247 return false;
248 }
249 };
251 void G1MarkSweep::mark_sweep_phase2() {
252 // Now all live objects are marked, compute the new object addresses.
254 // It is not required that we traverse spaces in the same order in
255 // phase2, phase3 and phase4, but the ValidateMarkSweep live oops
256 // tracking expects us to do so. See comment under phase4.
258 G1CollectedHeap* g1h = G1CollectedHeap::heap();
260 TraceTime tm("phase 2", G1Log::fine() && Verbose, true, gclog_or_tty);
261 GenMarkSweep::trace("2");
263 // find the first region
264 HeapRegion* r = g1h->region_at(0);
265 CompactibleSpace* sp = r;
266 if (r->isHumongous() && oop(r->bottom())->is_gc_marked()) {
267 sp = r->next_compaction_space();
268 }
270 G1PrepareCompactClosure blk(sp);
271 g1h->heap_region_iterate(&blk);
272 blk.update_sets();
273 }
275 class G1AdjustPointersClosure: public HeapRegionClosure {
276 public:
277 bool doHeapRegion(HeapRegion* r) {
278 if (r->isHumongous()) {
279 if (r->startsHumongous()) {
280 // We must adjust the pointers on the single H object.
281 oop obj = oop(r->bottom());
282 // point all the oops to the new location
283 obj->adjust_pointers();
284 }
285 } else {
286 // This really ought to be "as_CompactibleSpace"...
287 r->adjust_pointers();
288 }
289 return false;
290 }
291 };
293 void G1MarkSweep::mark_sweep_phase3() {
294 G1CollectedHeap* g1h = G1CollectedHeap::heap();
296 // Adjust the pointers to reflect the new locations
297 TraceTime tm("phase 3", G1Log::fine() && Verbose, true, gclog_or_tty);
298 GenMarkSweep::trace("3");
300 SharedHeap* sh = SharedHeap::heap();
302 // Need cleared claim bits for the strong roots processing
303 ClassLoaderDataGraph::clear_claimed_marks();
305 sh->process_strong_roots(true, // activate StrongRootsScope
306 false, // not scavenging.
307 SharedHeap::SO_AllClasses,
308 &GenMarkSweep::adjust_pointer_closure,
309 NULL, // do not touch code cache here
310 &GenMarkSweep::adjust_klass_closure);
312 assert(GenMarkSweep::ref_processor() == g1h->ref_processor_stw(), "Sanity");
313 g1h->ref_processor_stw()->weak_oops_do(&GenMarkSweep::adjust_pointer_closure);
315 // Now adjust pointers in remaining weak roots. (All of which should
316 // have been cleared if they pointed to non-surviving objects.)
317 g1h->g1_process_weak_roots(&GenMarkSweep::adjust_pointer_closure);
319 GenMarkSweep::adjust_marks();
321 G1AdjustPointersClosure blk;
322 g1h->heap_region_iterate(&blk);
323 }
325 class G1SpaceCompactClosure: public HeapRegionClosure {
326 public:
327 G1SpaceCompactClosure() {}
329 bool doHeapRegion(HeapRegion* hr) {
330 if (hr->isHumongous()) {
331 if (hr->startsHumongous()) {
332 oop obj = oop(hr->bottom());
333 if (obj->is_gc_marked()) {
334 obj->init_mark();
335 } else {
336 assert(hr->is_empty(), "Should have been cleared in phase 2.");
337 }
338 hr->reset_during_compaction();
339 }
340 } else {
341 hr->compact();
342 }
343 return false;
344 }
345 };
347 void G1MarkSweep::mark_sweep_phase4() {
348 // All pointers are now adjusted, move objects accordingly
350 // The ValidateMarkSweep live oops tracking expects us to traverse spaces
351 // in the same order in phase2, phase3 and phase4. We don't quite do that
352 // here (code and comment not fixed for perm removal), so we tell the validate code
353 // to use a higher index (saved from phase2) when verifying perm_gen.
354 G1CollectedHeap* g1h = G1CollectedHeap::heap();
356 TraceTime tm("phase 4", G1Log::fine() && Verbose, true, gclog_or_tty);
357 GenMarkSweep::trace("4");
359 G1SpaceCompactClosure blk;
360 g1h->heap_region_iterate(&blk);
362 }