Wed, 26 Jun 2013 16:58:37 +0200
8013590: NPG: Add a memory pool MXBean for Metaspace
Reviewed-by: jmasa, mgerdin
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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7 * published by the Free Software Foundation.
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11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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13 * accompanied this code).
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15 * You should have received a copy of the GNU General Public License version
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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/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"
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");
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
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);
72 GCTraceTime t1(GCCauseString("Full GC", gch->gc_cause()), PrintGC && !PrintGCDetails, true, NULL);
74 gch->trace_heap_before_gc(_gc_tracer);
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();
81 // Increment the invocation count
82 _total_invocations++;
84 // Capture heap size before collection for printing.
85 size_t gch_prev_used = gch->used();
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.");
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).
95 gch->save_used_regions(level);
97 allocate_stacks();
99 mark_sweep_phase1(level, clear_all_softrefs);
101 mark_sweep_phase2();
103 // Don't add any more derived pointers during phase3
104 COMPILER2_PRESENT(assert(DerivedPointerTable::is_active(), "Sanity"));
105 COMPILER2_PRESENT(DerivedPointerTable::set_active(false));
107 mark_sweep_phase3(level);
109 mark_sweep_phase4();
111 restore_marks();
113 // Set saved marks for allocation profiler (and other things? -- dld)
114 // (Should this be in general part?)
115 gch->save_marks();
117 deallocate_stacks();
119 // If compaction completely evacuated all generations younger than this
120 // one, then we can clear the card table. Otherwise, we must invalidate
121 // it (consider all cards dirty). In the future, we might consider doing
122 // compaction within generations only, and doing card-table sliding.
123 bool all_empty = true;
124 for (int i = 0; all_empty && i < level; i++) {
125 Generation* g = gch->get_gen(i);
126 all_empty = all_empty && gch->get_gen(i)->used() == 0;
127 }
128 GenRemSet* rs = gch->rem_set();
129 // Clear/invalidate below make use of the "prev_used_regions" saved earlier.
130 if (all_empty) {
131 // We've evacuated all generations below us.
132 Generation* g = gch->get_gen(level);
133 rs->clear_into_younger(g);
134 } else {
135 // Invalidate the cards corresponding to the currently used
136 // region and clear those corresponding to the evacuated region
137 // of all generations just collected (i.e. level and younger).
138 rs->invalidate_or_clear(gch->get_gen(level),
139 true /* younger */);
140 }
142 Threads::gc_epilogue();
143 CodeCache::gc_epilogue();
144 JvmtiExport::gc_epilogue();
146 if (PrintGC && !PrintGCDetails) {
147 gch->print_heap_change(gch_prev_used);
148 }
150 // refs processing: clean slate
151 _ref_processor = NULL;
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();
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);
165 gch->trace_heap_after_gc(_gc_tracer);
166 }
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);
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 }
183 _preserved_marks = (PreservedMark*)scratch;
184 _preserved_count = 0;
185 }
188 void GenMarkSweep::deallocate_stacks() {
189 if (!UseG1GC) {
190 GenCollectedHeap* gch = GenCollectedHeap::heap();
191 gch->release_scratch();
192 }
194 _preserved_mark_stack.clear(true);
195 _preserved_oop_stack.clear(true);
196 _marking_stack.clear();
197 _objarray_stack.clear(true);
198 }
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");
206 GenCollectedHeap* gch = GenCollectedHeap::heap();
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));
214 // Need new claim bits before marking starts.
215 ClassLoaderDataGraph::clear_claimed_marks();
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);
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 }
236 // This is the point where the entire marking should have completed.
237 assert(_marking_stack.is_empty(), "Marking should have completed");
239 // Unload classes and purge the SystemDictionary.
240 bool purged_class = SystemDictionary::do_unloading(&is_alive);
242 // Unload nmethods.
243 CodeCache::do_unloading(&is_alive, purged_class);
245 // Prune dead klasses from subklass/sibling/implementor lists.
246 Klass::clean_weak_klass_links(&is_alive);
248 // Delete entries for dead interned strings.
249 StringTable::unlink(&is_alive);
251 // Clean up unreferenced symbols in symbol table.
252 SymbolTable::unlink();
254 gc_tracer()->report_object_count_after_gc(&is_alive);
255 }
258 void GenMarkSweep::mark_sweep_phase2() {
259 // Now all live objects are marked, compute the new object addresses.
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.
272 GenCollectedHeap* gch = GenCollectedHeap::heap();
274 GCTraceTime tm("phase 2", PrintGC && Verbose, true, _gc_timer);
275 trace("2");
277 gch->prepare_for_compaction();
278 }
280 class GenAdjustPointersClosure: public GenCollectedHeap::GenClosure {
281 public:
282 void do_generation(Generation* gen) {
283 gen->adjust_pointers();
284 }
285 };
287 void GenMarkSweep::mark_sweep_phase3(int level) {
288 GenCollectedHeap* gch = GenCollectedHeap::heap();
290 // Adjust the pointers to reflect the new locations
291 GCTraceTime tm("phase 3", PrintGC && Verbose, true, _gc_timer);
292 trace("3");
294 // Need new claim bits for the pointer adjustment tracing.
295 ClassLoaderDataGraph::clear_claimed_marks();
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));
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);
313 // Now adjust pointers in remaining weak roots. (All of which should
314 // have been cleared if they pointed to non-surviving objects.)
315 CodeBlobToOopClosure adjust_code_pointer_closure(&adjust_pointer_closure,
316 /*do_marking=*/ false);
317 gch->gen_process_weak_roots(&adjust_pointer_closure,
318 &adjust_code_pointer_closure);
320 adjust_marks();
321 GenAdjustPointersClosure blk;
322 gch->generation_iterate(&blk, true);
323 }
325 class GenCompactClosure: public GenCollectedHeap::GenClosure {
326 public:
327 void do_generation(Generation* gen) {
328 gen->compact();
329 }
330 };
332 void GenMarkSweep::mark_sweep_phase4() {
333 // All pointers are now adjusted, move objects accordingly
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!
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();
346 GCTraceTime tm("phase 4", PrintGC && Verbose, true, _gc_timer);
347 trace("4");
349 GenCompactClosure blk;
350 gch->generation_iterate(&blk, true);
351 }