Wed, 03 Jul 2013 17:26:59 -0400
7133260: AllocationProfiler uses space in metadata and doesn't seem to do anything useful.
Summary: Remove -Xaprof and Klass::_alloc_count & ArrayKlass::_alloc_size.
Reviewed-by: stefank, coleenp
1 /*
2 * Copyright (c) 2000, 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.
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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).
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23 */
25 #ifndef SHARE_VM_MEMORY_GENCOLLECTEDHEAP_HPP
26 #define SHARE_VM_MEMORY_GENCOLLECTEDHEAP_HPP
28 #include "gc_implementation/shared/adaptiveSizePolicy.hpp"
29 #include "memory/collectorPolicy.hpp"
30 #include "memory/generation.hpp"
31 #include "memory/sharedHeap.hpp"
33 class SubTasksDone;
35 // A "GenCollectedHeap" is a SharedHeap that uses generational
36 // collection. It is represented with a sequence of Generation's.
37 class GenCollectedHeap : public SharedHeap {
38 friend class GenCollectorPolicy;
39 friend class Generation;
40 friend class DefNewGeneration;
41 friend class TenuredGeneration;
42 friend class ConcurrentMarkSweepGeneration;
43 friend class CMSCollector;
44 friend class GenMarkSweep;
45 friend class VM_GenCollectForAllocation;
46 friend class VM_GenCollectFull;
47 friend class VM_GenCollectFullConcurrent;
48 friend class VM_GC_HeapInspection;
49 friend class VM_HeapDumper;
50 friend class HeapInspection;
51 friend class GCCauseSetter;
52 friend class VMStructs;
53 public:
54 enum SomeConstants {
55 max_gens = 10
56 };
58 friend class VM_PopulateDumpSharedSpace;
60 protected:
61 // Fields:
62 static GenCollectedHeap* _gch;
64 private:
65 int _n_gens;
66 Generation* _gens[max_gens];
67 GenerationSpec** _gen_specs;
69 // The generational collector policy.
70 GenCollectorPolicy* _gen_policy;
72 // Indicates that the most recent previous incremental collection failed.
73 // The flag is cleared when an action is taken that might clear the
74 // condition that caused that incremental collection to fail.
75 bool _incremental_collection_failed;
77 // In support of ExplicitGCInvokesConcurrent functionality
78 unsigned int _full_collections_completed;
80 // Data structure for claiming the (potentially) parallel tasks in
81 // (gen-specific) strong roots processing.
82 SubTasksDone* _gen_process_strong_tasks;
83 SubTasksDone* gen_process_strong_tasks() { return _gen_process_strong_tasks; }
85 // In block contents verification, the number of header words to skip
86 NOT_PRODUCT(static size_t _skip_header_HeapWords;)
88 protected:
89 // Directs each generation up to and including "collectedGen" to recompute
90 // its desired size.
91 void compute_new_generation_sizes(int collectedGen);
93 // Helper functions for allocation
94 HeapWord* attempt_allocation(size_t size,
95 bool is_tlab,
96 bool first_only);
98 // Helper function for two callbacks below.
99 // Considers collection of the first max_level+1 generations.
100 void do_collection(bool full,
101 bool clear_all_soft_refs,
102 size_t size,
103 bool is_tlab,
104 int max_level);
106 // Callback from VM_GenCollectForAllocation operation.
107 // This function does everything necessary/possible to satisfy an
108 // allocation request that failed in the youngest generation that should
109 // have handled it (including collection, expansion, etc.)
110 HeapWord* satisfy_failed_allocation(size_t size, bool is_tlab);
112 // Callback from VM_GenCollectFull operation.
113 // Perform a full collection of the first max_level+1 generations.
114 virtual void do_full_collection(bool clear_all_soft_refs);
115 void do_full_collection(bool clear_all_soft_refs, int max_level);
117 // Does the "cause" of GC indicate that
118 // we absolutely __must__ clear soft refs?
119 bool must_clear_all_soft_refs();
121 public:
122 GenCollectedHeap(GenCollectorPolicy *policy);
124 GCStats* gc_stats(int level) const;
126 // Returns JNI_OK on success
127 virtual jint initialize();
128 char* allocate(size_t alignment,
129 size_t* _total_reserved, int* _n_covered_regions,
130 ReservedSpace* heap_rs);
132 // Does operations required after initialization has been done.
133 void post_initialize();
135 // Initialize ("weak") refs processing support
136 virtual void ref_processing_init();
138 virtual CollectedHeap::Name kind() const {
139 return CollectedHeap::GenCollectedHeap;
140 }
142 // The generational collector policy.
143 GenCollectorPolicy* gen_policy() const { return _gen_policy; }
144 virtual CollectorPolicy* collector_policy() const { return (CollectorPolicy*) gen_policy(); }
146 // Adaptive size policy
147 virtual AdaptiveSizePolicy* size_policy() {
148 return gen_policy()->size_policy();
149 }
151 size_t capacity() const;
152 size_t used() const;
154 // Save the "used_region" for generations level and lower.
155 void save_used_regions(int level);
157 size_t max_capacity() const;
159 HeapWord* mem_allocate(size_t size,
160 bool* gc_overhead_limit_was_exceeded);
162 // We may support a shared contiguous allocation area, if the youngest
163 // generation does.
164 bool supports_inline_contig_alloc() const;
165 HeapWord** top_addr() const;
166 HeapWord** end_addr() const;
168 // Return an estimate of the maximum allocation that could be performed
169 // without triggering any collection activity. In a generational
170 // collector, for example, this is probably the largest allocation that
171 // could be supported in the youngest generation. It is "unsafe" because
172 // no locks are taken; the result should be treated as an approximation,
173 // not a guarantee.
174 size_t unsafe_max_alloc();
176 // Does this heap support heap inspection? (+PrintClassHistogram)
177 virtual bool supports_heap_inspection() const { return true; }
179 // Perform a full collection of the heap; intended for use in implementing
180 // "System.gc". This implies as full a collection as the CollectedHeap
181 // supports. Caller does not hold the Heap_lock on entry.
182 void collect(GCCause::Cause cause);
184 // The same as above but assume that the caller holds the Heap_lock.
185 void collect_locked(GCCause::Cause cause);
187 // Perform a full collection of the first max_level+1 generations.
188 // Mostly used for testing purposes. Caller does not hold the Heap_lock on entry.
189 void collect(GCCause::Cause cause, int max_level);
191 // Returns "TRUE" iff "p" points into the committed areas of the heap.
192 // The methods is_in(), is_in_closed_subset() and is_in_youngest() may
193 // be expensive to compute in general, so, to prevent
194 // their inadvertent use in product jvm's, we restrict their use to
195 // assertion checking or verification only.
196 bool is_in(const void* p) const;
198 // override
199 bool is_in_closed_subset(const void* p) const {
200 if (UseConcMarkSweepGC) {
201 return is_in_reserved(p);
202 } else {
203 return is_in(p);
204 }
205 }
207 // Returns true if the reference is to an object in the reserved space
208 // for the young generation.
209 // Assumes the the young gen address range is less than that of the old gen.
210 bool is_in_young(oop p);
212 #ifdef ASSERT
213 virtual bool is_in_partial_collection(const void* p);
214 #endif
216 virtual bool is_scavengable(const void* addr) {
217 return is_in_young((oop)addr);
218 }
220 // Iteration functions.
221 void oop_iterate(ExtendedOopClosure* cl);
222 void oop_iterate(MemRegion mr, ExtendedOopClosure* cl);
223 void object_iterate(ObjectClosure* cl);
224 void safe_object_iterate(ObjectClosure* cl);
225 Space* space_containing(const void* addr) const;
227 // A CollectedHeap is divided into a dense sequence of "blocks"; that is,
228 // each address in the (reserved) heap is a member of exactly
229 // one block. The defining characteristic of a block is that it is
230 // possible to find its size, and thus to progress forward to the next
231 // block. (Blocks may be of different sizes.) Thus, blocks may
232 // represent Java objects, or they might be free blocks in a
233 // free-list-based heap (or subheap), as long as the two kinds are
234 // distinguishable and the size of each is determinable.
236 // Returns the address of the start of the "block" that contains the
237 // address "addr". We say "blocks" instead of "object" since some heaps
238 // may not pack objects densely; a chunk may either be an object or a
239 // non-object.
240 virtual HeapWord* block_start(const void* addr) const;
242 // Requires "addr" to be the start of a chunk, and returns its size.
243 // "addr + size" is required to be the start of a new chunk, or the end
244 // of the active area of the heap. Assumes (and verifies in non-product
245 // builds) that addr is in the allocated part of the heap and is
246 // the start of a chunk.
247 virtual size_t block_size(const HeapWord* addr) const;
249 // Requires "addr" to be the start of a block, and returns "TRUE" iff
250 // the block is an object. Assumes (and verifies in non-product
251 // builds) that addr is in the allocated part of the heap and is
252 // the start of a chunk.
253 virtual bool block_is_obj(const HeapWord* addr) const;
255 // Section on TLAB's.
256 virtual bool supports_tlab_allocation() const;
257 virtual size_t tlab_capacity(Thread* thr) const;
258 virtual size_t unsafe_max_tlab_alloc(Thread* thr) const;
259 virtual HeapWord* allocate_new_tlab(size_t size);
261 // Can a compiler initialize a new object without store barriers?
262 // This permission only extends from the creation of a new object
263 // via a TLAB up to the first subsequent safepoint.
264 virtual bool can_elide_tlab_store_barriers() const {
265 return true;
266 }
268 virtual bool card_mark_must_follow_store() const {
269 return UseConcMarkSweepGC;
270 }
272 // We don't need barriers for stores to objects in the
273 // young gen and, a fortiori, for initializing stores to
274 // objects therein. This applies to {DefNew,ParNew}+{Tenured,CMS}
275 // only and may need to be re-examined in case other
276 // kinds of collectors are implemented in the future.
277 virtual bool can_elide_initializing_store_barrier(oop new_obj) {
278 // We wanted to assert that:-
279 // assert(UseParNewGC || UseSerialGC || UseConcMarkSweepGC,
280 // "Check can_elide_initializing_store_barrier() for this collector");
281 // but unfortunately the flag UseSerialGC need not necessarily always
282 // be set when DefNew+Tenured are being used.
283 return is_in_young(new_obj);
284 }
286 // The "requestor" generation is performing some garbage collection
287 // action for which it would be useful to have scratch space. The
288 // requestor promises to allocate no more than "max_alloc_words" in any
289 // older generation (via promotion say.) Any blocks of space that can
290 // be provided are returned as a list of ScratchBlocks, sorted by
291 // decreasing size.
292 ScratchBlock* gather_scratch(Generation* requestor, size_t max_alloc_words);
293 // Allow each generation to reset any scratch space that it has
294 // contributed as it needs.
295 void release_scratch();
297 // Ensure parsability: override
298 virtual void ensure_parsability(bool retire_tlabs);
300 // Time in ms since the longest time a collector ran in
301 // in any generation.
302 virtual jlong millis_since_last_gc();
304 // Total number of full collections completed.
305 unsigned int total_full_collections_completed() {
306 assert(_full_collections_completed <= _total_full_collections,
307 "Can't complete more collections than were started");
308 return _full_collections_completed;
309 }
311 // Update above counter, as appropriate, at the end of a stop-world GC cycle
312 unsigned int update_full_collections_completed();
313 // Update above counter, as appropriate, at the end of a concurrent GC cycle
314 unsigned int update_full_collections_completed(unsigned int count);
316 // Update "time of last gc" for all constituent generations
317 // to "now".
318 void update_time_of_last_gc(jlong now) {
319 for (int i = 0; i < _n_gens; i++) {
320 _gens[i]->update_time_of_last_gc(now);
321 }
322 }
324 // Update the gc statistics for each generation.
325 // "level" is the level of the lastest collection
326 void update_gc_stats(int current_level, bool full) {
327 for (int i = 0; i < _n_gens; i++) {
328 _gens[i]->update_gc_stats(current_level, full);
329 }
330 }
332 // Override.
333 bool no_gc_in_progress() { return !is_gc_active(); }
335 // Override.
336 void prepare_for_verify();
338 // Override.
339 void verify(bool silent, VerifyOption option);
341 // Override.
342 virtual void print_on(outputStream* st) const;
343 virtual void print_gc_threads_on(outputStream* st) const;
344 virtual void gc_threads_do(ThreadClosure* tc) const;
345 virtual void print_tracing_info() const;
346 virtual void print_on_error(outputStream* st) const;
348 // PrintGC, PrintGCDetails support
349 void print_heap_change(size_t prev_used) const;
351 // The functions below are helper functions that a subclass of
352 // "CollectedHeap" can use in the implementation of its virtual
353 // functions.
355 class GenClosure : public StackObj {
356 public:
357 virtual void do_generation(Generation* gen) = 0;
358 };
360 // Apply "cl.do_generation" to all generations in the heap
361 // If "old_to_young" determines the order.
362 void generation_iterate(GenClosure* cl, bool old_to_young);
364 void space_iterate(SpaceClosure* cl);
366 // Return "true" if all generations have reached the
367 // maximal committed limit that they can reach, without a garbage
368 // collection.
369 virtual bool is_maximal_no_gc() const;
371 // Return the generation before "gen", or else NULL.
372 Generation* prev_gen(Generation* gen) const {
373 int l = gen->level();
374 if (l == 0) return NULL;
375 else return _gens[l-1];
376 }
378 // Return the generation after "gen", or else NULL.
379 Generation* next_gen(Generation* gen) const {
380 int l = gen->level() + 1;
381 if (l == _n_gens) return NULL;
382 else return _gens[l];
383 }
385 Generation* get_gen(int i) const {
386 if (i >= 0 && i < _n_gens)
387 return _gens[i];
388 else
389 return NULL;
390 }
392 int n_gens() const {
393 assert(_n_gens == gen_policy()->number_of_generations(), "Sanity");
394 return _n_gens;
395 }
397 // Convenience function to be used in situations where the heap type can be
398 // asserted to be this type.
399 static GenCollectedHeap* heap();
401 void set_par_threads(uint t);
403 // Invoke the "do_oop" method of one of the closures "not_older_gens"
404 // or "older_gens" on root locations for the generation at
405 // "level". (The "older_gens" closure is used for scanning references
406 // from older generations; "not_older_gens" is used everywhere else.)
407 // If "younger_gens_as_roots" is false, younger generations are
408 // not scanned as roots; in this case, the caller must be arranging to
409 // scan the younger generations itself. (For example, a generation might
410 // explicitly mark reachable objects in younger generations, to avoid
411 // excess storage retention.)
412 // The "so" argument determines which of the roots
413 // the closure is applied to:
414 // "SO_None" does none;
415 // "SO_AllClasses" applies the closure to all entries in the SystemDictionary;
416 // "SO_SystemClasses" to all the "system" classes and loaders;
417 // "SO_Strings" applies the closure to all entries in the StringTable.
418 void gen_process_strong_roots(int level,
419 bool younger_gens_as_roots,
420 // The remaining arguments are in an order
421 // consistent with SharedHeap::process_strong_roots:
422 bool activate_scope,
423 bool is_scavenging,
424 SharedHeap::ScanningOption so,
425 OopsInGenClosure* not_older_gens,
426 bool do_code_roots,
427 OopsInGenClosure* older_gens,
428 KlassClosure* klass_closure);
430 // Apply "blk" to all the weak roots of the system. These include
431 // JNI weak roots, the code cache, system dictionary, symbol table,
432 // string table, and referents of reachable weak refs.
433 void gen_process_weak_roots(OopClosure* root_closure,
434 CodeBlobClosure* code_roots);
436 // Set the saved marks of generations, if that makes sense.
437 // In particular, if any generation might iterate over the oops
438 // in other generations, it should call this method.
439 void save_marks();
441 // Apply "cur->do_oop" or "older->do_oop" to all the oops in objects
442 // allocated since the last call to save_marks in generations at or above
443 // "level". The "cur" closure is
444 // applied to references in the generation at "level", and the "older"
445 // closure to older generations.
446 #define GCH_SINCE_SAVE_MARKS_ITERATE_DECL(OopClosureType, nv_suffix) \
447 void oop_since_save_marks_iterate(int level, \
448 OopClosureType* cur, \
449 OopClosureType* older);
451 ALL_SINCE_SAVE_MARKS_CLOSURES(GCH_SINCE_SAVE_MARKS_ITERATE_DECL)
453 #undef GCH_SINCE_SAVE_MARKS_ITERATE_DECL
455 // Returns "true" iff no allocations have occurred in any generation at
456 // "level" or above since the last
457 // call to "save_marks".
458 bool no_allocs_since_save_marks(int level);
460 // Returns true if an incremental collection is likely to fail.
461 // We optionally consult the young gen, if asked to do so;
462 // otherwise we base our answer on whether the previous incremental
463 // collection attempt failed with no corrective action as of yet.
464 bool incremental_collection_will_fail(bool consult_young) {
465 // Assumes a 2-generation system; the first disjunct remembers if an
466 // incremental collection failed, even when we thought (second disjunct)
467 // that it would not.
468 assert(heap()->collector_policy()->is_two_generation_policy(),
469 "the following definition may not be suitable for an n(>2)-generation system");
470 return incremental_collection_failed() ||
471 (consult_young && !get_gen(0)->collection_attempt_is_safe());
472 }
474 // If a generation bails out of an incremental collection,
475 // it sets this flag.
476 bool incremental_collection_failed() const {
477 return _incremental_collection_failed;
478 }
479 void set_incremental_collection_failed() {
480 _incremental_collection_failed = true;
481 }
482 void clear_incremental_collection_failed() {
483 _incremental_collection_failed = false;
484 }
486 // Promotion of obj into gen failed. Try to promote obj to higher
487 // gens in ascending order; return the new location of obj if successful.
488 // Otherwise, try expand-and-allocate for obj in each generation starting at
489 // gen; return the new location of obj if successful. Otherwise, return NULL.
490 oop handle_failed_promotion(Generation* gen,
491 oop obj,
492 size_t obj_size);
494 private:
495 // Accessor for memory state verification support
496 NOT_PRODUCT(
497 static size_t skip_header_HeapWords() { return _skip_header_HeapWords; }
498 )
500 // Override
501 void check_for_non_bad_heap_word_value(HeapWord* addr,
502 size_t size) PRODUCT_RETURN;
504 // For use by mark-sweep. As implemented, mark-sweep-compact is global
505 // in an essential way: compaction is performed across generations, by
506 // iterating over spaces.
507 void prepare_for_compaction();
509 // Perform a full collection of the first max_level+1 generations.
510 // This is the low level interface used by the public versions of
511 // collect() and collect_locked(). Caller holds the Heap_lock on entry.
512 void collect_locked(GCCause::Cause cause, int max_level);
514 // Returns success or failure.
515 bool create_cms_collector();
517 // In support of ExplicitGCInvokesConcurrent functionality
518 bool should_do_concurrent_full_gc(GCCause::Cause cause);
519 void collect_mostly_concurrent(GCCause::Cause cause);
521 // Save the tops of the spaces in all generations
522 void record_gen_tops_before_GC() PRODUCT_RETURN;
524 protected:
525 virtual void gc_prologue(bool full);
526 virtual void gc_epilogue(bool full);
527 };
529 #endif // SHARE_VM_MEMORY_GENCOLLECTEDHEAP_HPP