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comparison src/share/vm/memory/genCollectedHeap.hpp @ 0:a61af66fc99e jdk7-b24
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author | duke |
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date | Sat, 01 Dec 2007 00:00:00 +0000 |
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children | ba764ed4b6f2 c0492d52d55b |
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1 /* | |
2 * Copyright 2000-2007 Sun Microsystems, Inc. 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, | |
20 * CA 95054 USA or visit www.sun.com if you need additional information or | |
21 * have any questions. | |
22 * | |
23 */ | |
24 | |
25 class SubTasksDone; | |
26 | |
27 // A "GenCollectedHeap" is a SharedHeap that uses generational | |
28 // collection. It is represented with a sequence of Generation's. | |
29 class GenCollectedHeap : public SharedHeap { | |
30 friend class GenCollectorPolicy; | |
31 friend class Generation; | |
32 friend class DefNewGeneration; | |
33 friend class TenuredGeneration; | |
34 friend class ConcurrentMarkSweepGeneration; | |
35 friend class CMSCollector; | |
36 friend class GenMarkSweep; | |
37 friend class VM_GenCollectForAllocation; | |
38 friend class VM_GenCollectFull; | |
39 friend class VM_GenCollectFullConcurrent; | |
40 friend class VM_GC_HeapInspection; | |
41 friend class VM_HeapDumper; | |
42 friend class HeapInspection; | |
43 friend class GCCauseSetter; | |
44 friend class VMStructs; | |
45 public: | |
46 enum SomeConstants { | |
47 max_gens = 10 | |
48 }; | |
49 | |
50 friend class VM_PopulateDumpSharedSpace; | |
51 | |
52 protected: | |
53 // Fields: | |
54 static GenCollectedHeap* _gch; | |
55 | |
56 private: | |
57 int _n_gens; | |
58 Generation* _gens[max_gens]; | |
59 GenerationSpec** _gen_specs; | |
60 | |
61 // The generational collector policy. | |
62 GenCollectorPolicy* _gen_policy; | |
63 | |
64 // If a generation would bail out of an incremental collection, | |
65 // it sets this flag. If the flag is set, satisfy_failed_allocation | |
66 // will attempt allocating in all generations before doing a full GC. | |
67 bool _incremental_collection_will_fail; | |
68 bool _last_incremental_collection_failed; | |
69 | |
70 // In support of ExplicitGCInvokesConcurrent functionality | |
71 unsigned int _full_collections_completed; | |
72 | |
73 // Data structure for claiming the (potentially) parallel tasks in | |
74 // (gen-specific) strong roots processing. | |
75 SubTasksDone* _gen_process_strong_tasks; | |
76 | |
77 // In block contents verification, the number of header words to skip | |
78 NOT_PRODUCT(static size_t _skip_header_HeapWords;) | |
79 | |
80 // GC is not allowed during the dump of the shared classes. Keep track | |
81 // of this in order to provide an reasonable error message when terminating. | |
82 bool _preloading_shared_classes; | |
83 | |
84 protected: | |
85 // Directs each generation up to and including "collectedGen" to recompute | |
86 // its desired size. | |
87 void compute_new_generation_sizes(int collectedGen); | |
88 | |
89 // Helper functions for allocation | |
90 HeapWord* attempt_allocation(size_t size, | |
91 bool is_tlab, | |
92 bool first_only); | |
93 | |
94 // Helper function for two callbacks below. | |
95 // Considers collection of the first max_level+1 generations. | |
96 void do_collection(bool full, | |
97 bool clear_all_soft_refs, | |
98 size_t size, | |
99 bool is_tlab, | |
100 int max_level); | |
101 | |
102 // Callback from VM_GenCollectForAllocation operation. | |
103 // This function does everything necessary/possible to satisfy an | |
104 // allocation request that failed in the youngest generation that should | |
105 // have handled it (including collection, expansion, etc.) | |
106 HeapWord* satisfy_failed_allocation(size_t size, bool is_tlab); | |
107 | |
108 // Callback from VM_GenCollectFull operation. | |
109 // Perform a full collection of the first max_level+1 generations. | |
110 void do_full_collection(bool clear_all_soft_refs, int max_level); | |
111 | |
112 // Does the "cause" of GC indicate that | |
113 // we absolutely __must__ clear soft refs? | |
114 bool must_clear_all_soft_refs(); | |
115 | |
116 public: | |
117 GenCollectedHeap(GenCollectorPolicy *policy); | |
118 | |
119 GCStats* gc_stats(int level) const; | |
120 | |
121 // Returns JNI_OK on success | |
122 virtual jint initialize(); | |
123 char* allocate(size_t alignment, PermanentGenerationSpec* perm_gen_spec, | |
124 size_t* _total_reserved, int* _n_covered_regions, | |
125 ReservedSpace* heap_rs); | |
126 | |
127 // Does operations required after initialization has been done. | |
128 void post_initialize(); | |
129 | |
130 // Initialize ("weak") refs processing support | |
131 virtual void ref_processing_init(); | |
132 | |
133 virtual CollectedHeap::Name kind() const { | |
134 return CollectedHeap::GenCollectedHeap; | |
135 } | |
136 | |
137 // The generational collector policy. | |
138 GenCollectorPolicy* gen_policy() const { return _gen_policy; } | |
139 | |
140 // Adaptive size policy | |
141 virtual AdaptiveSizePolicy* size_policy() { | |
142 return gen_policy()->size_policy(); | |
143 } | |
144 | |
145 size_t capacity() const; | |
146 size_t used() const; | |
147 | |
148 // Save the "used_region" for generations level and lower, | |
149 // and, if perm is true, for perm gen. | |
150 void save_used_regions(int level, bool perm); | |
151 | |
152 size_t max_capacity() const; | |
153 | |
154 HeapWord* mem_allocate(size_t size, | |
155 bool is_large_noref, | |
156 bool is_tlab, | |
157 bool* gc_overhead_limit_was_exceeded); | |
158 | |
159 // We may support a shared contiguous allocation area, if the youngest | |
160 // generation does. | |
161 bool supports_inline_contig_alloc() const; | |
162 HeapWord** top_addr() const; | |
163 HeapWord** end_addr() const; | |
164 | |
165 // Return an estimate of the maximum allocation that could be performed | |
166 // without triggering any collection activity. In a generational | |
167 // collector, for example, this is probably the largest allocation that | |
168 // could be supported in the youngest generation. It is "unsafe" because | |
169 // no locks are taken; the result should be treated as an approximation, | |
170 // not a guarantee. | |
171 size_t unsafe_max_alloc(); | |
172 | |
173 // Does this heap support heap inspection? (+PrintClassHistogram) | |
174 virtual bool supports_heap_inspection() const { return true; } | |
175 | |
176 // Perform a full collection of the heap; intended for use in implementing | |
177 // "System.gc". This implies as full a collection as the CollectedHeap | |
178 // supports. Caller does not hold the Heap_lock on entry. | |
179 void collect(GCCause::Cause cause); | |
180 | |
181 // This interface assumes that it's being called by the | |
182 // vm thread. It collects the heap assuming that the | |
183 // heap lock is already held and that we are executing in | |
184 // the context of the vm thread. | |
185 void collect_as_vm_thread(GCCause::Cause cause); | |
186 | |
187 // The same as above but assume that the caller holds the Heap_lock. | |
188 void collect_locked(GCCause::Cause cause); | |
189 | |
190 // Perform a full collection of the first max_level+1 generations. | |
191 // Mostly used for testing purposes. Caller does not hold the Heap_lock on entry. | |
192 void collect(GCCause::Cause cause, int max_level); | |
193 | |
194 // Returns "TRUE" iff "p" points into the allocated area of the heap. | |
195 // The methods is_in(), is_in_closed_subset() and is_in_youngest() may | |
196 // be expensive to compute in general, so, to prevent | |
197 // their inadvertent use in product jvm's, we restrict their use to | |
198 // assertion checking or verification only. | |
199 bool is_in(const void* p) const; | |
200 | |
201 // override | |
202 bool is_in_closed_subset(const void* p) const { | |
203 if (UseConcMarkSweepGC) { | |
204 return is_in_reserved(p); | |
205 } else { | |
206 return is_in(p); | |
207 } | |
208 } | |
209 | |
210 // Returns "TRUE" iff "p" points into the youngest generation. | |
211 bool is_in_youngest(void* p); | |
212 | |
213 // Iteration functions. | |
214 void oop_iterate(OopClosure* cl); | |
215 void oop_iterate(MemRegion mr, OopClosure* cl); | |
216 void object_iterate(ObjectClosure* cl); | |
217 void object_iterate_since_last_GC(ObjectClosure* cl); | |
218 Space* space_containing(const void* addr) const; | |
219 | |
220 // A CollectedHeap is divided into a dense sequence of "blocks"; that is, | |
221 // each address in the (reserved) heap is a member of exactly | |
222 // one block. The defining characteristic of a block is that it is | |
223 // possible to find its size, and thus to progress forward to the next | |
224 // block. (Blocks may be of different sizes.) Thus, blocks may | |
225 // represent Java objects, or they might be free blocks in a | |
226 // free-list-based heap (or subheap), as long as the two kinds are | |
227 // distinguishable and the size of each is determinable. | |
228 | |
229 // Returns the address of the start of the "block" that contains the | |
230 // address "addr". We say "blocks" instead of "object" since some heaps | |
231 // may not pack objects densely; a chunk may either be an object or a | |
232 // non-object. | |
233 virtual HeapWord* block_start(const void* addr) const; | |
234 | |
235 // Requires "addr" to be the start of a chunk, and returns its size. | |
236 // "addr + size" is required to be the start of a new chunk, or the end | |
237 // of the active area of the heap. Assumes (and verifies in non-product | |
238 // builds) that addr is in the allocated part of the heap and is | |
239 // the start of a chunk. | |
240 virtual size_t block_size(const HeapWord* addr) const; | |
241 | |
242 // Requires "addr" to be the start of a block, and returns "TRUE" iff | |
243 // the block is an object. Assumes (and verifies in non-product | |
244 // builds) that addr is in the allocated part of the heap and is | |
245 // the start of a chunk. | |
246 virtual bool block_is_obj(const HeapWord* addr) const; | |
247 | |
248 // Section on TLAB's. | |
249 virtual bool supports_tlab_allocation() const; | |
250 virtual size_t tlab_capacity(Thread* thr) const; | |
251 virtual size_t unsafe_max_tlab_alloc(Thread* thr) const; | |
252 virtual HeapWord* allocate_new_tlab(size_t size); | |
253 | |
254 // The "requestor" generation is performing some garbage collection | |
255 // action for which it would be useful to have scratch space. The | |
256 // requestor promises to allocate no more than "max_alloc_words" in any | |
257 // older generation (via promotion say.) Any blocks of space that can | |
258 // be provided are returned as a list of ScratchBlocks, sorted by | |
259 // decreasing size. | |
260 ScratchBlock* gather_scratch(Generation* requestor, size_t max_alloc_words); | |
261 | |
262 size_t large_typearray_limit(); | |
263 | |
264 // Ensure parsability: override | |
265 virtual void ensure_parsability(bool retire_tlabs); | |
266 | |
267 // Time in ms since the longest time a collector ran in | |
268 // in any generation. | |
269 virtual jlong millis_since_last_gc(); | |
270 | |
271 // Total number of full collections completed. | |
272 unsigned int total_full_collections_completed() { | |
273 assert(_full_collections_completed <= _total_full_collections, | |
274 "Can't complete more collections than were started"); | |
275 return _full_collections_completed; | |
276 } | |
277 | |
278 // Update above counter, as appropriate, at the end of a stop-world GC cycle | |
279 unsigned int update_full_collections_completed(); | |
280 // Update above counter, as appropriate, at the end of a concurrent GC cycle | |
281 unsigned int update_full_collections_completed(unsigned int count); | |
282 | |
283 // Update "time of last gc" for all constituent generations | |
284 // to "now". | |
285 void update_time_of_last_gc(jlong now) { | |
286 for (int i = 0; i < _n_gens; i++) { | |
287 _gens[i]->update_time_of_last_gc(now); | |
288 } | |
289 perm_gen()->update_time_of_last_gc(now); | |
290 } | |
291 | |
292 // Update the gc statistics for each generation. | |
293 // "level" is the level of the lastest collection | |
294 void update_gc_stats(int current_level, bool full) { | |
295 for (int i = 0; i < _n_gens; i++) { | |
296 _gens[i]->update_gc_stats(current_level, full); | |
297 } | |
298 perm_gen()->update_gc_stats(current_level, full); | |
299 } | |
300 | |
301 // Override. | |
302 bool no_gc_in_progress() { return !is_gc_active(); } | |
303 | |
304 // Override. | |
305 void prepare_for_verify(); | |
306 | |
307 // Override. | |
308 void verify(bool allow_dirty, bool silent); | |
309 | |
310 // Override. | |
311 void print() const; | |
312 void print_on(outputStream* st) const; | |
313 virtual void print_gc_threads_on(outputStream* st) const; | |
314 virtual void gc_threads_do(ThreadClosure* tc) const; | |
315 virtual void print_tracing_info() const; | |
316 | |
317 // PrintGC, PrintGCDetails support | |
318 void print_heap_change(size_t prev_used) const; | |
319 void print_perm_heap_change(size_t perm_prev_used) const; | |
320 | |
321 // The functions below are helper functions that a subclass of | |
322 // "CollectedHeap" can use in the implementation of its virtual | |
323 // functions. | |
324 | |
325 class GenClosure : public StackObj { | |
326 public: | |
327 virtual void do_generation(Generation* gen) = 0; | |
328 }; | |
329 | |
330 // Apply "cl.do_generation" to all generations in the heap (not including | |
331 // the permanent generation). If "old_to_young" determines the order. | |
332 void generation_iterate(GenClosure* cl, bool old_to_young); | |
333 | |
334 void space_iterate(SpaceClosure* cl); | |
335 | |
336 // Return "true" if all generations (but perm) have reached the | |
337 // maximal committed limit that they can reach, without a garbage | |
338 // collection. | |
339 virtual bool is_maximal_no_gc() const; | |
340 | |
341 // Return the generation before "gen", or else NULL. | |
342 Generation* prev_gen(Generation* gen) const { | |
343 int l = gen->level(); | |
344 if (l == 0) return NULL; | |
345 else return _gens[l-1]; | |
346 } | |
347 | |
348 // Return the generation after "gen", or else NULL. | |
349 Generation* next_gen(Generation* gen) const { | |
350 int l = gen->level() + 1; | |
351 if (l == _n_gens) return NULL; | |
352 else return _gens[l]; | |
353 } | |
354 | |
355 Generation* get_gen(int i) const { | |
356 if (i >= 0 && i < _n_gens) | |
357 return _gens[i]; | |
358 else | |
359 return NULL; | |
360 } | |
361 | |
362 int n_gens() const { | |
363 assert(_n_gens == gen_policy()->number_of_generations(), "Sanity"); | |
364 return _n_gens; | |
365 } | |
366 | |
367 // Convenience function to be used in situations where the heap type can be | |
368 // asserted to be this type. | |
369 static GenCollectedHeap* heap(); | |
370 | |
371 void set_par_threads(int t); | |
372 | |
373 | |
374 // Invoke the "do_oop" method of one of the closures "not_older_gens" | |
375 // or "older_gens" on root locations for the generation at | |
376 // "level". (The "older_gens" closure is used for scanning references | |
377 // from older generations; "not_older_gens" is used everywhere else.) | |
378 // If "younger_gens_as_roots" is false, younger generations are | |
379 // not scanned as roots; in this case, the caller must be arranging to | |
380 // scan the younger generations itself. (For example, a generation might | |
381 // explicitly mark reachable objects in younger generations, to avoid | |
382 // excess storage retention.) If "collecting_perm_gen" is false, then | |
383 // roots that may only contain references to permGen objects are not | |
384 // scanned. The "so" argument determines which of the roots | |
385 // the closure is applied to: | |
386 // "SO_None" does none; | |
387 // "SO_AllClasses" applies the closure to all entries in the SystemDictionary; | |
388 // "SO_SystemClasses" to all the "system" classes and loaders; | |
389 // "SO_Symbols_and_Strings" applies the closure to all entries in | |
390 // SymbolsTable and StringTable. | |
391 void gen_process_strong_roots(int level, bool younger_gens_as_roots, | |
392 bool collecting_perm_gen, | |
393 SharedHeap::ScanningOption so, | |
394 OopsInGenClosure* older_gens, | |
395 OopsInGenClosure* not_older_gens); | |
396 | |
397 // Apply "blk" to all the weak roots of the system. These include | |
398 // JNI weak roots, the code cache, system dictionary, symbol table, | |
399 // string table, and referents of reachable weak refs. | |
400 void gen_process_weak_roots(OopClosure* root_closure, | |
401 OopClosure* non_root_closure); | |
402 | |
403 // Set the saved marks of generations, if that makes sense. | |
404 // In particular, if any generation might iterate over the oops | |
405 // in other generations, it should call this method. | |
406 void save_marks(); | |
407 | |
408 // Apply "cur->do_oop" or "older->do_oop" to all the oops in objects | |
409 // allocated since the last call to save_marks in generations at or above | |
410 // "level" (including the permanent generation.) The "cur" closure is | |
411 // applied to references in the generation at "level", and the "older" | |
412 // closure to older (and permanent) generations. | |
413 #define GCH_SINCE_SAVE_MARKS_ITERATE_DECL(OopClosureType, nv_suffix) \ | |
414 void oop_since_save_marks_iterate(int level, \ | |
415 OopClosureType* cur, \ | |
416 OopClosureType* older); | |
417 | |
418 ALL_SINCE_SAVE_MARKS_CLOSURES(GCH_SINCE_SAVE_MARKS_ITERATE_DECL) | |
419 | |
420 #undef GCH_SINCE_SAVE_MARKS_ITERATE_DECL | |
421 | |
422 // Returns "true" iff no allocations have occurred in any generation at | |
423 // "level" or above (including the permanent generation) since the last | |
424 // call to "save_marks". | |
425 bool no_allocs_since_save_marks(int level); | |
426 | |
427 // If a generation bails out of an incremental collection, | |
428 // it sets this flag. | |
429 bool incremental_collection_will_fail() { | |
430 return _incremental_collection_will_fail; | |
431 } | |
432 void set_incremental_collection_will_fail() { | |
433 _incremental_collection_will_fail = true; | |
434 } | |
435 void clear_incremental_collection_will_fail() { | |
436 _incremental_collection_will_fail = false; | |
437 } | |
438 | |
439 bool last_incremental_collection_failed() const { | |
440 return _last_incremental_collection_failed; | |
441 } | |
442 void set_last_incremental_collection_failed() { | |
443 _last_incremental_collection_failed = true; | |
444 } | |
445 void clear_last_incremental_collection_failed() { | |
446 _last_incremental_collection_failed = false; | |
447 } | |
448 | |
449 // Promotion of obj into gen failed. Try to promote obj to higher non-perm | |
450 // gens in ascending order; return the new location of obj if successful. | |
451 // Otherwise, try expand-and-allocate for obj in each generation starting at | |
452 // gen; return the new location of obj if successful. Otherwise, return NULL. | |
453 oop handle_failed_promotion(Generation* gen, | |
454 oop obj, | |
455 size_t obj_size, | |
456 oop* ref); | |
457 | |
458 private: | |
459 // Accessor for memory state verification support | |
460 NOT_PRODUCT( | |
461 static size_t skip_header_HeapWords() { return _skip_header_HeapWords; } | |
462 ) | |
463 | |
464 // Override | |
465 void check_for_non_bad_heap_word_value(HeapWord* addr, | |
466 size_t size) PRODUCT_RETURN; | |
467 | |
468 // For use by mark-sweep. As implemented, mark-sweep-compact is global | |
469 // in an essential way: compaction is performed across generations, by | |
470 // iterating over spaces. | |
471 void prepare_for_compaction(); | |
472 | |
473 // Perform a full collection of the first max_level+1 generations. | |
474 // This is the low level interface used by the public versions of | |
475 // collect() and collect_locked(). Caller holds the Heap_lock on entry. | |
476 void collect_locked(GCCause::Cause cause, int max_level); | |
477 | |
478 // Returns success or failure. | |
479 bool create_cms_collector(); | |
480 | |
481 // In support of ExplicitGCInvokesConcurrent functionality | |
482 bool should_do_concurrent_full_gc(GCCause::Cause cause); | |
483 void collect_mostly_concurrent(GCCause::Cause cause); | |
484 | |
485 protected: | |
486 virtual void gc_prologue(bool full); | |
487 virtual void gc_epilogue(bool full); | |
488 | |
489 public: | |
490 virtual void preload_and_dump(TRAPS) KERNEL_RETURN; | |
491 }; |