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3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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24
25 #ifndef SHARE_GC_SHARED_GENCOLLECTEDHEAP_HPP
26 #define SHARE_GC_SHARED_GENCOLLECTEDHEAP_HPP
27
28 #include "gc/shared/collectedHeap.hpp"
29 #include "gc/shared/collectorPolicy.hpp"
30 #include "gc/shared/generation.hpp"
31 #include "gc/shared/oopStorageParState.hpp"
32 #include "gc/shared/softRefGenPolicy.hpp"
33
34 class AdaptiveSizePolicy;
35 class GCPolicyCounters;
36 class GenerationSpec;
37 class StrongRootsScope;
38 class SubTasksDone;
39 class WorkGang;
40
41 // A "GenCollectedHeap" is a CollectedHeap that uses generational
42 // collection. It has two generations, young and old.
43 class GenCollectedHeap : public CollectedHeap {
44 friend class GenCollectorPolicy;
45 friend class Generation;
46 friend class DefNewGeneration;
47 friend class TenuredGeneration;
48 friend class ConcurrentMarkSweepGeneration;
49 friend class CMSCollector;
50 friend class GenMarkSweep;
51 friend class VM_GenCollectForAllocation;
52 friend class VM_GenCollectFull;
53 friend class VM_GenCollectFullConcurrent;
54 friend class VM_GC_HeapInspection;
55 friend class VM_HeapDumper;
56 friend class HeapInspection;
57 friend class GCCauseSetter;
58 friend class VMStructs;
59 public:
60 friend class VM_PopulateDumpSharedSpace;
61
62 enum GenerationType {
63 YoungGen,
64 OldGen
65 };
66
67 protected:
68 Generation* _young_gen;
69 Generation* _old_gen;
70
71 private:
72 GenerationSpec* _young_gen_spec;
73 GenerationSpec* _old_gen_spec;
74
75 // The singleton CardTable Remembered Set.
76 CardTableRS* _rem_set;
77
78 // The generational collector policy.
79 GenCollectorPolicy* _gen_policy;
80
81 SoftRefGenPolicy _soft_ref_gen_policy;
82
83 // The sizing of the heap is controlled by a sizing policy.
84 AdaptiveSizePolicy* _size_policy;
85
86 GCPolicyCounters* _gc_policy_counters;
87
88 // Indicates that the most recent previous incremental collection failed.
89 // The flag is cleared when an action is taken that might clear the
90 // condition that caused that incremental collection to fail.
91 bool _incremental_collection_failed;
92
93 // In support of ExplicitGCInvokesConcurrent functionality
94 unsigned int _full_collections_completed;
95
96 // Collects the given generation.
97 void collect_generation(Generation* gen, bool full, size_t size, bool is_tlab,
98 bool run_verification, bool clear_soft_refs,
99 bool restore_marks_for_biased_locking);
100
101 // Reserve aligned space for the heap as needed by the contained generations.
102 char* allocate(size_t alignment, ReservedSpace* heap_rs);
103
104 // Initialize ("weak") refs processing support
105 void ref_processing_init();
106
107 protected:
108
109 // The set of potentially parallel tasks in root scanning.
110 enum GCH_strong_roots_tasks {
111 GCH_PS_Universe_oops_do,
112 GCH_PS_JNIHandles_oops_do,
113 GCH_PS_ObjectSynchronizer_oops_do,
114 GCH_PS_FlatProfiler_oops_do,
115 GCH_PS_Management_oops_do,
116 GCH_PS_SystemDictionary_oops_do,
117 GCH_PS_ClassLoaderDataGraph_oops_do,
118 GCH_PS_jvmti_oops_do,
119 GCH_PS_CodeCache_oops_do,
120 GCH_PS_aot_oops_do,
121 GCH_PS_younger_gens,
122 // Leave this one last.
123 GCH_PS_NumElements
124 };
125
126 // Data structure for claiming the (potentially) parallel tasks in
127 // (gen-specific) roots processing.
128 SubTasksDone* _process_strong_tasks;
129
130 GCMemoryManager* _young_manager;
131 GCMemoryManager* _old_manager;
132
133 // Helper functions for allocation
134 HeapWord* attempt_allocation(size_t size,
135 bool is_tlab,
136 bool first_only);
137
138 // Helper function for two callbacks below.
139 // Considers collection of the first max_level+1 generations.
140 void do_collection(bool full,
141 bool clear_all_soft_refs,
142 size_t size,
143 bool is_tlab,
144 GenerationType max_generation);
145
146 // Callback from VM_GenCollectForAllocation operation.
147 // This function does everything necessary/possible to satisfy an
148 // allocation request that failed in the youngest generation that should
149 // have handled it (including collection, expansion, etc.)
150 HeapWord* satisfy_failed_allocation(size_t size, bool is_tlab);
151
152 // Callback from VM_GenCollectFull operation.
153 // Perform a full collection of the first max_level+1 generations.
154 virtual void do_full_collection(bool clear_all_soft_refs);
155 void do_full_collection(bool clear_all_soft_refs, GenerationType max_generation);
156
157 // Does the "cause" of GC indicate that
158 // we absolutely __must__ clear soft refs?
159 bool must_clear_all_soft_refs();
160
161 GenCollectedHeap(GenCollectorPolicy *policy,
162 Generation::Name young,
163 Generation::Name old,
164 const char* policy_counters_name);
165
166 public:
167
168 // Returns JNI_OK on success
169 virtual jint initialize();
170 virtual CardTableRS* create_rem_set(const MemRegion& reserved_region);
171
172 void initialize_size_policy(size_t init_eden_size,
173 size_t init_promo_size,
174 size_t init_survivor_size);
175
176 // Does operations required after initialization has been done.
177 void post_initialize();
178
179 Generation* young_gen() const { return _young_gen; }
180 Generation* old_gen() const { return _old_gen; }
181
182 bool is_young_gen(const Generation* gen) const { return gen == _young_gen; }
183 bool is_old_gen(const Generation* gen) const { return gen == _old_gen; }
184
185 GenerationSpec* young_gen_spec() const;
186 GenerationSpec* old_gen_spec() const;
187
188 // The generational collector policy.
189 GenCollectorPolicy* gen_policy() const { return _gen_policy; }
190
191 virtual CollectorPolicy* collector_policy() const { return gen_policy(); }
192
193 virtual SoftRefPolicy* soft_ref_policy() { return &_soft_ref_gen_policy; }
194
195 // Adaptive size policy
196 virtual AdaptiveSizePolicy* size_policy() {
197 return _size_policy;
198 }
199
200 // Performance Counter support
201 GCPolicyCounters* counters() { return _gc_policy_counters; }
202
203 // Return the (conservative) maximum heap alignment
204 static size_t conservative_max_heap_alignment() {
205 return Generation::GenGrain;
206 }
207
208 size_t capacity() const;
209 size_t used() const;
210
211 // Save the "used_region" for both generations.
212 void save_used_regions();
213
214 size_t max_capacity() const;
215
216 HeapWord* mem_allocate(size_t size, bool* gc_overhead_limit_was_exceeded);
217
218 // We may support a shared contiguous allocation area, if the youngest
219 // generation does.
220 bool supports_inline_contig_alloc() const;
221 HeapWord* volatile* top_addr() const;
222 HeapWord** end_addr() const;
223
224 // Perform a full collection of the heap; intended for use in implementing
225 // "System.gc". This implies as full a collection as the CollectedHeap
226 // supports. Caller does not hold the Heap_lock on entry.
227 virtual void collect(GCCause::Cause cause);
228
229 // The same as above but assume that the caller holds the Heap_lock.
230 void collect_locked(GCCause::Cause cause);
231
232 // Perform a full collection of generations up to and including max_generation.
233 // Mostly used for testing purposes. Caller does not hold the Heap_lock on entry.
234 void collect(GCCause::Cause cause, GenerationType max_generation);
235
236 // Returns "TRUE" iff "p" points into the committed areas of the heap.
237 // The methods is_in(), is_in_closed_subset() and is_in_youngest() may
238 // be expensive to compute in general, so, to prevent
239 // their inadvertent use in product jvm's, we restrict their use to
240 // assertion checking or verification only.
241 bool is_in(const void* p) const;
242
243 // Returns true if the reference is to an object in the reserved space
244 // for the young generation.
245 // Assumes the the young gen address range is less than that of the old gen.
246 bool is_in_young(oop p);
247
248 #ifdef ASSERT
249 bool is_in_partial_collection(const void* p);
250 #endif
251
252 virtual bool is_scavengable(oop obj) {
253 return is_in_young(obj);
254 }
255
256 // Optimized nmethod scanning support routines
257 virtual void register_nmethod(nmethod* nm);
258 virtual void verify_nmethod(nmethod* nmethod);
259
260 // Iteration functions.
261 void oop_iterate(OopIterateClosure* cl);
262 void object_iterate(ObjectClosure* cl);
263 void safe_object_iterate(ObjectClosure* cl);
264 Space* space_containing(const void* addr) const;
265
266 // A CollectedHeap is divided into a dense sequence of "blocks"; that is,
267 // each address in the (reserved) heap is a member of exactly
268 // one block. The defining characteristic of a block is that it is
269 // possible to find its size, and thus to progress forward to the next
270 // block. (Blocks may be of different sizes.) Thus, blocks may
271 // represent Java objects, or they might be free blocks in a
272 // free-list-based heap (or subheap), as long as the two kinds are
273 // distinguishable and the size of each is determinable.
274
275 // Returns the address of the start of the "block" that contains the
276 // address "addr". We say "blocks" instead of "object" since some heaps
277 // may not pack objects densely; a chunk may either be an object or a
278 // non-object.
279 virtual HeapWord* block_start(const void* addr) const;
280
281 // Requires "addr" to be the start of a chunk, and returns its size.
282 // "addr + size" is required to be the start of a new chunk, or the end
283 // of the active area of the heap. Assumes (and verifies in non-product
284 // builds) that addr is in the allocated part of the heap and is
285 // the start of a chunk.
286 virtual size_t block_size(const HeapWord* addr) const;
287
288 // Requires "addr" to be the start of a block, and returns "TRUE" iff
289 // the block is an object. Assumes (and verifies in non-product
290 // builds) that addr is in the allocated part of the heap and is
291 // the start of a chunk.
292 virtual bool block_is_obj(const HeapWord* addr) const;
293
294 // Section on TLAB's.
295 virtual bool supports_tlab_allocation() const;
296 virtual size_t tlab_capacity(Thread* thr) const;
297 virtual size_t tlab_used(Thread* thr) const;
298 virtual size_t unsafe_max_tlab_alloc(Thread* thr) const;
299 virtual HeapWord* allocate_new_tlab(size_t min_size,
300 size_t requested_size,
301 size_t* actual_size);
302
303 // The "requestor" generation is performing some garbage collection
304 // action for which it would be useful to have scratch space. The
305 // requestor promises to allocate no more than "max_alloc_words" in any
306 // older generation (via promotion say.) Any blocks of space that can
307 // be provided are returned as a list of ScratchBlocks, sorted by
308 // decreasing size.
309 ScratchBlock* gather_scratch(Generation* requestor, size_t max_alloc_words);
310 // Allow each generation to reset any scratch space that it has
311 // contributed as it needs.
312 void release_scratch();
313
314 // Ensure parsability: override
315 virtual void ensure_parsability(bool retire_tlabs);
316
317 // Time in ms since the longest time a collector ran in
318 // in any generation.
319 virtual jlong millis_since_last_gc();
320
321 // Total number of full collections completed.
322 unsigned int total_full_collections_completed() {
323 assert(_full_collections_completed <= _total_full_collections,
324 "Can't complete more collections than were started");
325 return _full_collections_completed;
326 }
327
328 // Update above counter, as appropriate, at the end of a stop-world GC cycle
329 unsigned int update_full_collections_completed();
330 // Update above counter, as appropriate, at the end of a concurrent GC cycle
331 unsigned int update_full_collections_completed(unsigned int count);
332
333 // Update "time of last gc" for all generations to "now".
334 void update_time_of_last_gc(jlong now) {
335 _young_gen->update_time_of_last_gc(now);
336 _old_gen->update_time_of_last_gc(now);
337 }
338
339 // Update the gc statistics for each generation.
340 void update_gc_stats(Generation* current_generation, bool full) {
341 _old_gen->update_gc_stats(current_generation, full);
342 }
343
344 bool no_gc_in_progress() { return !is_gc_active(); }
345
346 // Override.
347 void prepare_for_verify();
348
349 // Override.
350 void verify(VerifyOption option);
351
352 // Override.
353 virtual void print_on(outputStream* st) const;
354 virtual void print_gc_threads_on(outputStream* st) const;
355 virtual void gc_threads_do(ThreadClosure* tc) const;
356 virtual void print_tracing_info() const;
357
358 void print_heap_change(size_t young_prev_used, size_t old_prev_used) const;
359
360 // The functions below are helper functions that a subclass of
361 // "CollectedHeap" can use in the implementation of its virtual
362 // functions.
363
364 class GenClosure : public StackObj {
365 public:
366 virtual void do_generation(Generation* gen) = 0;
367 };
368
369 // Apply "cl.do_generation" to all generations in the heap
370 // If "old_to_young" determines the order.
371 void generation_iterate(GenClosure* cl, bool old_to_young);
372
373 // Return "true" if all generations have reached the
374 // maximal committed limit that they can reach, without a garbage
375 // collection.
376 virtual bool is_maximal_no_gc() const;
377
378 // This function returns the CardTableRS object that allows us to scan
379 // generations in a fully generational heap.
380 CardTableRS* rem_set() { return _rem_set; }
381
382 // Convenience function to be used in situations where the heap type can be
383 // asserted to be this type.
384 static GenCollectedHeap* heap();
385
386 // The ScanningOption determines which of the roots
387 // the closure is applied to:
388 // "SO_None" does none;
389 enum ScanningOption {
390 SO_None = 0x0,
391 SO_AllCodeCache = 0x8,
392 SO_ScavengeCodeCache = 0x10
393 };
394
395 protected:
396 void process_roots(StrongRootsScope* scope,
397 ScanningOption so,
398 OopClosure* strong_roots,
399 CLDClosure* strong_cld_closure,
400 CLDClosure* weak_cld_closure,
401 CodeBlobToOopClosure* code_roots);
402
403 void process_string_table_roots(StrongRootsScope* scope,
404 OopClosure* root_closure,
405 OopStorage::ParState<false, false>* par_state_string);
406
407 // Accessor for memory state verification support
408 NOT_PRODUCT(
409 virtual size_t skip_header_HeapWords() { return 0; }
410 )
411
412 virtual void gc_prologue(bool full);
413 virtual void gc_epilogue(bool full);
414
415 public:
416 void young_process_roots(StrongRootsScope* scope,
417 OopsInGenClosure* root_closure,
418 OopsInGenClosure* old_gen_closure,
419 CLDClosure* cld_closure,
420 OopStorage::ParState<false, false>* par_state_string = NULL);
421
422 void full_process_roots(StrongRootsScope* scope,
423 bool is_adjust_phase,
424 ScanningOption so,
425 bool only_strong_roots,
426 OopsInGenClosure* root_closure,
427 CLDClosure* cld_closure,
428 OopStorage::ParState<false, false>* par_state_string = NULL);
429
430 // Apply "root_closure" to all the weak roots of the system.
431 // These include JNI weak roots, string table,
432 // and referents of reachable weak refs.
433 void gen_process_weak_roots(OopClosure* root_closure);
434
435 // Set the saved marks of generations, if that makes sense.
436 // In particular, if any generation might iterate over the oops
437 // in other generations, it should call this method.
438 void save_marks();
439
440 // Returns "true" iff no allocations have occurred since the last
441 // call to "save_marks".
442 bool no_allocs_since_save_marks();
443
444 // Returns true if an incremental collection is likely to fail.
445 // We optionally consult the young gen, if asked to do so;
446 // otherwise we base our answer on whether the previous incremental
447 // collection attempt failed with no corrective action as of yet.
448 bool incremental_collection_will_fail(bool consult_young) {
449 // The first disjunct remembers if an incremental collection failed, even
450 // when we thought (second disjunct) that it would not.
451 return incremental_collection_failed() ||
452 (consult_young && !_young_gen->collection_attempt_is_safe());
453 }
454
455 // If a generation bails out of an incremental collection,
456 // it sets this flag.
457 bool incremental_collection_failed() const {
458 return _incremental_collection_failed;
459 }
460 void set_incremental_collection_failed() {
461 _incremental_collection_failed = true;
462 }
463 void clear_incremental_collection_failed() {
464 _incremental_collection_failed = false;
465 }
466
467 // Promotion of obj into gen failed. Try to promote obj to higher
468 // gens in ascending order; return the new location of obj if successful.
469 // Otherwise, try expand-and-allocate for obj in both the young and old
470 // generation; return the new location of obj if successful. Otherwise, return NULL.
471 oop handle_failed_promotion(Generation* old_gen,
472 oop obj,
473 size_t obj_size);
474
475
476 private:
477 // Return true if an allocation should be attempted in the older generation
478 // if it fails in the younger generation. Return false, otherwise.
479 bool should_try_older_generation_allocation(size_t word_size) const;
480
481 // Try to allocate space by expanding the heap.
482 HeapWord* expand_heap_and_allocate(size_t size, bool is_tlab);
483
484 HeapWord* mem_allocate_work(size_t size,
485 bool is_tlab,
486 bool* gc_overhead_limit_was_exceeded);
487
488 // Override
489 void check_for_non_bad_heap_word_value(HeapWord* addr,
490 size_t size) PRODUCT_RETURN;
491
492 #if INCLUDE_SERIALGC
493 // For use by mark-sweep. As implemented, mark-sweep-compact is global
494 // in an essential way: compaction is performed across generations, by
495 // iterating over spaces.
496 void prepare_for_compaction();
497 #endif
498
499 // Perform a full collection of the generations up to and including max_generation.
500 // This is the low level interface used by the public versions of
501 // collect() and collect_locked(). Caller holds the Heap_lock on entry.
502 void collect_locked(GCCause::Cause cause, GenerationType max_generation);
503
504 // Save the tops of the spaces in all generations
505 void record_gen_tops_before_GC() PRODUCT_RETURN;
506 };
507
508 #endif // SHARE_GC_SHARED_GENCOLLECTEDHEAP_HPP