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