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