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