1 /*
2 * Copyright (c) 2013, 2021, Red Hat, 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #ifndef SHARE_GC_SHENANDOAH_SHENANDOAHHEAP_HPP
26 #define SHARE_GC_SHENANDOAH_SHENANDOAHHEAP_HPP
27
28 #include "gc/shared/markBitMap.hpp"
29 #include "gc/shared/softRefPolicy.hpp"
30 #include "gc/shared/collectedHeap.hpp"
31 #include "gc/shenandoah/shenandoahAsserts.hpp"
32 #include "gc/shenandoah/shenandoahAllocRequest.hpp"
33 #include "gc/shenandoah/shenandoahLock.hpp"
34 #include "gc/shenandoah/shenandoahEvacOOMHandler.hpp"
35 #include "gc/shenandoah/shenandoahPadding.hpp"
36 #include "gc/shenandoah/shenandoahSharedVariables.hpp"
37 #include "gc/shenandoah/shenandoahUnload.hpp"
38 #include "memory/metaspace.hpp"
39 #include "services/memoryManager.hpp"
40 #include "utilities/globalDefinitions.hpp"
41 #include "utilities/stack.hpp"
42
43 class ConcurrentGCTimer;
44 class ObjectIterateScanRootClosure;
45 class ShenandoahCollectorPolicy;
46 class ShenandoahControlThread;
47 class ShenandoahGCSession;
48 class ShenandoahGCStateResetter;
49 class ShenandoahHeuristics;
50 class ShenandoahMarkingContext;
51 class ShenandoahMode;
52 class ShenandoahPhaseTimings;
53 class ShenandoahHeap;
54 class ShenandoahHeapRegion;
55 class ShenandoahHeapRegionClosure;
56 class ShenandoahCollectionSet;
57 class ShenandoahFreeSet;
58 class ShenandoahConcurrentMark;
59 class ShenandoahFullGC;
60 class ShenandoahMonitoringSupport;
61 class ShenandoahPacer;
62 class ShenandoahReferenceProcessor;
63 class ShenandoahVerifier;
64 class ShenandoahWorkGang;
65 class VMStructs;
66
67 // Used for buffering per-region liveness data.
68 // Needed since ShenandoahHeapRegion uses atomics to update liveness.
69 // The ShenandoahHeap array has max-workers elements, each of which is an array of
70 // uint16_t * max_regions. The choice of uint16_t is not accidental:
71 // there is a tradeoff between static/dynamic footprint that translates
72 // into cache pressure (which is already high during marking), and
73 // too many atomic updates. uint32_t is too large, uint8_t is too small.
74 typedef uint16_t ShenandoahLiveData;
75 #define SHENANDOAH_LIVEDATA_MAX ((ShenandoahLiveData)-1)
76
77 class ShenandoahRegionIterator : public StackObj {
78 private:
79 ShenandoahHeap* _heap;
80
81 shenandoah_padding(0);
82 volatile size_t _index;
83 shenandoah_padding(1);
84
85 // No implicit copying: iterators should be passed by reference to capture the state
86 NONCOPYABLE(ShenandoahRegionIterator);
87
88 public:
89 ShenandoahRegionIterator();
90 ShenandoahRegionIterator(ShenandoahHeap* heap);
91
92 // Reset iterator to default state
93 void reset();
94
95 // Returns next region, or NULL if there are no more regions.
96 // This is multi-thread-safe.
97 inline ShenandoahHeapRegion* next();
98
99 // This is *not* MT safe. However, in the absence of multithreaded access, it
100 // can be used to determine if there is more work to do.
101 bool has_next() const;
102 };
103
104 class ShenandoahHeapRegionClosure : public StackObj {
105 public:
106 virtual void heap_region_do(ShenandoahHeapRegion* r) = 0;
107 virtual bool is_thread_safe() { return false; }
108 };
109
110 typedef ShenandoahLock ShenandoahHeapLock;
111 typedef ShenandoahLocker ShenandoahHeapLocker;
112 typedef Stack<oop, mtGC> ShenandoahScanObjectStack;
113
114 // Shenandoah GC is low-pause concurrent GC that uses Brooks forwarding pointers
115 // to encode forwarding data. See BrooksPointer for details on forwarding data encoding.
116 // See ShenandoahControlThread for GC cycle structure.
117 //
118 class ShenandoahHeap : public CollectedHeap {
119 friend class ShenandoahAsserts;
120 friend class VMStructs;
121 friend class ShenandoahGCSession;
122 friend class ShenandoahGCStateResetter;
123 friend class ShenandoahParallelObjectIterator;
124 friend class ShenandoahSafepoint;
125 // Supported GC
126 friend class ShenandoahConcurrentGC;
127 friend class ShenandoahDegenGC;
128 friend class ShenandoahFullGC;
129 friend class ShenandoahUnload;
130
131 // ---------- Locks that guard important data structures in Heap
132 //
133 private:
134 ShenandoahHeapLock _lock;
135
136 public:
137 ShenandoahHeapLock* lock() {
138 return &_lock;
139 }
140
141 // ---------- Initialization, termination, identification, printing routines
142 //
143 public:
144 static ShenandoahHeap* heap();
145
146 const char* name() const { return "Shenandoah"; }
147 ShenandoahHeap::Name kind() const { return CollectedHeap::Shenandoah; }
148
149 ShenandoahHeap(ShenandoahCollectorPolicy* policy);
150 jint initialize();
151 void post_initialize();
152 void initialize_mode();
153 void initialize_heuristics();
154
155 void initialize_serviceability();
156
157 void print_on(outputStream* st) const;
158 void print_extended_on(outputStream *st) const;
159 void print_tracing_info() const;
160 void print_heap_regions_on(outputStream* st) const;
161
162 void stop();
163
164 void prepare_for_verify();
165 void verify(VerifyOption vo);
166
167 // WhiteBox testing support.
168 bool supports_concurrent_gc_breakpoints() const {
169 return true;
170 }
171
172 // ---------- Heap counters and metrics
173 //
174 private:
175 size_t _initial_size;
176 size_t _minimum_size;
177 volatile size_t _soft_max_size;
178 shenandoah_padding(0);
179 volatile size_t _used;
180 volatile size_t _committed;
181 volatile size_t _bytes_allocated_since_gc_start;
182 shenandoah_padding(1);
183
184 public:
185 void increase_used(size_t bytes);
186 void decrease_used(size_t bytes);
187 void set_used(size_t bytes);
188
189 void increase_committed(size_t bytes);
190 void decrease_committed(size_t bytes);
191 void increase_allocated(size_t bytes);
192
193 size_t bytes_allocated_since_gc_start();
194 void reset_bytes_allocated_since_gc_start();
195
196 size_t min_capacity() const;
197 size_t max_capacity() const;
198 size_t soft_max_capacity() const;
199 size_t initial_capacity() const;
200 size_t capacity() const;
201 size_t used() const;
202 size_t committed() const;
203
204 void set_soft_max_capacity(size_t v);
205
206 // ---------- Workers handling
207 //
208 private:
209 uint _max_workers;
210 ShenandoahWorkGang* _workers;
211 ShenandoahWorkGang* _safepoint_workers;
212
213 public:
214 uint max_workers();
215 void assert_gc_workers(uint nworker) NOT_DEBUG_RETURN;
216
217 WorkGang* workers() const;
218 WorkGang* safepoint_workers();
219
220 void gc_threads_do(ThreadClosure* tcl) const;
221
222 // ---------- Heap regions handling machinery
223 //
224 private:
225 MemRegion _heap_region;
226 bool _heap_region_special;
227 size_t _num_regions;
228 ShenandoahHeapRegion** _regions;
229 ShenandoahRegionIterator _update_refs_iterator;
230
231 public:
232
233 inline HeapWord* base() const { return _heap_region.start(); }
234
235 inline size_t num_regions() const { return _num_regions; }
236 inline bool is_heap_region_special() { return _heap_region_special; }
237
238 inline ShenandoahHeapRegion* const heap_region_containing(const void* addr) const;
239 inline size_t heap_region_index_containing(const void* addr) const;
240
241 inline ShenandoahHeapRegion* const get_region(size_t region_idx) const;
242
243 void heap_region_iterate(ShenandoahHeapRegionClosure* blk) const;
244 void parallel_heap_region_iterate(ShenandoahHeapRegionClosure* blk) const;
245
246 // ---------- GC state machinery
247 //
248 // GC state describes the important parts of collector state, that may be
249 // used to make barrier selection decisions in the native and generated code.
250 // Multiple bits can be set at once.
251 //
252 // Important invariant: when GC state is zero, the heap is stable, and no barriers
253 // are required.
254 //
255 public:
256 enum GCStateBitPos {
257 // Heap has forwarded objects: needs LRB barriers.
258 HAS_FORWARDED_BITPOS = 0,
259
260 // Heap is under marking: needs SATB barriers.
261 MARKING_BITPOS = 1,
262
263 // Heap is under evacuation: needs LRB barriers. (Set together with HAS_FORWARDED)
264 EVACUATION_BITPOS = 2,
265
266 // Heap is under updating: needs no additional barriers.
267 UPDATEREFS_BITPOS = 3,
268
269 // Heap is under weak-reference/roots processing: needs weak-LRB barriers.
270 WEAK_ROOTS_BITPOS = 4,
271 };
272
273 enum GCState {
274 STABLE = 0,
275 HAS_FORWARDED = 1 << HAS_FORWARDED_BITPOS,
276 MARKING = 1 << MARKING_BITPOS,
277 EVACUATION = 1 << EVACUATION_BITPOS,
278 UPDATEREFS = 1 << UPDATEREFS_BITPOS,
279 WEAK_ROOTS = 1 << WEAK_ROOTS_BITPOS,
280 };
281
282 private:
283 ShenandoahSharedBitmap _gc_state;
284 ShenandoahSharedFlag _degenerated_gc_in_progress;
285 ShenandoahSharedFlag _full_gc_in_progress;
286 ShenandoahSharedFlag _full_gc_move_in_progress;
287 ShenandoahSharedFlag _progress_last_gc;
288 ShenandoahSharedFlag _concurrent_strong_root_in_progress;
289
290 void set_gc_state_all_threads(char state);
291 void set_gc_state_mask(uint mask, bool value);
292
293 public:
294 char gc_state() const;
295 static address gc_state_addr();
296
297 void set_concurrent_mark_in_progress(bool in_progress);
298 void set_evacuation_in_progress(bool in_progress);
299 void set_update_refs_in_progress(bool in_progress);
300 void set_degenerated_gc_in_progress(bool in_progress);
301 void set_full_gc_in_progress(bool in_progress);
302 void set_full_gc_move_in_progress(bool in_progress);
303 void set_has_forwarded_objects(bool cond);
304 void set_concurrent_strong_root_in_progress(bool cond);
305 void set_concurrent_weak_root_in_progress(bool cond);
306
307 inline bool is_stable() const;
308 inline bool is_idle() const;
309 inline bool is_concurrent_mark_in_progress() const;
310 inline bool is_update_refs_in_progress() const;
311 inline bool is_evacuation_in_progress() const;
312 inline bool is_degenerated_gc_in_progress() const;
313 inline bool is_full_gc_in_progress() const;
314 inline bool is_full_gc_move_in_progress() const;
315 inline bool has_forwarded_objects() const;
316 inline bool is_gc_in_progress_mask(uint mask) const;
317 inline bool is_stw_gc_in_progress() const;
318 inline bool is_concurrent_strong_root_in_progress() const;
319 inline bool is_concurrent_weak_root_in_progress() const;
320
321 private:
322 enum CancelState {
323 // Normal state. GC has not been cancelled and is open for cancellation.
324 // Worker threads can suspend for safepoint.
325 CANCELLABLE,
326
327 // GC has been cancelled. Worker threads can not suspend for
328 // safepoint but must finish their work as soon as possible.
329 CANCELLED,
330
331 // GC has not been cancelled and must not be cancelled. At least
332 // one worker thread checks for pending safepoint and may suspend
333 // if a safepoint is pending.
334 NOT_CANCELLED
335 };
336
337 ShenandoahSharedEnumFlag<CancelState> _cancelled_gc;
338 bool try_cancel_gc();
339
340 public:
341 static address cancelled_gc_addr();
342
343 inline bool cancelled_gc() const;
344 inline bool check_cancelled_gc_and_yield(bool sts_active = true);
345
346 inline void clear_cancelled_gc();
347
348 void cancel_gc(GCCause::Cause cause);
349
350 public:
351 // Elastic heap support
352 void entry_uncommit(double shrink_before, size_t shrink_until);
353 void op_uncommit(double shrink_before, size_t shrink_until);
354
355 private:
356 // GC support
357 // Reset bitmap, prepare regions for new GC cycle
358 void prepare_gc();
359 void prepare_regions_and_collection_set(bool concurrent);
360 // Evacuation
361 void prepare_evacuation(bool concurrent);
362 void evacuate_collection_set(bool concurrent);
363 // Concurrent root processing
364 void prepare_concurrent_roots();
365 void finish_concurrent_roots();
366 // Concurrent class unloading support
367 void do_class_unloading();
368 // Reference updating
369 void prepare_update_heap_references(bool concurrent);
370 void update_heap_references(bool concurrent);
371 // Final update region states
372 void update_heap_region_states(bool concurrent);
373 void rebuild_free_set(bool concurrent);
374
375 void rendezvous_threads();
376 void recycle_trash();
377 public:
378 void notify_gc_progress() { _progress_last_gc.set(); }
379 void notify_gc_no_progress() { _progress_last_gc.unset(); }
380
381 //
382 // Mark support
383 private:
384 ShenandoahControlThread* _control_thread;
385 ShenandoahCollectorPolicy* _shenandoah_policy;
386 ShenandoahMode* _gc_mode;
387 ShenandoahHeuristics* _heuristics;
388 ShenandoahFreeSet* _free_set;
389 ShenandoahPacer* _pacer;
390 ShenandoahVerifier* _verifier;
391
392 ShenandoahPhaseTimings* _phase_timings;
393
394 ShenandoahControlThread* control_thread() { return _control_thread; }
395
396 public:
397 ShenandoahCollectorPolicy* shenandoah_policy() const { return _shenandoah_policy; }
398 ShenandoahMode* mode() const { return _gc_mode; }
399 ShenandoahHeuristics* heuristics() const { return _heuristics; }
400 ShenandoahFreeSet* free_set() const { return _free_set; }
401 ShenandoahPacer* pacer() const { return _pacer; }
402
403 ShenandoahPhaseTimings* phase_timings() const { return _phase_timings; }
404
405 ShenandoahVerifier* verifier();
406
407 // ---------- VM subsystem bindings
408 //
409 private:
410 ShenandoahMonitoringSupport* _monitoring_support;
411 MemoryPool* _memory_pool;
412 GCMemoryManager _stw_memory_manager;
413 GCMemoryManager _cycle_memory_manager;
414 ConcurrentGCTimer* _gc_timer;
415 SoftRefPolicy _soft_ref_policy;
416
417 // For exporting to SA
418 int _log_min_obj_alignment_in_bytes;
419 public:
420 ShenandoahMonitoringSupport* monitoring_support() { return _monitoring_support; }
421 GCMemoryManager* cycle_memory_manager() { return &_cycle_memory_manager; }
422 GCMemoryManager* stw_memory_manager() { return &_stw_memory_manager; }
423 SoftRefPolicy* soft_ref_policy() { return &_soft_ref_policy; }
424
425 GrowableArray<GCMemoryManager*> memory_managers();
426 GrowableArray<MemoryPool*> memory_pools();
427 MemoryUsage memory_usage();
428 GCTracer* tracer();
429 ConcurrentGCTimer* gc_timer() const;
430
431 // ---------- Reference processing
432 //
433 private:
434 ShenandoahReferenceProcessor* const _ref_processor;
435
436 public:
437 ShenandoahReferenceProcessor* ref_processor() { return _ref_processor; }
438
439 // ---------- Class Unloading
440 //
441 private:
442 ShenandoahSharedFlag _unload_classes;
443 ShenandoahUnload _unloader;
444
445 public:
446 void set_unload_classes(bool uc);
447 bool unload_classes() const;
448
449 // Perform STW class unloading and weak root cleaning
450 void parallel_cleaning(bool full_gc);
451
452 private:
453 void stw_unload_classes(bool full_gc);
454 void stw_process_weak_roots(bool full_gc);
455 void stw_weak_refs(bool full_gc);
456
457 // Heap iteration support
458 void scan_roots_for_iteration(ShenandoahScanObjectStack* oop_stack, ObjectIterateScanRootClosure* oops);
459 bool prepare_aux_bitmap_for_iteration();
460 void reclaim_aux_bitmap_for_iteration();
461
462 // ---------- Generic interface hooks
463 // Minor things that super-interface expects us to implement to play nice with
464 // the rest of runtime. Some of the things here are not required to be implemented,
465 // and can be stubbed out.
466 //
467 public:
468 AdaptiveSizePolicy* size_policy() shenandoah_not_implemented_return(NULL);
469 bool is_maximal_no_gc() const shenandoah_not_implemented_return(false);
470
471 bool is_in(const void* p) const;
472
473 MemRegion reserved_region() const { return _reserved; }
474 bool is_in_reserved(const void* addr) const { return _reserved.contains(addr); }
475
476 void collect(GCCause::Cause cause);
477 void do_full_collection(bool clear_all_soft_refs);
478
479 // Used for parsing heap during error printing
480 HeapWord* block_start(const void* addr) const;
481 bool block_is_obj(const HeapWord* addr) const;
482 bool print_location(outputStream* st, void* addr) const;
483
484 // Used for native heap walkers: heap dumpers, mostly
485 void object_iterate(ObjectClosure* cl);
486 // Parallel heap iteration support
487 virtual ParallelObjectIterator* parallel_object_iterator(uint workers);
488
489 // Keep alive an object that was loaded with AS_NO_KEEPALIVE.
490 void keep_alive(oop obj);
491
492 // ---------- Safepoint interface hooks
493 //
494 public:
495 void safepoint_synchronize_begin();
496 void safepoint_synchronize_end();
497
498 // ---------- Code roots handling hooks
499 //
500 public:
501 void register_nmethod(nmethod* nm);
502 void unregister_nmethod(nmethod* nm);
503 void flush_nmethod(nmethod* nm);
504 void verify_nmethod(nmethod* nm) {}
505
506 // ---------- Pinning hooks
507 //
508 public:
509 // Shenandoah supports per-object (per-region) pinning
510 bool supports_object_pinning() const { return true; }
511
512 oop pin_object(JavaThread* thread, oop obj);
513 void unpin_object(JavaThread* thread, oop obj);
514
515 void sync_pinned_region_status();
516 void assert_pinned_region_status() NOT_DEBUG_RETURN;
517
518 // ---------- Concurrent Stack Processing support
519 //
520 public:
521 bool uses_stack_watermark_barrier() const { return true; }
522
523 // ---------- Allocation support
524 //
525 private:
526 HeapWord* allocate_memory_under_lock(ShenandoahAllocRequest& request, bool& in_new_region);
527 inline HeapWord* allocate_from_gclab(Thread* thread, size_t size);
528 HeapWord* allocate_from_gclab_slow(Thread* thread, size_t size);
529 HeapWord* allocate_new_gclab(size_t min_size, size_t word_size, size_t* actual_size);
530
531 public:
532 HeapWord* allocate_memory(ShenandoahAllocRequest& request);
533 HeapWord* mem_allocate(size_t size, bool* what);
534 MetaWord* satisfy_failed_metadata_allocation(ClassLoaderData* loader_data,
535 size_t size,
536 Metaspace::MetadataType mdtype);
537
538 void notify_mutator_alloc_words(size_t words, bool waste);
539
540 HeapWord* allocate_new_tlab(size_t min_size, size_t requested_size, size_t* actual_size);
541 size_t tlab_capacity(Thread *thr) const;
542 size_t unsafe_max_tlab_alloc(Thread *thread) const;
543 size_t max_tlab_size() const;
544 size_t tlab_used(Thread* ignored) const;
545
546 void ensure_parsability(bool retire_labs);
547
548 void labs_make_parsable();
549 void tlabs_retire(bool resize);
550 void gclabs_retire(bool resize);
551
552 // ---------- Marking support
553 //
554 private:
555 ShenandoahMarkingContext* _marking_context;
556 MemRegion _bitmap_region;
557 MemRegion _aux_bitmap_region;
558 MarkBitMap _verification_bit_map;
559 MarkBitMap _aux_bit_map;
560
561 size_t _bitmap_size;
562 size_t _bitmap_regions_per_slice;
563 size_t _bitmap_bytes_per_slice;
564
565 size_t _pretouch_heap_page_size;
566 size_t _pretouch_bitmap_page_size;
567
568 bool _bitmap_region_special;
569 bool _aux_bitmap_region_special;
570
571 ShenandoahLiveData** _liveness_cache;
572
573 public:
574 inline ShenandoahMarkingContext* complete_marking_context() const;
575 inline ShenandoahMarkingContext* marking_context() const;
576 inline void mark_complete_marking_context();
577 inline void mark_incomplete_marking_context();
578
579 template<class T>
580 inline void marked_object_iterate(ShenandoahHeapRegion* region, T* cl);
581
582 template<class T>
583 inline void marked_object_iterate(ShenandoahHeapRegion* region, T* cl, HeapWord* limit);
584
585 template<class T>
586 inline void marked_object_oop_iterate(ShenandoahHeapRegion* region, T* cl, HeapWord* limit);
587
588 void reset_mark_bitmap();
589
590 // SATB barriers hooks
591 inline bool requires_marking(const void* entry) const;
592
593 // Support for bitmap uncommits
594 bool commit_bitmap_slice(ShenandoahHeapRegion *r);
595 bool uncommit_bitmap_slice(ShenandoahHeapRegion *r);
596 bool is_bitmap_slice_committed(ShenandoahHeapRegion* r, bool skip_self = false);
597
598 // Liveness caching support
599 ShenandoahLiveData* get_liveness_cache(uint worker_id);
600 void flush_liveness_cache(uint worker_id);
601
602 size_t pretouch_heap_page_size() { return _pretouch_heap_page_size; }
603
604 // ---------- Evacuation support
605 //
606 private:
607 ShenandoahCollectionSet* _collection_set;
608 ShenandoahEvacOOMHandler _oom_evac_handler;
609
610 public:
611 static address in_cset_fast_test_addr();
612
613 ShenandoahCollectionSet* collection_set() const { return _collection_set; }
614
615 // Checks if object is in the collection set.
616 inline bool in_collection_set(oop obj) const;
617
618 // Checks if location is in the collection set. Can be interior pointer, not the oop itself.
619 inline bool in_collection_set_loc(void* loc) const;
620
621 // Evacuates object src. Returns the evacuated object, either evacuated
622 // by this thread, or by some other thread.
623 inline oop evacuate_object(oop src, Thread* thread);
624
625 // Call before/after evacuation.
626 inline void enter_evacuation(Thread* t);
627 inline void leave_evacuation(Thread* t);
628
629 // ---------- Helper functions
630 //
631 public:
632 template <class T>
633 inline void conc_update_with_forwarded(T* p);
634
635 template <class T>
636 inline void update_with_forwarded(T* p);
637
638 static inline oop cas_oop(oop n, narrowOop* addr, oop c);
639 static inline oop cas_oop(oop n, oop* addr, oop c);
640 static inline oop cas_oop(oop n, narrowOop* addr, narrowOop c);
641
642 void trash_humongous_region_at(ShenandoahHeapRegion *r);
643
644 private:
645 void trash_cset_regions();
646
647 // ---------- Testing helpers functions
648 //
649 private:
650 ShenandoahSharedFlag _inject_alloc_failure;
651
652 void try_inject_alloc_failure();
653 bool should_inject_alloc_failure();
654 };
655
656 #endif // SHARE_GC_SHENANDOAH_SHENANDOAHHEAP_HPP