1 /*
2 * Copyright (c) 2013, 2020, Red Hat, Inc. All rights reserved.
3 *
4 * This code is free software; you can redistribute it and/or modify it
5 * under the terms of the GNU General Public License version 2 only, as
6 * published by the Free Software Foundation.
7 *
8 * This code is distributed in the hope that it will be useful, but WITHOUT
9 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
10 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
11 * version 2 for more details (a copy is included in the LICENSE file that
12 * accompanied this code).
13 *
14 * You should have received a copy of the GNU General Public License version
15 * 2 along with this work; if not, write to the Free Software Foundation,
16 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
17 *
18 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
19 * or visit www.oracle.com if you need additional information or have any
20 * questions.
21 *
22 */
23
24 #ifndef SHARE_VM_GC_SHENANDOAH_SHENANDOAHHEAP_HPP
25 #define SHARE_VM_GC_SHENANDOAH_SHENANDOAHHEAP_HPP
26
27 #include "gc_implementation/shared/markBitMap.hpp"
28 #include "gc_implementation/shenandoah/shenandoahAsserts.hpp"
29 #include "gc_implementation/shenandoah/shenandoahAllocRequest.hpp"
30 #include "gc_implementation/shenandoah/shenandoahLock.hpp"
31 #include "gc_implementation/shenandoah/shenandoahEvacOOMHandler.hpp"
32 #include "gc_implementation/shenandoah/shenandoahPadding.hpp"
33 #include "gc_implementation/shenandoah/shenandoahSharedVariables.hpp"
34
35 class ConcurrentGCTimer;
36
37 class ShenandoahCollectionSet;
38 class ShenandoahCollectorPolicy;
39 class ShenandoahConcurrentMark;
40 class ShenandoahControlThread;
41 class ShenandoahGCSession;
42 class ShenandoahGCStateResetter;
43 class ShenandoahFreeSet;
44 class ShenandoahHeapRegion;
45 class ShenandoahHeapRegionClosure;
46 class ShenandoahMarkCompact;
47 class ShenandoahMonitoringSupport;
48 class ShenandoahHeuristics;
49 class ShenandoahMarkingContext;
50 class ShenandoahMode;
51 class ShenandoahPhaseTimings;
52 class ShenandoahPacer;
53 class ShenandoahVerifier;
54 class ShenandoahWorkGang;
55 class VMStructs;
56
57 // Used for buffering per-region liveness data.
58 // Needed since ShenandoahHeapRegion uses atomics to update liveness.
59 // The ShenandoahHeap array has max-workers elements, each of which is an array of
60 // uint16_t * max_regions. The choice of uint16_t is not accidental:
61 // there is a tradeoff between static/dynamic footprint that translates
62 // into cache pressure (which is already high during marking), and
63 // too many atomic updates. uint32_t is too large, uint8_t is too small.
64 typedef uint16_t ShenandoahLiveData;
65 #define SHENANDOAH_LIVEDATA_MAX ((ShenandoahLiveData)-1)
66
67 class ShenandoahRegionIterator : public StackObj {
68 private:
69 ShenandoahHeap* _heap;
70
71 shenandoah_padding(0);
72 volatile jint _index;
73 shenandoah_padding(1);
74
75 // No implicit copying: iterators should be passed by reference to capture the state
76 ShenandoahRegionIterator(const ShenandoahRegionIterator& that);
77 ShenandoahRegionIterator& operator=(const ShenandoahRegionIterator& o);
78
79 public:
80 ShenandoahRegionIterator();
81 ShenandoahRegionIterator(ShenandoahHeap* heap);
82
83 // Reset iterator to default state
84 void reset();
85
86 // Returns next region, or NULL if there are no more regions.
87 // This is multi-thread-safe.
88 inline ShenandoahHeapRegion* next();
89
90 // This is *not* MT safe. However, in the absence of multithreaded access, it
91 // can be used to determine if there is more work to do.
92 bool has_next() const;
93 };
94
95 class ShenandoahHeapRegionClosure : public StackObj {
96 public:
97 virtual void heap_region_do(ShenandoahHeapRegion* r) = 0;
98 virtual bool is_thread_safe() { return false; }
99 };
100
101 typedef ShenandoahLock ShenandoahHeapLock;
102 typedef ShenandoahLocker ShenandoahHeapLocker;
103
104 // Shenandoah GC is low-pause concurrent GC that uses Brooks forwarding pointers
105 // to encode forwarding data. See BrooksPointer for details on forwarding data encoding.
106 // See ShenandoahControlThread for GC cycle structure.
107 //
108 class ShenandoahHeap : public SharedHeap {
109 friend class ShenandoahAsserts;
110 friend class VMStructs;
111 friend class ShenandoahGCSession;
112 friend class ShenandoahGCStateResetter;
113 friend class ShenandoahSafepoint;
114
115 // ---------- Locks that guard important data structures in Heap
116 //
117 private:
118 ShenandoahHeapLock _lock;
119
120 public:
121 ShenandoahHeapLock* lock() {
122 return &_lock;
123 }
124
125 // ---------- Initialization, termination, identification, printing routines
126 //
127 private:
128 static ShenandoahHeap* _heap;
129
130 public:
131 static ShenandoahHeap* heap();
132 static size_t conservative_max_heap_alignment();
133
134 const char* name() const { return "Shenandoah"; }
135 ShenandoahHeap::Name kind() const { return CollectedHeap::ShenandoahHeap; }
136
137 ShenandoahHeap(ShenandoahCollectorPolicy* policy);
138 jint initialize();
139 void post_initialize();
140 void initialize_heuristics();
141
142 void print_on(outputStream* st) const;
143 void print_extended_on(outputStream *st) const;
144 void print_tracing_info() const;
145 void print_gc_threads_on(outputStream* st) const;
146 void print_heap_regions_on(outputStream* st) const;
147
148 void stop();
149
150 void prepare_for_verify();
151 void verify(bool silent, VerifyOption vo);
152
153 // ---------- Heap counters and metrics
154 //
155 private:
156 size_t _initial_size;
157 size_t _minimum_size;
158 volatile size_t _soft_max_size;
159 shenandoah_padding(0);
160 volatile jlong _used;
161 volatile size_t _committed;
162 volatile jlong _bytes_allocated_since_gc_start;
163 shenandoah_padding(1);
164
165 public:
166 void increase_used(size_t bytes);
167 void decrease_used(size_t bytes);
168 void set_used(size_t bytes);
169
170 void increase_committed(size_t bytes);
171 void decrease_committed(size_t bytes);
172 void increase_allocated(size_t bytes);
173
174 size_t bytes_allocated_since_gc_start();
175 void reset_bytes_allocated_since_gc_start();
176
177 size_t min_capacity() const;
178 size_t max_capacity() const;
179 size_t soft_max_capacity() const;
180 size_t initial_capacity() const;
181 size_t capacity() const;
182 size_t used() const;
183 size_t committed() const;
184
185 void set_soft_max_capacity(size_t v);
186
187 // ---------- Workers handling
188 //
189 private:
190 uint _max_workers;
191
192 public:
193 uint max_workers();
194 void assert_gc_workers(uint nworker) NOT_DEBUG_RETURN;
195
196 ShenandoahWorkGang* workers() const;
197
198 void gc_threads_do(ThreadClosure* tcl) const;
199
200 // ---------- Heap regions handling machinery
201 //
202 private:
203 MemRegion _heap_region;
204 bool _heap_region_special;
205 size_t _num_regions;
206 ShenandoahHeapRegion** _regions;
207 ShenandoahRegionIterator _update_refs_iterator;
208
209 public:
210 inline size_t num_regions() const { return _num_regions; }
211 inline bool is_heap_region_special() { return _heap_region_special; }
212
213 inline ShenandoahHeapRegion* const heap_region_containing(const void* addr) const;
214 inline size_t heap_region_index_containing(const void* addr) const;
215
216 inline ShenandoahHeapRegion* const get_region(size_t region_idx) const;
217
218 void heap_region_iterate(ShenandoahHeapRegionClosure* blk) const;
219 void parallel_heap_region_iterate(ShenandoahHeapRegionClosure* blk) const;
220
221 // ---------- GC state machinery
222 //
223 // GC state describes the important parts of collector state, that may be
224 // used to make barrier selection decisions in the native and generated code.
225 // Multiple bits can be set at once.
226 //
227 // Important invariant: when GC state is zero, the heap is stable, and no barriers
228 // are required.
229 //
230 public:
231 enum GCStateBitPos {
232 // Heap has forwarded objects: need RB, ACMP, CAS barriers.
233 HAS_FORWARDED_BITPOS = 0,
234
235 // Heap is under marking: needs SATB barriers.
236 MARKING_BITPOS = 1,
237
238 // Heap is under evacuation: needs WB barriers. (Set together with UNSTABLE)
239 EVACUATION_BITPOS = 2,
240
241 // Heap is under updating: needs SVRB/SVWB barriers.
242 UPDATEREFS_BITPOS = 3,
243 };
244
245 enum GCState {
246 STABLE = 0,
247 HAS_FORWARDED = 1 << HAS_FORWARDED_BITPOS,
248 MARKING = 1 << MARKING_BITPOS,
249 EVACUATION = 1 << EVACUATION_BITPOS,
250 UPDATEREFS = 1 << UPDATEREFS_BITPOS,
251 };
252
253 private:
254 ShenandoahSharedBitmap _gc_state;
255 ShenandoahSharedFlag _degenerated_gc_in_progress;
256 ShenandoahSharedFlag _full_gc_in_progress;
257 ShenandoahSharedFlag _full_gc_move_in_progress;
258 ShenandoahSharedFlag _progress_last_gc;
259
260 void set_gc_state_mask(uint mask, bool value);
261
262 public:
263 char gc_state();
264 static address gc_state_addr();
265
266 void set_concurrent_mark_in_progress(bool in_progress);
267 void set_evacuation_in_progress(bool in_progress);
268 void set_update_refs_in_progress(bool in_progress);
269 void set_degenerated_gc_in_progress(bool in_progress);
270 void set_full_gc_in_progress(bool in_progress);
271 void set_full_gc_move_in_progress(bool in_progress);
272 void set_has_forwarded_objects(bool cond);
273
274 inline bool is_stable() const;
275 inline bool is_idle() const;
276 inline bool is_concurrent_mark_in_progress() const;
277 inline bool is_update_refs_in_progress() const;
278 inline bool is_evacuation_in_progress() const;
279 inline bool is_degenerated_gc_in_progress() const;
280 inline bool is_full_gc_in_progress() const;
281 inline bool is_full_gc_move_in_progress() const;
282 inline bool has_forwarded_objects() const;
283 inline bool is_gc_in_progress_mask(uint mask) const;
284
285 // ---------- GC cancellation and degeneration machinery
286 //
287 // Cancelled GC flag is used to notify concurrent phases that they should terminate.
288 //
289 public:
290 enum ShenandoahDegenPoint {
291 _degenerated_unset,
292 _degenerated_outside_cycle,
293 _degenerated_mark,
294 _degenerated_evac,
295 _degenerated_updaterefs,
296 _DEGENERATED_LIMIT
297 };
298
299 static const char* degen_point_to_string(ShenandoahDegenPoint point) {
300 switch (point) {
301 case _degenerated_unset:
302 return "<UNSET>";
303 case _degenerated_outside_cycle:
304 return "Outside of Cycle";
305 case _degenerated_mark:
306 return "Mark";
307 case _degenerated_evac:
308 return "Evacuation";
309 case _degenerated_updaterefs:
310 return "Update Refs";
311 default:
312 ShouldNotReachHere();
313 return "ERROR";
314 }
315 };
316
317 private:
318 ShenandoahSharedFlag _cancelled_gc;
319 inline bool try_cancel_gc();
320
321 public:
322 static address cancelled_gc_addr();
323
324 inline bool cancelled_gc() const;
325
326 inline void clear_cancelled_gc();
327
328 void cancel_gc(GCCause::Cause cause);
329
330 // ---------- GC operations entry points
331 //
332 public:
333 // Entry points to STW GC operations, these cause a related safepoint, that then
334 // call the entry method below
335 void vmop_entry_init_mark();
336 void vmop_entry_final_mark();
337 void vmop_entry_init_updaterefs();
338 void vmop_entry_final_updaterefs();
339 void vmop_entry_full(GCCause::Cause cause);
340 void vmop_degenerated(ShenandoahDegenPoint point);
341
342 // Entry methods to normally STW GC operations. These set up logging, monitoring
343 // and workers for net VM operation
344 void entry_init_mark();
345 void entry_final_mark();
346 void entry_init_updaterefs();
347 void entry_final_updaterefs();
348 void entry_full(GCCause::Cause cause);
349 void entry_degenerated(int point);
350
351 // Entry methods to normally concurrent GC operations. These set up logging, monitoring
352 // for concurrent operation.
353 void entry_reset();
354 void entry_mark();
355 void entry_preclean();
356 void entry_cleanup_early();
357 void entry_evac();
358 void entry_updaterefs();
359 void entry_cleanup_complete();
360 void entry_uncommit(double shrink_before, size_t shrink_until);
361
362 private:
363 // Actual work for the phases
364 void op_init_mark();
365 void op_final_mark();
366 void op_init_updaterefs();
367 void op_final_updaterefs();
368 void op_full(GCCause::Cause cause);
369 void op_degenerated(ShenandoahDegenPoint point);
370 void op_degenerated_fail();
371 void op_degenerated_futile();
372
373 void op_reset();
374 void op_mark();
375 void op_preclean();
376 void op_cleanup_early();
377 void op_conc_evac();
378 void op_stw_evac();
379 void op_updaterefs();
380 void op_cleanup_complete();
381 void op_uncommit(double shrink_before, size_t shrink_until);
382
383 // Messages for GC trace event, they have to be immortal for
384 // passing around the logging/tracing systems
385 const char* init_mark_event_message() const;
386 const char* final_mark_event_message() const;
387 const char* conc_mark_event_message() const;
388 const char* degen_event_message(ShenandoahDegenPoint point) const;
389
390 // ---------- GC subsystems
391 //
392 private:
393 ShenandoahControlThread* _control_thread;
394 ShenandoahCollectorPolicy* _shenandoah_policy;
395 ShenandoahMode* _gc_mode;
396 ShenandoahHeuristics* _heuristics;
397 ShenandoahFreeSet* _free_set;
398 ShenandoahConcurrentMark* _scm;
399 ShenandoahMarkCompact* _full_gc;
400 ShenandoahPacer* _pacer;
401 ShenandoahVerifier* _verifier;
402
403 ShenandoahPhaseTimings* _phase_timings;
404
405 ShenandoahControlThread* control_thread() { return _control_thread; }
406 ShenandoahMarkCompact* full_gc() { return _full_gc; }
407
408 public:
409 ShenandoahCollectorPolicy* shenandoah_policy() const { return _shenandoah_policy; }
410 ShenandoahHeuristics* heuristics() const { return _heuristics; }
411 ShenandoahFreeSet* free_set() const { return _free_set; }
412 ShenandoahConcurrentMark* concurrent_mark() { return _scm; }
413 ShenandoahPacer* pacer() const { return _pacer; }
414
415 ShenandoahPhaseTimings* phase_timings() const { return _phase_timings; }
416
417 ShenandoahVerifier* verifier();
418
419 // ---------- VM subsystem bindings
420 //
421 private:
422 ShenandoahMonitoringSupport* _monitoring_support;
423 ConcurrentGCTimer* _gc_timer;
424
425 public:
426 ShenandoahMonitoringSupport* monitoring_support() { return _monitoring_support; }
427
428 GCTracer* tracer();
429 GCTimer* gc_timer() const;
430 CollectorPolicy* collector_policy() const;
431
432 // ---------- Reference processing
433 //
434 private:
435 ReferenceProcessor* _ref_processor;
436 ShenandoahSharedFlag _process_references;
437
438 void ref_processing_init();
439
440 public:
441 ReferenceProcessor* ref_processor() { return _ref_processor;}
442 void set_process_references(bool pr);
443 bool process_references() const;
444
445 // ---------- Class Unloading
446 //
447 private:
448 ShenandoahSharedFlag _unload_classes;
449
450 public:
451 void set_unload_classes(bool uc);
452 bool unload_classes() const;
453
454 // Delete entries for dead interned string and clean up unreferenced symbols
455 // in symbol table, possibly in parallel.
456 void unload_classes_and_cleanup_tables(bool full_gc);
457
458 // ---------- Generic interface hooks
459 // Minor things that super-interface expects us to implement to play nice with
460 // the rest of runtime. Some of the things here are not required to be implemented,
461 // and can be stubbed out.
462 //
463 public:
464 AdaptiveSizePolicy* size_policy() shenandoah_not_implemented_return(NULL);
465 bool is_maximal_no_gc() const shenandoah_not_implemented_return(false);
466
467 bool is_in(const void* p) const;
468
469 // All objects can potentially move
470 bool is_scavengable(const void* addr) { return true; }
471
472 void collect(GCCause::Cause cause);
473 void do_full_collection(bool clear_all_soft_refs);
474
475 // Used for parsing heap during error printing
476 HeapWord* block_start(const void* addr) const;
477 size_t block_size(const HeapWord* addr) const;
478 bool block_is_obj(const HeapWord* addr) const;
479
480 // Used for native heap walkers: heap dumpers, mostly
481 void object_iterate(ObjectClosure* cl);
482 void safe_object_iterate(ObjectClosure* cl);
483 void space_iterate(SpaceClosure* scl) shenandoah_not_implemented;
484 void oop_iterate(ExtendedOopClosure* cl);
485 Space* space_containing(const void* oop) const shenandoah_not_implemented_return(NULL);
486
487 // Used by RMI
488 jlong millis_since_last_gc();
489
490 bool can_elide_tlab_store_barriers() const { return true; }
491 oop new_store_pre_barrier(JavaThread* thread, oop new_obj) { return new_obj; }
492 bool can_elide_initializing_store_barrier(oop new_obj) { return true; }
493 bool card_mark_must_follow_store() const { return false; }
494
495 bool is_in_partial_collection(const void* p) shenandoah_not_implemented_return(false);
496 bool supports_heap_inspection() const { return true; }
497
498 void gc_prologue(bool b);
499 void gc_epilogue(bool b);
500
501 void acquire_pending_refs_lock();
502 void release_pending_refs_lock();
503
504 // ---------- Code roots handling hooks
505 //
506 public:
507 void register_nmethod(nmethod* nm);
508 void unregister_nmethod(nmethod* nm);
509
510 // ---------- Pinning hooks
511 //
512 public:
513 // Shenandoah supports per-object (per-region) pinning
514 bool supports_object_pinning() const { return true; }
515
516 oop pin_object(JavaThread* thread, oop obj);
517 void unpin_object(JavaThread* thread, oop obj);
518
519 void sync_pinned_region_status();
520 void assert_pinned_region_status() NOT_DEBUG_RETURN;
521
522 // ---------- Allocation support
523 //
524 private:
525 HeapWord* allocate_memory_under_lock(ShenandoahAllocRequest& request, bool& in_new_region);
526 inline HeapWord* allocate_from_gclab(Thread* thread, size_t size);
527 HeapWord* allocate_from_gclab_slow(Thread* thread, size_t size);
528 HeapWord* allocate_new_gclab(size_t min_size, size_t word_size, size_t* actual_size);
529
530 public:
531 HeapWord* allocate_memory(ShenandoahAllocRequest& request);
532 HeapWord* mem_allocate(size_t size, bool* what);
533
534 void notify_mutator_alloc_words(size_t words, bool waste);
535
536 // Shenandoah supports TLAB allocation
537 bool supports_tlab_allocation() const { return true; }
538
539 HeapWord* allocate_new_tlab(size_t word_size);
540 size_t tlab_capacity(Thread *thr) const;
541 size_t unsafe_max_tlab_alloc(Thread *thread) const;
542 size_t max_tlab_size() const;
543 size_t tlab_used(Thread* ignored) const;
544
545 void resize_tlabs();
546 void resize_all_tlabs();
547
548 void accumulate_statistics_tlabs();
549 void accumulate_statistics_all_gclabs();
550
551 void make_parsable(bool retire_tlabs);
552 void ensure_parsability(bool retire_tlabs);
553
554 // ---------- Marking support
555 //
556 private:
557 ShenandoahMarkingContext* _marking_context;
558 MemRegion _bitmap_region;
559 MemRegion _aux_bitmap_region;
560 MarkBitMap _verification_bit_map;
561 MarkBitMap _aux_bit_map;
562
563 size_t _bitmap_size;
564 size_t _bitmap_regions_per_slice;
565 size_t _bitmap_bytes_per_slice;
566
567 size_t _pretouch_heap_page_size;
568 size_t _pretouch_bitmap_page_size;
569
570 bool _bitmap_region_special;
571 bool _aux_bitmap_region_special;
572
573 ShenandoahLiveData** _liveness_cache;
574
575 public:
576 inline ShenandoahMarkingContext* complete_marking_context() const;
577 inline ShenandoahMarkingContext* marking_context() const;
578 inline void mark_complete_marking_context();
579 inline void mark_incomplete_marking_context();
580
581 template<class T>
582 inline void marked_object_iterate(ShenandoahHeapRegion* region, T* cl);
583
584 template<class T>
585 inline void marked_object_iterate(ShenandoahHeapRegion* region, T* cl, HeapWord* limit);
586
587 template<class T>
588 inline void marked_object_oop_iterate(ShenandoahHeapRegion* region, T* cl, HeapWord* limit);
589
590 void reset_mark_bitmap();
591
592 // SATB barriers hooks
593 inline bool requires_marking(const void* entry) const;
594 void force_satb_flush_all_threads();
595
596 // Support for bitmap uncommits
597 bool commit_bitmap_slice(ShenandoahHeapRegion *r);
598 bool uncommit_bitmap_slice(ShenandoahHeapRegion *r);
599 bool is_bitmap_slice_committed(ShenandoahHeapRegion* r, bool skip_self = false);
600
601 // Liveness caching support
602 ShenandoahLiveData* get_liveness_cache(uint worker_id);
603 void flush_liveness_cache(uint worker_id);
604
605 size_t pretouch_heap_page_size() { return _pretouch_heap_page_size; }
606
607 // ---------- Evacuation support
608 //
609 private:
610 ShenandoahCollectionSet* _collection_set;
611 ShenandoahEvacOOMHandler _oom_evac_handler;
612
613 void evacuate_and_update_roots();
614
615 public:
616 static address in_cset_fast_test_addr();
617
618 ShenandoahCollectionSet* collection_set() const { return _collection_set; }
619
620 // Checks if object is in the collection set.
621 inline bool in_collection_set(oop obj) const;
622
623 // Checks if location is in the collection set. Can be interior pointer, not the oop itself.
624 inline bool in_collection_set_loc(void* loc) const;
625
626 // Evacuates object src. Returns the evacuated object, either evacuated
627 // by this thread, or by some other thread.
628 inline oop evacuate_object(oop src, Thread* thread);
629
630 // Call before/after evacuation.
631 void enter_evacuation();
632 void leave_evacuation();
633
634 // ---------- Helper functions
635 //
636 public:
637 template <class T>
638 inline oop evac_update_with_forwarded(T* p);
639
640 template <class T>
641 inline oop maybe_update_with_forwarded(T* p);
642
643 template <class T>
644 inline oop maybe_update_with_forwarded_not_null(T* p, oop obj);
645
646 template <class T>
647 inline oop update_with_forwarded_not_null(T* p, oop obj);
648
649 static inline oop cas_oop(oop n, narrowOop* addr, oop c);
650 static inline oop cas_oop(oop n, oop* addr, oop c);
651 static inline oop cas_oop(oop n, narrowOop* addr, narrowOop c);
652
653 void trash_humongous_region_at(ShenandoahHeapRegion *r);
654
655 void complete_marking();
656
657 private:
658 void trash_cset_regions();
659 void update_heap_references(bool concurrent);
660
661 // ---------- Testing helpers functions
662 //
663 private:
664 ShenandoahSharedFlag _inject_alloc_failure;
665
666 void try_inject_alloc_failure();
667 bool should_inject_alloc_failure();
668 };
669
670 #endif // SHARE_VM_GC_SHENANDOAH_SHENANDOAHHEAP_HPP