1 /*
2 * Copyright (c) 2001, 2018, Oracle and/or its affiliates. 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
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7 * published by the Free Software Foundation.
8 *
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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).
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16 * 2 along with this work; if not, write to the Free Software Foundation,
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23 */
24
25 #ifndef SHARE_VM_GC_SHARED_COLLECTEDHEAP_HPP
26 #define SHARE_VM_GC_SHARED_COLLECTEDHEAP_HPP
27
28 #include "gc/shared/gcCause.hpp"
29 #include "gc/shared/gcWhen.hpp"
30 #include "memory/allocation.hpp"
31 #include "runtime/handles.hpp"
32 #include "runtime/perfData.hpp"
33 #include "runtime/safepoint.hpp"
34 #include "utilities/debug.hpp"
35 #include "utilities/events.hpp"
36 #include "utilities/formatBuffer.hpp"
37 #include "utilities/growableArray.hpp"
38
39 // A "CollectedHeap" is an implementation of a java heap for HotSpot. This
40 // is an abstract class: there may be many different kinds of heaps. This
41 // class defines the functions that a heap must implement, and contains
42 // infrastructure common to all heaps.
43
44 class AdaptiveSizePolicy;
45 class BarrierSet;
46 class CollectorPolicy;
47 class GCHeapSummary;
48 class GCTimer;
49 class GCTracer;
50 class GCMemoryManager;
51 class MemoryPool;
52 class MetaspaceSummary;
53 class SoftRefPolicy;
54 class Thread;
55 class ThreadClosure;
56 class VirtualSpaceSummary;
57 class WorkGang;
58 class nmethod;
59
60 class GCMessage : public FormatBuffer<1024> {
61 public:
62 bool is_before;
63
64 public:
65 GCMessage() {}
66 };
67
68 class CollectedHeap;
69
70 class GCHeapLog : public EventLogBase<GCMessage> {
71 private:
72 void log_heap(CollectedHeap* heap, bool before);
73
74 public:
75 GCHeapLog() : EventLogBase<GCMessage>("GC Heap History") {}
76
77 void log_heap_before(CollectedHeap* heap) {
78 log_heap(heap, true);
79 }
80 void log_heap_after(CollectedHeap* heap) {
81 log_heap(heap, false);
82 }
83 };
84
85 //
86 // CollectedHeap
87 // GenCollectedHeap
88 // SerialHeap
89 // CMSHeap
90 // G1CollectedHeap
91 // ParallelScavengeHeap
92 // ShenandoahHeap
93 // ZCollectedHeap
94 //
95 class CollectedHeap : public CHeapObj<mtInternal> {
96 friend class VMStructs;
97 friend class JVMCIVMStructs;
98 friend class IsGCActiveMark; // Block structured external access to _is_gc_active
99 friend class MemAllocator;
100
101 private:
102 #ifdef ASSERT
103 static int _fire_out_of_memory_count;
104 #endif
105
106 GCHeapLog* _gc_heap_log;
107
108 MemRegion _reserved;
109
110 protected:
111 bool _is_gc_active;
112
113 // Used for filler objects (static, but initialized in ctor).
114 static size_t _filler_array_max_size;
115
116 unsigned int _total_collections; // ... started
117 unsigned int _total_full_collections; // ... started
118 NOT_PRODUCT(volatile size_t _promotion_failure_alot_count;)
119 NOT_PRODUCT(volatile size_t _promotion_failure_alot_gc_number;)
120
121 // Reason for current garbage collection. Should be set to
122 // a value reflecting no collection between collections.
123 GCCause::Cause _gc_cause;
124 GCCause::Cause _gc_lastcause;
125 PerfStringVariable* _perf_gc_cause;
126 PerfStringVariable* _perf_gc_lastcause;
127
128 // Constructor
129 CollectedHeap();
130
131 // Create a new tlab. All TLAB allocations must go through this.
132 // To allow more flexible TLAB allocations min_size specifies
133 // the minimum size needed, while requested_size is the requested
134 // size based on ergonomics. The actually allocated size will be
135 // returned in actual_size.
136 virtual HeapWord* allocate_new_tlab(size_t min_size,
137 size_t requested_size,
138 size_t* actual_size);
139
140 // Accumulate statistics on all tlabs.
141 virtual void accumulate_statistics_all_tlabs();
142
143 // Reinitialize tlabs before resuming mutators.
144 virtual void resize_all_tlabs();
145
146 // Raw memory allocation facilities
147 // The obj and array allocate methods are covers for these methods.
148 // mem_allocate() should never be
149 // called to allocate TLABs, only individual objects.
150 virtual HeapWord* mem_allocate(size_t size,
151 bool* gc_overhead_limit_was_exceeded) = 0;
152
153 // Filler object utilities.
154 static inline size_t filler_array_hdr_size();
155 static inline size_t filler_array_min_size();
156
157 DEBUG_ONLY(static void fill_args_check(HeapWord* start, size_t words);)
158 DEBUG_ONLY(static void zap_filler_array(HeapWord* start, size_t words, bool zap = true);)
159
160 // Fill with a single array; caller must ensure filler_array_min_size() <=
161 // words <= filler_array_max_size().
162 static inline void fill_with_array(HeapWord* start, size_t words, bool zap = true);
163
164 // Fill with a single object (either an int array or a java.lang.Object).
165 static inline void fill_with_object_impl(HeapWord* start, size_t words, bool zap = true);
166
167 virtual void trace_heap(GCWhen::Type when, const GCTracer* tracer);
168
169 // Verification functions
170 virtual void check_for_non_bad_heap_word_value(HeapWord* addr, size_t size)
171 PRODUCT_RETURN;
172 debug_only(static void check_for_valid_allocation_state();)
173
174 public:
175 enum Name {
176 None,
177 Serial,
178 Parallel,
179 CMS,
180 G1,
181 Epsilon,
182 Z,
183 Shenandoah
184 };
185
186 static inline size_t filler_array_max_size() {
187 return _filler_array_max_size;
188 }
189
190 virtual Name kind() const = 0;
191
192 virtual const char* name() const = 0;
193
194 /**
195 * Returns JNI error code JNI_ENOMEM if memory could not be allocated,
196 * and JNI_OK on success.
197 */
198 virtual jint initialize() = 0;
199
200 // In many heaps, there will be a need to perform some initialization activities
201 // after the Universe is fully formed, but before general heap allocation is allowed.
202 // This is the correct place to place such initialization methods.
203 virtual void post_initialize();
204
205 // Stop any onging concurrent work and prepare for exit.
206 virtual void stop() {}
207
208 // Stop and resume concurrent GC threads interfering with safepoint operations
209 virtual void safepoint_synchronize_begin() {}
210 virtual void safepoint_synchronize_end() {}
211
212 void initialize_reserved_region(HeapWord *start, HeapWord *end);
213 MemRegion reserved_region() const { return _reserved; }
214 address base() const { return (address)reserved_region().start(); }
215
216 virtual size_t capacity() const = 0;
217 virtual size_t used() const = 0;
218
219 // Return "true" if the part of the heap that allocates Java
220 // objects has reached the maximal committed limit that it can
221 // reach, without a garbage collection.
222 virtual bool is_maximal_no_gc() const = 0;
223
224 // Support for java.lang.Runtime.maxMemory(): return the maximum amount of
225 // memory that the vm could make available for storing 'normal' java objects.
226 // This is based on the reserved address space, but should not include space
227 // that the vm uses internally for bookkeeping or temporary storage
228 // (e.g., in the case of the young gen, one of the survivor
229 // spaces).
230 virtual size_t max_capacity() const = 0;
231
232 // Returns "TRUE" if "p" points into the reserved area of the heap.
233 bool is_in_reserved(const void* p) const {
234 return _reserved.contains(p);
235 }
236
237 bool is_in_reserved_or_null(const void* p) const {
238 return p == NULL || is_in_reserved(p);
239 }
240
241 // Returns "TRUE" iff "p" points into the committed areas of the heap.
242 // This method can be expensive so avoid using it in performance critical
243 // code.
244 virtual bool is_in(const void* p) const = 0;
245
246 DEBUG_ONLY(bool is_in_or_null(const void* p) const { return p == NULL || is_in(p); })
247
248 // Let's define some terms: a "closed" subset of a heap is one that
249 //
250 // 1) contains all currently-allocated objects, and
251 //
252 // 2) is closed under reference: no object in the closed subset
253 // references one outside the closed subset.
254 //
255 // Membership in a heap's closed subset is useful for assertions.
256 // Clearly, the entire heap is a closed subset, so the default
257 // implementation is to use "is_in_reserved". But this may not be too
258 // liberal to perform useful checking. Also, the "is_in" predicate
259 // defines a closed subset, but may be too expensive, since "is_in"
260 // verifies that its argument points to an object head. The
261 // "closed_subset" method allows a heap to define an intermediate
262 // predicate, allowing more precise checking than "is_in_reserved" at
263 // lower cost than "is_in."
264
265 // One important case is a heap composed of disjoint contiguous spaces,
266 // such as the Garbage-First collector. Such heaps have a convenient
267 // closed subset consisting of the allocated portions of those
268 // contiguous spaces.
269
270 // Return "TRUE" iff the given pointer points into the heap's defined
271 // closed subset (which defaults to the entire heap).
272 virtual bool is_in_closed_subset(const void* p) const {
273 return is_in_reserved(p);
274 }
275
276 bool is_in_closed_subset_or_null(const void* p) const {
277 return p == NULL || is_in_closed_subset(p);
278 }
279
280 void set_gc_cause(GCCause::Cause v) {
281 if (UsePerfData) {
282 _gc_lastcause = _gc_cause;
283 _perf_gc_lastcause->set_value(GCCause::to_string(_gc_lastcause));
284 _perf_gc_cause->set_value(GCCause::to_string(v));
285 }
286 _gc_cause = v;
287 }
288 GCCause::Cause gc_cause() { return _gc_cause; }
289
290 virtual oop obj_allocate(Klass* klass, int size, TRAPS);
291 virtual oop array_allocate(Klass* klass, int size, int length, bool do_zero, TRAPS);
292 virtual oop class_allocate(Klass* klass, int size, TRAPS);
293
294 // Utilities for turning raw memory into filler objects.
295 //
296 // min_fill_size() is the smallest region that can be filled.
297 // fill_with_objects() can fill arbitrary-sized regions of the heap using
298 // multiple objects. fill_with_object() is for regions known to be smaller
299 // than the largest array of integers; it uses a single object to fill the
300 // region and has slightly less overhead.
301 static size_t min_fill_size() {
302 return size_t(align_object_size(oopDesc::header_size()));
303 }
304
305 static void fill_with_objects(HeapWord* start, size_t words, bool zap = true);
306
307 static void fill_with_object(HeapWord* start, size_t words, bool zap = true);
308 static void fill_with_object(MemRegion region, bool zap = true) {
309 fill_with_object(region.start(), region.word_size(), zap);
310 }
311 static void fill_with_object(HeapWord* start, HeapWord* end, bool zap = true) {
312 fill_with_object(start, pointer_delta(end, start), zap);
313 }
314
315 virtual void fill_with_dummy_object(HeapWord* start, HeapWord* end, bool zap);
316
317 // Return the address "addr" aligned by "alignment_in_bytes" if such
318 // an address is below "end". Return NULL otherwise.
319 inline static HeapWord* align_allocation_or_fail(HeapWord* addr,
320 HeapWord* end,
321 unsigned short alignment_in_bytes);
322
323 // Some heaps may offer a contiguous region for shared non-blocking
324 // allocation, via inlined code (by exporting the address of the top and
325 // end fields defining the extent of the contiguous allocation region.)
326
327 // This function returns "true" iff the heap supports this kind of
328 // allocation. (Default is "no".)
329 virtual bool supports_inline_contig_alloc() const {
330 return false;
331 }
332 // These functions return the addresses of the fields that define the
333 // boundaries of the contiguous allocation area. (These fields should be
334 // physically near to one another.)
335 virtual HeapWord* volatile* top_addr() const {
336 guarantee(false, "inline contiguous allocation not supported");
337 return NULL;
338 }
339 virtual HeapWord** end_addr() const {
340 guarantee(false, "inline contiguous allocation not supported");
341 return NULL;
342 }
343
344 // Some heaps may be in an unparseable state at certain times between
345 // collections. This may be necessary for efficient implementation of
346 // certain allocation-related activities. Calling this function before
347 // attempting to parse a heap ensures that the heap is in a parsable
348 // state (provided other concurrent activity does not introduce
349 // unparsability). It is normally expected, therefore, that this
350 // method is invoked with the world stopped.
351 // NOTE: if you override this method, make sure you call
352 // super::ensure_parsability so that the non-generational
353 // part of the work gets done. See implementation of
354 // CollectedHeap::ensure_parsability and, for instance,
355 // that of GenCollectedHeap::ensure_parsability().
356 // The argument "retire_tlabs" controls whether existing TLABs
357 // are merely filled or also retired, thus preventing further
358 // allocation from them and necessitating allocation of new TLABs.
359 virtual void ensure_parsability(bool retire_tlabs);
360
361 // Section on thread-local allocation buffers (TLABs)
362 // If the heap supports thread-local allocation buffers, it should override
363 // the following methods:
364 // Returns "true" iff the heap supports thread-local allocation buffers.
365 // The default is "no".
366 virtual bool supports_tlab_allocation() const = 0;
367
368 // The amount of space available for thread-local allocation buffers.
369 virtual size_t tlab_capacity(Thread *thr) const = 0;
370
371 // The amount of used space for thread-local allocation buffers for the given thread.
372 virtual size_t tlab_used(Thread *thr) const = 0;
373
374 virtual size_t max_tlab_size() const;
375
376 // An estimate of the maximum allocation that could be performed
377 // for thread-local allocation buffers without triggering any
378 // collection or expansion activity.
379 virtual size_t unsafe_max_tlab_alloc(Thread *thr) const {
380 guarantee(false, "thread-local allocation buffers not supported");
381 return 0;
382 }
383
384 // Perform a collection of the heap; intended for use in implementing
385 // "System.gc". This probably implies as full a collection as the
386 // "CollectedHeap" supports.
387 virtual void collect(GCCause::Cause cause) = 0;
388
389 // Perform a full collection
390 virtual void do_full_collection(bool clear_all_soft_refs) = 0;
391
392 // This interface assumes that it's being called by the
393 // vm thread. It collects the heap assuming that the
394 // heap lock is already held and that we are executing in
395 // the context of the vm thread.
396 virtual void collect_as_vm_thread(GCCause::Cause cause);
397
398 virtual MetaWord* satisfy_failed_metadata_allocation(ClassLoaderData* loader_data,
399 size_t size,
400 Metaspace::MetadataType mdtype);
401
402 // Returns "true" iff there is a stop-world GC in progress. (I assume
403 // that it should answer "false" for the concurrent part of a concurrent
404 // collector -- dld).
405 bool is_gc_active() const { return _is_gc_active; }
406
407 // Total number of GC collections (started)
408 unsigned int total_collections() const { return _total_collections; }
409 unsigned int total_full_collections() const { return _total_full_collections;}
410
411 // Increment total number of GC collections (started)
412 // Should be protected but used by PSMarkSweep - cleanup for 1.4.2
413 void increment_total_collections(bool full = false) {
414 _total_collections++;
415 if (full) {
416 increment_total_full_collections();
417 }
418 }
419
420 void increment_total_full_collections() { _total_full_collections++; }
421
422 // Return the CollectorPolicy for the heap
423 virtual CollectorPolicy* collector_policy() const = 0;
424
425 // Return the SoftRefPolicy for the heap;
426 virtual SoftRefPolicy* soft_ref_policy() = 0;
427
428 virtual GrowableArray<GCMemoryManager*> memory_managers() = 0;
429 virtual GrowableArray<MemoryPool*> memory_pools() = 0;
430
431 // Iterate over all objects, calling "cl.do_object" on each.
432 virtual void object_iterate(ObjectClosure* cl) = 0;
433
434 // Similar to object_iterate() except iterates only
435 // over live objects.
436 virtual void safe_object_iterate(ObjectClosure* cl) = 0;
437
438 // NOTE! There is no requirement that a collector implement these
439 // functions.
440 //
441 // A CollectedHeap is divided into a dense sequence of "blocks"; that is,
442 // each address in the (reserved) heap is a member of exactly
443 // one block. The defining characteristic of a block is that it is
444 // possible to find its size, and thus to progress forward to the next
445 // block. (Blocks may be of different sizes.) Thus, blocks may
446 // represent Java objects, or they might be free blocks in a
447 // free-list-based heap (or subheap), as long as the two kinds are
448 // distinguishable and the size of each is determinable.
449
450 // Returns the address of the start of the "block" that contains the
451 // address "addr". We say "blocks" instead of "object" since some heaps
452 // may not pack objects densely; a chunk may either be an object or a
453 // non-object.
454 virtual HeapWord* block_start(const void* addr) const = 0;
455
456 // Requires "addr" to be the start of a chunk, and returns its size.
457 // "addr + size" is required to be the start of a new chunk, or the end
458 // of the active area of the heap.
459 virtual size_t block_size(const HeapWord* addr) const = 0;
460
461 // Requires "addr" to be the start of a block, and returns "TRUE" iff
462 // the block is an object.
463 virtual bool block_is_obj(const HeapWord* addr) const = 0;
464
465 // Returns the longest time (in ms) that has elapsed since the last
466 // time that any part of the heap was examined by a garbage collection.
467 virtual jlong millis_since_last_gc() = 0;
468
469 // Perform any cleanup actions necessary before allowing a verification.
470 virtual void prepare_for_verify() = 0;
471
472 // Generate any dumps preceding or following a full gc
473 private:
474 void full_gc_dump(GCTimer* timer, bool before);
475
476 virtual void initialize_serviceability() = 0;
477
478 public:
479 void pre_full_gc_dump(GCTimer* timer);
480 void post_full_gc_dump(GCTimer* timer);
481
482 virtual VirtualSpaceSummary create_heap_space_summary();
483 GCHeapSummary create_heap_summary();
484
485 MetaspaceSummary create_metaspace_summary();
486
487 // Print heap information on the given outputStream.
488 virtual void print_on(outputStream* st) const = 0;
489 // The default behavior is to call print_on() on tty.
490 virtual void print() const {
491 print_on(tty);
492 }
493 // Print more detailed heap information on the given
494 // outputStream. The default behavior is to call print_on(). It is
495 // up to each subclass to override it and add any additional output
496 // it needs.
497 virtual void print_extended_on(outputStream* st) const {
498 print_on(st);
499 }
500
501 virtual void print_on_error(outputStream* st) const;
502
503 // Print all GC threads (other than the VM thread)
504 // used by this heap.
505 virtual void print_gc_threads_on(outputStream* st) const = 0;
506 // The default behavior is to call print_gc_threads_on() on tty.
507 void print_gc_threads() {
508 print_gc_threads_on(tty);
509 }
510 // Iterator for all GC threads (other than VM thread)
511 virtual void gc_threads_do(ThreadClosure* tc) const = 0;
512
513 // Print any relevant tracing info that flags imply.
514 // Default implementation does nothing.
515 virtual void print_tracing_info() const = 0;
516
517 void print_heap_before_gc();
518 void print_heap_after_gc();
519
520 // An object is scavengable if its location may move during a scavenge.
521 // (A scavenge is a GC which is not a full GC.)
522 virtual bool is_scavengable(oop obj) = 0;
523 // Registering and unregistering an nmethod (compiled code) with the heap.
524 // Override with specific mechanism for each specialized heap type.
525 virtual void register_nmethod(nmethod* nm) {}
526 virtual void unregister_nmethod(nmethod* nm) {}
527 virtual void verify_nmethod(nmethod* nmethod) {}
528
529 void trace_heap_before_gc(const GCTracer* gc_tracer);
530 void trace_heap_after_gc(const GCTracer* gc_tracer);
531
532 // Heap verification
533 virtual void verify(VerifyOption option) = 0;
534
535 // Return true if concurrent phase control (via
536 // request_concurrent_phase_control) is supported by this collector.
537 // The default implementation returns false.
538 virtual bool supports_concurrent_phase_control() const;
539
540 // Return a NULL terminated array of concurrent phase names provided
541 // by this collector. Supports Whitebox testing. These are the
542 // names recognized by request_concurrent_phase(). The default
543 // implementation returns an array of one NULL element.
544 virtual const char* const* concurrent_phases() const;
545
546 // Request the collector enter the indicated concurrent phase, and
547 // wait until it does so. Supports WhiteBox testing. Only one
548 // request may be active at a time. Phases are designated by name;
549 // the set of names and their meaning is GC-specific. Once the
550 // requested phase has been reached, the collector will attempt to
551 // avoid transitioning to a new phase until a new request is made.
552 // [Note: A collector might not be able to remain in a given phase.
553 // For example, a full collection might cancel an in-progress
554 // concurrent collection.]
555 //
556 // Returns true when the phase is reached. Returns false for an
557 // unknown phase. The default implementation returns false.
558 virtual bool request_concurrent_phase(const char* phase);
559
560 // Provides a thread pool to SafepointSynchronize to use
561 // for parallel safepoint cleanup.
562 // GCs that use a GC worker thread pool may want to share
563 // it for use during safepoint cleanup. This is only possible
564 // if the GC can pause and resume concurrent work (e.g. G1
565 // concurrent marking) for an intermittent non-GC safepoint.
566 // If this method returns NULL, SafepointSynchronize will
567 // perform cleanup tasks serially in the VMThread.
568 virtual WorkGang* get_safepoint_workers() { return NULL; }
569
570 // Support for object pinning. This is used by JNI Get*Critical()
571 // and Release*Critical() family of functions. If supported, the GC
572 // must guarantee that pinned objects never move.
573 virtual bool supports_object_pinning() const;
574 virtual oop pin_object(JavaThread* thread, oop obj);
575 virtual void unpin_object(JavaThread* thread, oop obj);
576
577 // Deduplicate the string, iff the GC supports string deduplication.
578 virtual void deduplicate_string(oop str);
579
580 virtual bool is_oop(oop object) const;
581
582 // Non product verification and debugging.
583 #ifndef PRODUCT
584 // Support for PromotionFailureALot. Return true if it's time to cause a
585 // promotion failure. The no-argument version uses
586 // this->_promotion_failure_alot_count as the counter.
587 bool promotion_should_fail(volatile size_t* count);
588 bool promotion_should_fail();
589
590 // Reset the PromotionFailureALot counters. Should be called at the end of a
591 // GC in which promotion failure occurred.
592 void reset_promotion_should_fail(volatile size_t* count);
593 void reset_promotion_should_fail();
594 #endif // #ifndef PRODUCT
595
596 #ifdef ASSERT
597 static int fired_fake_oom() {
598 return (CIFireOOMAt > 1 && _fire_out_of_memory_count >= CIFireOOMAt);
599 }
600 #endif
601 };
602
603 // Class to set and reset the GC cause for a CollectedHeap.
604
605 class GCCauseSetter : StackObj {
606 CollectedHeap* _heap;
607 GCCause::Cause _previous_cause;
608 public:
609 GCCauseSetter(CollectedHeap* heap, GCCause::Cause cause) {
610 _heap = heap;
611 _previous_cause = _heap->gc_cause();
612 _heap->set_gc_cause(cause);
613 }
614
615 ~GCCauseSetter() {
616 _heap->set_gc_cause(_previous_cause);
617 }
618 };
619
620 #endif // SHARE_VM_GC_SHARED_COLLECTEDHEAP_HPP