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