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
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.
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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 "services/memoryUsage.hpp"
35 #include "utilities/debug.hpp"
36 #include "utilities/events.hpp"
37 #include "utilities/formatBuffer.hpp"
38 #include "utilities/growableArray.hpp"
39
40 // A "CollectedHeap" is an implementation of a java heap for HotSpot. This
41 // is an abstract class: there may be many different kinds of heaps. This
42 // class defines the functions that a heap must implement, and contains
43 // infrastructure common to all heaps.
44
45 class AdaptiveSizePolicy;
46 class BarrierSet;
47 class CollectorPolicy;
48 class GCHeapSummary;
49 class GCTimer;
50 class GCTracer;
51 class GCMemoryManager;
52 class MemoryPool;
53 class MetaspaceSummary;
54 class SoftRefPolicy;
55 class Thread;
56 class ThreadClosure;
57 class VirtualSpaceSummary;
58 class WorkGang;
59 class nmethod;
60
61 class GCMessage : public FormatBuffer<1024> {
62 public:
63 bool is_before;
64
65 public:
66 GCMessage() {}
67 };
68
69 class CollectedHeap;
70
71 class GCHeapLog : public EventLogBase<GCMessage> {
72 private:
73 void log_heap(CollectedHeap* heap, bool before);
74
75 public:
76 GCHeapLog() : EventLogBase<GCMessage>("GC Heap History") {}
77
78 void log_heap_before(CollectedHeap* heap) {
79 log_heap(heap, true);
80 }
81 void log_heap_after(CollectedHeap* heap) {
82 log_heap(heap, false);
83 }
84 };
85
86 //
87 // CollectedHeap
88 // GenCollectedHeap
89 // SerialHeap
90 // CMSHeap
91 // G1CollectedHeap
92 // ShenandoahHeap
93 // ParallelScavengeHeap
94 // ZCollectedHeap
95 //
96 class CollectedHeap : public CHeapObj<mtInternal> {
97 friend class VMStructs;
98 friend class JVMCIVMStructs;
99 friend class IsGCActiveMark; // Block structured external access to _is_gc_active
100 friend class MemAllocator;
101
102 private:
103 #ifdef ASSERT
104 static int _fire_out_of_memory_count;
105 #endif
106
107 GCHeapLog* _gc_heap_log;
108
109 MemRegion _reserved;
110
111 protected:
112 bool _is_gc_active;
113
114 // Used for filler objects (static, but initialized in ctor).
115 static size_t _filler_array_max_size;
116
117 unsigned int _total_collections; // ... started
118 unsigned int _total_full_collections; // ... started
119 NOT_PRODUCT(volatile size_t _promotion_failure_alot_count;)
120 NOT_PRODUCT(volatile size_t _promotion_failure_alot_gc_number;)
121
122 // Reason for current garbage collection. Should be set to
123 // a value reflecting no collection between collections.
124 GCCause::Cause _gc_cause;
125 GCCause::Cause _gc_lastcause;
126 PerfStringVariable* _perf_gc_cause;
127 PerfStringVariable* _perf_gc_lastcause;
128
129 // Constructor
130 CollectedHeap();
131
132 // Create a new tlab. All TLAB allocations must go through this.
133 // To allow more flexible TLAB allocations min_size specifies
134 // the minimum size needed, while requested_size is the requested
135 // size based on ergonomics. The actually allocated size will be
136 // returned in actual_size.
137 virtual HeapWord* allocate_new_tlab(size_t min_size,
138 size_t requested_size,
139 size_t* actual_size);
140
141 // Reinitialize tlabs before resuming mutators.
142 virtual void resize_all_tlabs();
143
144 // Raw memory allocation facilities
145 // The obj and array allocate methods are covers for these methods.
146 // mem_allocate() should never be
147 // called to allocate TLABs, only individual objects.
148 virtual HeapWord* mem_allocate(size_t size,
149 bool* gc_overhead_limit_was_exceeded) = 0;
150
151 // Filler object utilities.
152 static inline size_t filler_array_hdr_size();
153 static inline size_t filler_array_min_size();
154
155 DEBUG_ONLY(static void fill_args_check(HeapWord* start, size_t words);)
156 DEBUG_ONLY(static void zap_filler_array(HeapWord* start, size_t words, bool zap = true);)
157
158 // Fill with a single array; caller must ensure filler_array_min_size() <=
159 // words <= filler_array_max_size().
160 static inline void fill_with_array(HeapWord* start, size_t words, bool zap = true);
161
162 // Fill with a single object (either an int array or a java.lang.Object).
163 static inline void fill_with_object_impl(HeapWord* start, size_t words, bool zap = true);
164
165 virtual void trace_heap(GCWhen::Type when, const GCTracer* tracer);
166
167 // Verification functions
168 virtual void check_for_non_bad_heap_word_value(HeapWord* addr, size_t size)
169 PRODUCT_RETURN;
170 debug_only(static void check_for_valid_allocation_state();)
171
172 public:
173 enum Name {
174 None,
175 Serial,
176 Parallel,
177 CMS,
178 G1,
179 Epsilon,
180 Z,
181 Shenandoah
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 virtual size_t min_dummy_object_size() const;
315 size_t tlab_alloc_reserve() const;
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 MemoryUsage memory_usage();
429 virtual GrowableArray<GCMemoryManager*> memory_managers() = 0;
430 virtual GrowableArray<MemoryPool*> memory_pools() = 0;
431
432 // Iterate over all objects, calling "cl.do_object" on each.
433 virtual void object_iterate(ObjectClosure* cl) = 0;
434
435 // Similar to object_iterate() except iterates only
436 // over live objects.
437 virtual void safe_object_iterate(ObjectClosure* cl) = 0;
438
439 // NOTE! There is no requirement that a collector implement these
440 // functions.
441 //
442 // A CollectedHeap is divided into a dense sequence of "blocks"; that is,
443 // each address in the (reserved) heap is a member of exactly
444 // one block. The defining characteristic of a block is that it is
445 // possible to find its size, and thus to progress forward to the next
446 // block. (Blocks may be of different sizes.) Thus, blocks may
447 // represent Java objects, or they might be free blocks in a
448 // free-list-based heap (or subheap), as long as the two kinds are
449 // distinguishable and the size of each is determinable.
450
451 // Returns the address of the start of the "block" that contains the
452 // address "addr". We say "blocks" instead of "object" since some heaps
453 // may not pack objects densely; a chunk may either be an object or a
454 // non-object.
455 virtual HeapWord* block_start(const void* addr) const = 0;
456
457 // Requires "addr" to be the start of a chunk, and returns its size.
458 // "addr + size" is required to be the start of a new chunk, or the end
459 // of the active area of the heap.
460 virtual size_t block_size(const HeapWord* addr) const = 0;
461
462 // Requires "addr" to be the start of a block, and returns "TRUE" iff
463 // the block is an object.
464 virtual bool block_is_obj(const HeapWord* addr) const = 0;
465
466 // Returns the longest time (in ms) that has elapsed since the last
467 // time that any part of the heap was examined by a garbage collection.
468 virtual jlong millis_since_last_gc() = 0;
469
470 // Perform any cleanup actions necessary before allowing a verification.
471 virtual void prepare_for_verify() = 0;
472
473 // Generate any dumps preceding or following a full gc
474 private:
475 void full_gc_dump(GCTimer* timer, bool before);
476
477 virtual void initialize_serviceability() = 0;
478
479 public:
480 void pre_full_gc_dump(GCTimer* timer);
481 void post_full_gc_dump(GCTimer* timer);
482
483 virtual VirtualSpaceSummary create_heap_space_summary();
484 GCHeapSummary create_heap_summary();
485
486 MetaspaceSummary create_metaspace_summary();
487
488 // Print heap information on the given outputStream.
489 virtual void print_on(outputStream* st) const = 0;
490 // The default behavior is to call print_on() on tty.
491 virtual void print() const {
492 print_on(tty);
493 }
494 // Print more detailed heap information on the given
495 // outputStream. The default behavior is to call print_on(). It is
496 // up to each subclass to override it and add any additional output
497 // it needs.
498 virtual void print_extended_on(outputStream* st) const {
499 print_on(st);
500 }
501
502 virtual void print_on_error(outputStream* st) const;
503
504 // Print all GC threads (other than the VM thread)
505 // used by this heap.
506 virtual void print_gc_threads_on(outputStream* st) const = 0;
507 // The default behavior is to call print_gc_threads_on() on tty.
508 void print_gc_threads() {
509 print_gc_threads_on(tty);
510 }
511 // Iterator for all GC threads (other than VM thread)
512 virtual void gc_threads_do(ThreadClosure* tc) const = 0;
513
514 // Print any relevant tracing info that flags imply.
515 // Default implementation does nothing.
516 virtual void print_tracing_info() const = 0;
517
518 void print_heap_before_gc();
519 void print_heap_after_gc();
520
521 // An object is scavengable if its location may move during a scavenge.
522 // (A scavenge is a GC which is not a full GC.)
523 virtual bool is_scavengable(oop obj) = 0;
524 // Registering and unregistering an nmethod (compiled code) with the heap.
525 // Override with specific mechanism for each specialized heap type.
526 virtual void register_nmethod(nmethod* nm) {}
527 virtual void unregister_nmethod(nmethod* nm) {}
528 virtual void verify_nmethod(nmethod* nmethod) {}
529
530 void trace_heap_before_gc(const GCTracer* gc_tracer);
531 void trace_heap_after_gc(const GCTracer* gc_tracer);
532
533 // Heap verification
534 virtual void verify(VerifyOption option) = 0;
535
536 // Return true if concurrent phase control (via
537 // request_concurrent_phase_control) is supported by this collector.
538 // The default implementation returns false.
539 virtual bool supports_concurrent_phase_control() const;
540
541 // Return a NULL terminated array of concurrent phase names provided
542 // by this collector. Supports Whitebox testing. These are the
543 // names recognized by request_concurrent_phase(). The default
544 // implementation returns an array of one NULL element.
545 virtual const char* const* concurrent_phases() const;
546
547 // Request the collector enter the indicated concurrent phase, and
548 // wait until it does so. Supports WhiteBox testing. Only one
549 // request may be active at a time. Phases are designated by name;
550 // the set of names and their meaning is GC-specific. Once the
551 // requested phase has been reached, the collector will attempt to
552 // avoid transitioning to a new phase until a new request is made.
553 // [Note: A collector might not be able to remain in a given phase.
554 // For example, a full collection might cancel an in-progress
555 // concurrent collection.]
556 //
557 // Returns true when the phase is reached. Returns false for an
558 // unknown phase. The default implementation returns false.
559 virtual bool request_concurrent_phase(const char* phase);
560
561 // Provides a thread pool to SafepointSynchronize to use
562 // for parallel safepoint cleanup.
563 // GCs that use a GC worker thread pool may want to share
564 // it for use during safepoint cleanup. This is only possible
565 // if the GC can pause and resume concurrent work (e.g. G1
566 // concurrent marking) for an intermittent non-GC safepoint.
567 // If this method returns NULL, SafepointSynchronize will
568 // perform cleanup tasks serially in the VMThread.
569 virtual WorkGang* get_safepoint_workers() { return NULL; }
570
571 // Support for object pinning. This is used by JNI Get*Critical()
572 // and Release*Critical() family of functions. If supported, the GC
573 // must guarantee that pinned objects never move.
574 virtual bool supports_object_pinning() const;
575 virtual oop pin_object(JavaThread* thread, oop obj);
576 virtual void unpin_object(JavaThread* thread, oop obj);
577
578 // Deduplicate the string, iff the GC supports string deduplication.
579 virtual void deduplicate_string(oop str);
580
581 virtual bool is_oop(oop object) const;
582
583 virtual size_t obj_size(oop obj) const;
584
585 // Cells are memory slices allocated by the allocator. Objects are initialized
586 // in cells. The cell itself may have a header, found at a negative offset of
587 // oops. Usually, the size of the cell header is 0, but it may be larger.
588 virtual ptrdiff_t cell_header_size() const { return 0; }
589
590 // Non product verification and debugging.
591 #ifndef PRODUCT
592 // Support for PromotionFailureALot. Return true if it's time to cause a
593 // promotion failure. The no-argument version uses
594 // this->_promotion_failure_alot_count as the counter.
595 bool promotion_should_fail(volatile size_t* count);
596 bool promotion_should_fail();
597
598 // Reset the PromotionFailureALot counters. Should be called at the end of a
599 // GC in which promotion failure occurred.
600 void reset_promotion_should_fail(volatile size_t* count);
601 void reset_promotion_should_fail();
602 #endif // #ifndef PRODUCT
603
604 #ifdef ASSERT
605 static int fired_fake_oom() {
606 return (CIFireOOMAt > 1 && _fire_out_of_memory_count >= CIFireOOMAt);
607 }
608 #endif
609 };
610
611 // Class to set and reset the GC cause for a CollectedHeap.
612
613 class GCCauseSetter : StackObj {
614 CollectedHeap* _heap;
615 GCCause::Cause _previous_cause;
616 public:
617 GCCauseSetter(CollectedHeap* heap, GCCause::Cause cause) {
618 _heap = heap;
619 _previous_cause = _heap->gc_cause();
620 _heap->set_gc_cause(cause);
621 }
622
623 ~GCCauseSetter() {
624 _heap->set_gc_cause(_previous_cause);
625 }
626 };
627
628 #endif // SHARE_VM_GC_SHARED_COLLECTEDHEAP_HPP