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 // ParallelScavengeHeap
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 // Reinitialize tlabs before resuming mutators.
141 virtual void resize_all_tlabs();
142
143 // Raw memory allocation facilities
144 // The obj and array allocate methods are covers for these methods.
145 // mem_allocate() should never be
146 // called to allocate TLABs, only individual objects.
147 virtual HeapWord* mem_allocate(size_t size,
148 bool* gc_overhead_limit_was_exceeded) = 0;
149
150 // Filler object utilities.
151 static inline size_t filler_array_hdr_size();
152 static inline size_t filler_array_min_size();
153
154 DEBUG_ONLY(static void fill_args_check(HeapWord* start, size_t words);)
155 DEBUG_ONLY(static void zap_filler_array(HeapWord* start, size_t words, bool zap = true);)
156
157 // Fill with a single array; caller must ensure filler_array_min_size() <=
158 // words <= filler_array_max_size().
159 static inline void fill_with_array(HeapWord* start, size_t words, bool zap = true);
160
161 // Fill with a single object (either an int array or a java.lang.Object).
162 static inline void fill_with_object_impl(HeapWord* start, size_t words, bool zap = true);
163
164 virtual void trace_heap(GCWhen::Type when, const GCTracer* tracer);
165
166 // Verification functions
167 virtual void check_for_non_bad_heap_word_value(HeapWord* addr, size_t size)
168 PRODUCT_RETURN;
169 debug_only(static void check_for_valid_allocation_state();)
170
171 public:
172 enum Name {
173 None,
174 Serial,
175 Parallel,
176 CMS,
177 G1,
178 Epsilon,
179 Z
180 };
181
182 static inline size_t filler_array_max_size() {
183 return _filler_array_max_size;
184 }
185
186 virtual Name kind() const = 0;
187
188 virtual const char* name() const = 0;
189
190 /**
191 * Returns JNI error code JNI_ENOMEM if memory could not be allocated,
192 * and JNI_OK on success.
193 */
194 virtual jint initialize() = 0;
195
196 // In many heaps, there will be a need to perform some initialization activities
197 // after the Universe is fully formed, but before general heap allocation is allowed.
198 // This is the correct place to place such initialization methods.
199 virtual void post_initialize();
200
201 // Stop any onging concurrent work and prepare for exit.
202 virtual void stop() {}
203
204 // Stop and resume concurrent GC threads interfering with safepoint operations
205 virtual void safepoint_synchronize_begin() {}
206 virtual void safepoint_synchronize_end() {}
207
208 void initialize_reserved_region(HeapWord *start, HeapWord *end);
209 MemRegion reserved_region() const { return _reserved; }
210 address base() const { return (address)reserved_region().start(); }
211
212 virtual size_t capacity() const = 0;
213 virtual size_t used() const = 0;
214
215 // Return "true" if the part of the heap that allocates Java
216 // objects has reached the maximal committed limit that it can
217 // reach, without a garbage collection.
218 virtual bool is_maximal_no_gc() const = 0;
219
220 // Support for java.lang.Runtime.maxMemory(): return the maximum amount of
221 // memory that the vm could make available for storing 'normal' java objects.
222 // This is based on the reserved address space, but should not include space
223 // that the vm uses internally for bookkeeping or temporary storage
224 // (e.g., in the case of the young gen, one of the survivor
225 // spaces).
226 virtual size_t max_capacity() const = 0;
227
228 // Returns "TRUE" if "p" points into the reserved area of the heap.
229 bool is_in_reserved(const void* p) const {
230 return _reserved.contains(p);
231 }
232
233 bool is_in_reserved_or_null(const void* p) const {
234 return p == NULL || is_in_reserved(p);
235 }
236
237 // Returns "TRUE" iff "p" points into the committed areas of the heap.
238 // This method can be expensive so avoid using it in performance critical
239 // code.
240 virtual bool is_in(const void* p) const = 0;
241
242 DEBUG_ONLY(bool is_in_or_null(const void* p) const { return p == NULL || is_in(p); })
243
244 // Let's define some terms: a "closed" subset of a heap is one that
245 //
246 // 1) contains all currently-allocated objects, and
247 //
248 // 2) is closed under reference: no object in the closed subset
249 // references one outside the closed subset.
250 //
251 // Membership in a heap's closed subset is useful for assertions.
252 // Clearly, the entire heap is a closed subset, so the default
253 // implementation is to use "is_in_reserved". But this may not be too
254 // liberal to perform useful checking. Also, the "is_in" predicate
255 // defines a closed subset, but may be too expensive, since "is_in"
256 // verifies that its argument points to an object head. The
257 // "closed_subset" method allows a heap to define an intermediate
258 // predicate, allowing more precise checking than "is_in_reserved" at
259 // lower cost than "is_in."
260
261 // One important case is a heap composed of disjoint contiguous spaces,
262 // such as the Garbage-First collector. Such heaps have a convenient
263 // closed subset consisting of the allocated portions of those
264 // contiguous spaces.
265
266 // Return "TRUE" iff the given pointer points into the heap's defined
267 // closed subset (which defaults to the entire heap).
268 virtual bool is_in_closed_subset(const void* p) const {
269 return is_in_reserved(p);
270 }
271
272 bool is_in_closed_subset_or_null(const void* p) const {
273 return p == NULL || is_in_closed_subset(p);
274 }
275
276 void set_gc_cause(GCCause::Cause v) {
277 if (UsePerfData) {
278 _gc_lastcause = _gc_cause;
279 _perf_gc_lastcause->set_value(GCCause::to_string(_gc_lastcause));
280 _perf_gc_cause->set_value(GCCause::to_string(v));
281 }
282 _gc_cause = v;
283 }
284 GCCause::Cause gc_cause() { return _gc_cause; }
285
286 virtual oop obj_allocate(Klass* klass, int size, TRAPS);
287 virtual oop array_allocate(Klass* klass, int size, int length, bool do_zero, TRAPS);
288 virtual oop class_allocate(Klass* klass, int size, TRAPS);
289
290 // Utilities for turning raw memory into filler objects.
291 //
292 // min_fill_size() is the smallest region that can be filled.
293 // fill_with_objects() can fill arbitrary-sized regions of the heap using
294 // multiple objects. fill_with_object() is for regions known to be smaller
295 // than the largest array of integers; it uses a single object to fill the
296 // region and has slightly less overhead.
297 static size_t min_fill_size() {
298 return size_t(align_object_size(oopDesc::header_size()));
299 }
300
301 static void fill_with_objects(HeapWord* start, size_t words, bool zap = true);
302
303 static void fill_with_object(HeapWord* start, size_t words, bool zap = true);
304 static void fill_with_object(MemRegion region, bool zap = true) {
305 fill_with_object(region.start(), region.word_size(), zap);
306 }
307 static void fill_with_object(HeapWord* start, HeapWord* end, bool zap = true) {
308 fill_with_object(start, pointer_delta(end, start), zap);
309 }
310
311 virtual void fill_with_dummy_object(HeapWord* start, HeapWord* end, bool zap);
312 virtual size_t min_dummy_object_size() const;
313 size_t tlab_alloc_reserve() const;
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 MemoryUsage memory_usage();
427 virtual GrowableArray<GCMemoryManager*> memory_managers() = 0;
428 virtual GrowableArray<MemoryPool*> memory_pools() = 0;
429
430 // Iterate over all objects, calling "cl.do_object" on each.
431 virtual void object_iterate(ObjectClosure* cl) = 0;
432
433 // Similar to object_iterate() except iterates only
434 // over live objects.
435 virtual void safe_object_iterate(ObjectClosure* cl) = 0;
436
437 // NOTE! There is no requirement that a collector implement these
438 // functions.
439 //
440 // A CollectedHeap is divided into a dense sequence of "blocks"; that is,
441 // each address in the (reserved) heap is a member of exactly
442 // one block. The defining characteristic of a block is that it is
443 // possible to find its size, and thus to progress forward to the next
444 // block. (Blocks may be of different sizes.) Thus, blocks may
445 // represent Java objects, or they might be free blocks in a
446 // free-list-based heap (or subheap), as long as the two kinds are
447 // distinguishable and the size of each is determinable.
448
449 // Returns the address of the start of the "block" that contains the
450 // address "addr". We say "blocks" instead of "object" since some heaps
451 // may not pack objects densely; a chunk may either be an object or a
452 // non-object.
453 virtual HeapWord* block_start(const void* addr) const = 0;
454
455 // Requires "addr" to be the start of a chunk, and returns its size.
456 // "addr + size" is required to be the start of a new chunk, or the end
457 // of the active area of the heap.
458 virtual size_t block_size(const HeapWord* addr) const = 0;
459
460 // Requires "addr" to be the start of a block, and returns "TRUE" iff
461 // the block is an object.
462 virtual bool block_is_obj(const HeapWord* addr) const = 0;
463
464 // Returns the longest time (in ms) that has elapsed since the last
465 // time that any part of the heap was examined by a garbage collection.
466 virtual jlong millis_since_last_gc() = 0;
467
468 // Perform any cleanup actions necessary before allowing a verification.
469 virtual void prepare_for_verify() = 0;
470
471 // Generate any dumps preceding or following a full gc
472 private:
473 void full_gc_dump(GCTimer* timer, bool before);
474
475 virtual void initialize_serviceability() = 0;
476
477 public:
478 void pre_full_gc_dump(GCTimer* timer);
479 void post_full_gc_dump(GCTimer* timer);
480
481 virtual VirtualSpaceSummary create_heap_space_summary();
482 GCHeapSummary create_heap_summary();
483
484 MetaspaceSummary create_metaspace_summary();
485
486 // Print heap information on the given outputStream.
487 virtual void print_on(outputStream* st) const = 0;
488 // The default behavior is to call print_on() on tty.
489 virtual void print() const {
490 print_on(tty);
491 }
492 // Print more detailed heap information on the given
493 // outputStream. The default behavior is to call print_on(). It is
494 // up to each subclass to override it and add any additional output
495 // it needs.
496 virtual void print_extended_on(outputStream* st) const {
497 print_on(st);
498 }
499
500 virtual void print_on_error(outputStream* st) const;
501
502 // Print all GC threads (other than the VM thread)
503 // used by this heap.
504 virtual void print_gc_threads_on(outputStream* st) const = 0;
505 // The default behavior is to call print_gc_threads_on() on tty.
506 void print_gc_threads() {
507 print_gc_threads_on(tty);
508 }
509 // Iterator for all GC threads (other than VM thread)
510 virtual void gc_threads_do(ThreadClosure* tc) const = 0;
511
512 // Print any relevant tracing info that flags imply.
513 // Default implementation does nothing.
514 virtual void print_tracing_info() const = 0;
515
516 void print_heap_before_gc();
517 void print_heap_after_gc();
518
519 // An object is scavengable if its location may move during a scavenge.
520 // (A scavenge is a GC which is not a full GC.)
521 virtual bool is_scavengable(oop obj) = 0;
522 // Registering and unregistering an nmethod (compiled code) with the heap.
523 // Override with specific mechanism for each specialized heap type.
524 virtual void register_nmethod(nmethod* nm) {}
525 virtual void unregister_nmethod(nmethod* nm) {}
526 virtual void verify_nmethod(nmethod* nmethod) {}
527
528 void trace_heap_before_gc(const GCTracer* gc_tracer);
529 void trace_heap_after_gc(const GCTracer* gc_tracer);
530
531 // Heap verification
532 virtual void verify(VerifyOption option) = 0;
533
534 // Return true if concurrent phase control (via
535 // request_concurrent_phase_control) is supported by this collector.
536 // The default implementation returns false.
537 virtual bool supports_concurrent_phase_control() const;
538
539 // Return a NULL terminated array of concurrent phase names provided
540 // by this collector. Supports Whitebox testing. These are the
541 // names recognized by request_concurrent_phase(). The default
542 // implementation returns an array of one NULL element.
543 virtual const char* const* concurrent_phases() const;
544
545 // Request the collector enter the indicated concurrent phase, and
546 // wait until it does so. Supports WhiteBox testing. Only one
547 // request may be active at a time. Phases are designated by name;
548 // the set of names and their meaning is GC-specific. Once the
549 // requested phase has been reached, the collector will attempt to
550 // avoid transitioning to a new phase until a new request is made.
551 // [Note: A collector might not be able to remain in a given phase.
552 // For example, a full collection might cancel an in-progress
553 // concurrent collection.]
554 //
555 // Returns true when the phase is reached. Returns false for an
556 // unknown phase. The default implementation returns false.
557 virtual bool request_concurrent_phase(const char* phase);
558
559 // Provides a thread pool to SafepointSynchronize to use
560 // for parallel safepoint cleanup.
561 // GCs that use a GC worker thread pool may want to share
562 // it for use during safepoint cleanup. This is only possible
563 // if the GC can pause and resume concurrent work (e.g. G1
564 // concurrent marking) for an intermittent non-GC safepoint.
565 // If this method returns NULL, SafepointSynchronize will
566 // perform cleanup tasks serially in the VMThread.
567 virtual WorkGang* get_safepoint_workers() { return NULL; }
568
569 // Support for object pinning. This is used by JNI Get*Critical()
570 // and Release*Critical() family of functions. If supported, the GC
571 // must guarantee that pinned objects never move.
572 virtual bool supports_object_pinning() const;
573 virtual oop pin_object(JavaThread* thread, oop obj);
574 virtual void unpin_object(JavaThread* thread, oop obj);
575
576 // Deduplicate the string, iff the GC supports string deduplication.
577 virtual void deduplicate_string(oop str);
578
579 virtual bool is_oop(oop object) const;
580
581 virtual size_t obj_size(oop obj) const;
582
583 // Non product verification and debugging.
584 #ifndef PRODUCT
585 // Support for PromotionFailureALot. Return true if it's time to cause a
586 // promotion failure. The no-argument version uses
587 // this->_promotion_failure_alot_count as the counter.
588 bool promotion_should_fail(volatile size_t* count);
589 bool promotion_should_fail();
590
591 // Reset the PromotionFailureALot counters. Should be called at the end of a
592 // GC in which promotion failure occurred.
593 void reset_promotion_should_fail(volatile size_t* count);
594 void reset_promotion_should_fail();
595 #endif // #ifndef PRODUCT
596
597 #ifdef ASSERT
598 static int fired_fake_oom() {
599 return (CIFireOOMAt > 1 && _fire_out_of_memory_count >= CIFireOOMAt);
600 }
601 #endif
602 };
603
604 // Class to set and reset the GC cause for a CollectedHeap.
605
606 class GCCauseSetter : StackObj {
607 CollectedHeap* _heap;
608 GCCause::Cause _previous_cause;
609 public:
610 GCCauseSetter(CollectedHeap* heap, GCCause::Cause cause) {
611 _heap = heap;
612 _previous_cause = _heap->gc_cause();
613 _heap->set_gc_cause(cause);
614 }
615
616 ~GCCauseSetter() {
617 _heap->set_gc_cause(_previous_cause);
618 }
619 };
620
621 #endif // SHARE_VM_GC_SHARED_COLLECTEDHEAP_HPP