1 /*
2 * Copyright (c) 2001, 2019, 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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19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
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23 */
24
25 #ifndef SHARE_GC_SHARED_COLLECTEDHEAP_HPP
26 #define SHARE_GC_SHARED_COLLECTEDHEAP_HPP
27
28 #include "gc/shared/gcCause.hpp"
29 #include "gc/shared/gcWhen.hpp"
30 #include "gc/shared/verifyOption.hpp"
31 #include "memory/allocation.hpp"
32 #include "memory/metaspace/metaspaceEnums.hpp"
33 #include "runtime/handles.hpp"
34 #include "runtime/perfData.hpp"
35 #include "runtime/safepoint.hpp"
36 #include "services/memoryUsage.hpp"
37 #include "utilities/debug.hpp"
38 #include "utilities/events.hpp"
39 #include "utilities/formatBuffer.hpp"
40 #include "utilities/growableArray.hpp"
41
42 // A "CollectedHeap" is an implementation of a java heap for HotSpot. This
43 // is an abstract class: there may be many different kinds of heaps. This
44 // class defines the functions that a heap must implement, and contains
45 // infrastructure common to all heaps.
46
47 class AdaptiveSizePolicy;
48 class BarrierSet;
49 class GCHeapSummary;
50 class GCTimer;
51 class GCTracer;
52 class GCMemoryManager;
53 class MemoryPool;
54 class MetaspaceSummary;
55 class SoftRefPolicy;
56 class Thread;
57 class ThreadClosure;
58 class VirtualSpaceSummary;
59 class WorkGang;
60 class nmethod;
61
62 class GCMessage : public FormatBuffer<1024> {
63 public:
64 bool is_before;
65
66 public:
67 GCMessage() {}
68 };
69
70 class CollectedHeap;
71
72 class GCHeapLog : public EventLogBase<GCMessage> {
73 private:
74 void log_heap(CollectedHeap* heap, bool before);
75
76 public:
77 GCHeapLog() : EventLogBase<GCMessage>("GC Heap History", "gc") {}
78
79 void log_heap_before(CollectedHeap* heap) {
80 log_heap(heap, true);
81 }
82 void log_heap_after(CollectedHeap* heap) {
83 log_heap(heap, false);
84 }
85 };
86
87 //
88 // CollectedHeap
89 // GenCollectedHeap
90 // SerialHeap
91 // CMSHeap
92 // G1CollectedHeap
93 // ParallelScavengeHeap
94 // ShenandoahHeap
95 // ZCollectedHeap
96 //
97 class CollectedHeap : public CHeapObj<mtInternal> {
98 friend class VMStructs;
99 friend class JVMCIVMStructs;
100 friend class IsGCActiveMark; // Block structured external access to _is_gc_active
101 friend class MemAllocator;
102
103 private:
104 GCHeapLog* _gc_heap_log;
105
106 MemRegion _reserved;
107
108 protected:
109 bool _is_gc_active;
110
111 // Used for filler objects (static, but initialized in ctor).
112 static size_t _filler_array_max_size;
113
114 unsigned int _total_collections; // ... started
115 unsigned int _total_full_collections; // ... started
116 NOT_PRODUCT(volatile size_t _promotion_failure_alot_count;)
117 NOT_PRODUCT(volatile size_t _promotion_failure_alot_gc_number;)
118
119 // Reason for current garbage collection. Should be set to
120 // a value reflecting no collection between collections.
121 GCCause::Cause _gc_cause;
122 GCCause::Cause _gc_lastcause;
123 PerfStringVariable* _perf_gc_cause;
124 PerfStringVariable* _perf_gc_lastcause;
125
126 // Constructor
127 CollectedHeap();
128
129 // Create a new tlab. All TLAB allocations must go through this.
130 // To allow more flexible TLAB allocations min_size specifies
131 // the minimum size needed, while requested_size is the requested
132 // size based on ergonomics. The actually allocated size will be
133 // returned in actual_size.
134 virtual HeapWord* allocate_new_tlab(size_t min_size,
135 size_t requested_size,
136 size_t* actual_size);
137
138 // Reinitialize tlabs before resuming mutators.
139 virtual void resize_all_tlabs();
140
141 // Raw memory allocation facilities
142 // The obj and array allocate methods are covers for these methods.
143 // mem_allocate() should never be
144 // called to allocate TLABs, only individual objects.
145 virtual HeapWord* mem_allocate(size_t size,
146 bool* gc_overhead_limit_was_exceeded) = 0;
147
148 // Filler object utilities.
149 static inline size_t filler_array_hdr_size();
150 static inline size_t filler_array_min_size();
151
152 DEBUG_ONLY(static void fill_args_check(HeapWord* start, size_t words);)
153 DEBUG_ONLY(static void zap_filler_array(HeapWord* start, size_t words, bool zap = true);)
154
155 // Fill with a single array; caller must ensure filler_array_min_size() <=
156 // words <= filler_array_max_size().
157 static inline void fill_with_array(HeapWord* start, size_t words, bool zap = true);
158
159 // Fill with a single object (either an int array or a java.lang.Object).
160 static inline void fill_with_object_impl(HeapWord* start, size_t words, bool zap = true);
161
162 virtual void trace_heap(GCWhen::Type when, const GCTracer* tracer);
163
164 // Verification functions
165 virtual void check_for_non_bad_heap_word_value(HeapWord* addr, size_t size)
166 PRODUCT_RETURN;
167 debug_only(static void check_for_valid_allocation_state();)
168
169 public:
170 enum Name {
171 None,
172 Serial,
173 Parallel,
174 CMS,
175 G1,
176 Epsilon,
177 Z,
178 Shenandoah
179 };
180
181 static inline size_t filler_array_max_size() {
182 return _filler_array_max_size;
183 }
184
185 virtual Name kind() const = 0;
186
187 virtual const char* name() const = 0;
188
189 /**
190 * Returns JNI error code JNI_ENOMEM if memory could not be allocated,
191 * and JNI_OK on success.
192 */
193 virtual jint initialize() = 0;
194
195 // In many heaps, there will be a need to perform some initialization activities
196 // after the Universe is fully formed, but before general heap allocation is allowed.
197 // This is the correct place to place such initialization methods.
198 virtual void post_initialize();
199
200 // Stop any onging concurrent work and prepare for exit.
201 virtual void stop() {}
202
203 // Stop and resume concurrent GC threads interfering with safepoint operations
204 virtual void safepoint_synchronize_begin() {}
205 virtual void safepoint_synchronize_end() {}
206
207 void initialize_reserved_region(HeapWord *start, HeapWord *end);
208 MemRegion reserved_region() const { return _reserved; }
209 address base() const { return (address)reserved_region().start(); }
210
211 virtual size_t capacity() const = 0;
212 virtual size_t used() const = 0;
213
214 // Returns unused capacity.
215 virtual size_t unused() const;
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 virtual uint32_t hash_oop(oop obj) const;
247
248 void set_gc_cause(GCCause::Cause v) {
249 if (UsePerfData) {
250 _gc_lastcause = _gc_cause;
251 _perf_gc_lastcause->set_value(GCCause::to_string(_gc_lastcause));
252 _perf_gc_cause->set_value(GCCause::to_string(v));
253 }
254 _gc_cause = v;
255 }
256 GCCause::Cause gc_cause() { return _gc_cause; }
257
258 virtual oop obj_allocate(Klass* klass, int size, TRAPS);
259 virtual oop array_allocate(Klass* klass, int size, int length, bool do_zero, TRAPS);
260 virtual oop class_allocate(Klass* klass, int size, TRAPS);
261
262 // Utilities for turning raw memory into filler objects.
263 //
264 // min_fill_size() is the smallest region that can be filled.
265 // fill_with_objects() can fill arbitrary-sized regions of the heap using
266 // multiple objects. fill_with_object() is for regions known to be smaller
267 // than the largest array of integers; it uses a single object to fill the
268 // region and has slightly less overhead.
269 static size_t min_fill_size() {
270 return size_t(align_object_size(oopDesc::header_size()));
271 }
272
273 static void fill_with_objects(HeapWord* start, size_t words, bool zap = true);
274
275 static void fill_with_object(HeapWord* start, size_t words, bool zap = true);
276 static void fill_with_object(MemRegion region, bool zap = true) {
277 fill_with_object(region.start(), region.word_size(), zap);
278 }
279 static void fill_with_object(HeapWord* start, HeapWord* end, bool zap = true) {
280 fill_with_object(start, pointer_delta(end, start), zap);
281 }
282
283 virtual void fill_with_dummy_object(HeapWord* start, HeapWord* end, bool zap);
284 virtual size_t min_dummy_object_size() const;
285 size_t tlab_alloc_reserve() const;
286
287 // Return the address "addr" aligned by "alignment_in_bytes" if such
288 // an address is below "end". Return NULL otherwise.
289 inline static HeapWord* align_allocation_or_fail(HeapWord* addr,
290 HeapWord* end,
291 unsigned short alignment_in_bytes);
292
293 // Some heaps may offer a contiguous region for shared non-blocking
294 // allocation, via inlined code (by exporting the address of the top and
295 // end fields defining the extent of the contiguous allocation region.)
296
297 // This function returns "true" iff the heap supports this kind of
298 // allocation. (Default is "no".)
299 virtual bool supports_inline_contig_alloc() const {
300 return false;
301 }
302 // These functions return the addresses of the fields that define the
303 // boundaries of the contiguous allocation area. (These fields should be
304 // physically near to one another.)
305 virtual HeapWord* volatile* top_addr() const {
306 guarantee(false, "inline contiguous allocation not supported");
307 return NULL;
308 }
309 virtual HeapWord** end_addr() const {
310 guarantee(false, "inline contiguous allocation not supported");
311 return NULL;
312 }
313
314 // Some heaps may be in an unparseable state at certain times between
315 // collections. This may be necessary for efficient implementation of
316 // certain allocation-related activities. Calling this function before
317 // attempting to parse a heap ensures that the heap is in a parsable
318 // state (provided other concurrent activity does not introduce
319 // unparsability). It is normally expected, therefore, that this
320 // method is invoked with the world stopped.
321 // NOTE: if you override this method, make sure you call
322 // super::ensure_parsability so that the non-generational
323 // part of the work gets done. See implementation of
324 // CollectedHeap::ensure_parsability and, for instance,
325 // that of GenCollectedHeap::ensure_parsability().
326 // The argument "retire_tlabs" controls whether existing TLABs
327 // are merely filled or also retired, thus preventing further
328 // allocation from them and necessitating allocation of new TLABs.
329 virtual void ensure_parsability(bool retire_tlabs);
330
331 // Section on thread-local allocation buffers (TLABs)
332 // If the heap supports thread-local allocation buffers, it should override
333 // the following methods:
334 // Returns "true" iff the heap supports thread-local allocation buffers.
335 // The default is "no".
336 virtual bool supports_tlab_allocation() const = 0;
337
338 // The amount of space available for thread-local allocation buffers.
339 virtual size_t tlab_capacity(Thread *thr) const = 0;
340
341 // The amount of used space for thread-local allocation buffers for the given thread.
342 virtual size_t tlab_used(Thread *thr) const = 0;
343
344 virtual size_t max_tlab_size() const;
345
346 // An estimate of the maximum allocation that could be performed
347 // for thread-local allocation buffers without triggering any
348 // collection or expansion activity.
349 virtual size_t unsafe_max_tlab_alloc(Thread *thr) const {
350 guarantee(false, "thread-local allocation buffers not supported");
351 return 0;
352 }
353
354 // Perform a collection of the heap; intended for use in implementing
355 // "System.gc". This probably implies as full a collection as the
356 // "CollectedHeap" supports.
357 virtual void collect(GCCause::Cause cause) = 0;
358
359 // Perform a full collection
360 virtual void do_full_collection(bool clear_all_soft_refs) = 0;
361
362 // This interface assumes that it's being called by the
363 // vm thread. It collects the heap assuming that the
364 // heap lock is already held and that we are executing in
365 // the context of the vm thread.
366 virtual void collect_as_vm_thread(GCCause::Cause cause);
367
368 virtual MetaWord* satisfy_failed_metadata_allocation(ClassLoaderData* loader_data,
369 size_t size,
370 metaspace::MetadataType mdtype);
371
372 // Returns "true" iff there is a stop-world GC in progress. (I assume
373 // that it should answer "false" for the concurrent part of a concurrent
374 // collector -- dld).
375 bool is_gc_active() const { return _is_gc_active; }
376
377 // Total number of GC collections (started)
378 unsigned int total_collections() const { return _total_collections; }
379 unsigned int total_full_collections() const { return _total_full_collections;}
380
381 // Increment total number of GC collections (started)
382 // Should be protected but used by PSMarkSweep - cleanup for 1.4.2
383 void increment_total_collections(bool full = false) {
384 _total_collections++;
385 if (full) {
386 increment_total_full_collections();
387 }
388 }
389
390 void increment_total_full_collections() { _total_full_collections++; }
391
392 // Return the SoftRefPolicy for the heap;
393 virtual SoftRefPolicy* soft_ref_policy() = 0;
394
395 virtual MemoryUsage memory_usage();
396 virtual GrowableArray<GCMemoryManager*> memory_managers() = 0;
397 virtual GrowableArray<MemoryPool*> memory_pools() = 0;
398
399 // Iterate over all objects, calling "cl.do_object" on each.
400 virtual void object_iterate(ObjectClosure* cl) = 0;
401
402 // Similar to object_iterate() except iterates only
403 // over live objects.
404 virtual void safe_object_iterate(ObjectClosure* cl) = 0;
405
406 // NOTE! There is no requirement that a collector implement these
407 // functions.
408 //
409 // A CollectedHeap is divided into a dense sequence of "blocks"; that is,
410 // each address in the (reserved) heap is a member of exactly
411 // one block. The defining characteristic of a block is that it is
412 // possible to find its size, and thus to progress forward to the next
413 // block. (Blocks may be of different sizes.) Thus, blocks may
414 // represent Java objects, or they might be free blocks in a
415 // free-list-based heap (or subheap), as long as the two kinds are
416 // distinguishable and the size of each is determinable.
417
418 // Returns the address of the start of the "block" that contains the
419 // address "addr". We say "blocks" instead of "object" since some heaps
420 // may not pack objects densely; a chunk may either be an object or a
421 // non-object.
422 virtual HeapWord* block_start(const void* addr) const = 0;
423
424 // Requires "addr" to be the start of a block, and returns "TRUE" iff
425 // the block is an object.
426 virtual bool block_is_obj(const HeapWord* addr) const = 0;
427
428 // Returns the longest time (in ms) that has elapsed since the last
429 // time that any part of the heap was examined by a garbage collection.
430 virtual jlong millis_since_last_gc() = 0;
431
432 // Perform any cleanup actions necessary before allowing a verification.
433 virtual void prepare_for_verify() = 0;
434
435 // Generate any dumps preceding or following a full gc
436 private:
437 void full_gc_dump(GCTimer* timer, bool before);
438
439 virtual void initialize_serviceability() = 0;
440
441 public:
442 void pre_full_gc_dump(GCTimer* timer);
443 void post_full_gc_dump(GCTimer* timer);
444
445 virtual VirtualSpaceSummary create_heap_space_summary();
446 GCHeapSummary create_heap_summary();
447
448 MetaspaceSummary create_metaspace_summary();
449
450 // Print heap information on the given outputStream.
451 virtual void print_on(outputStream* st) const = 0;
452 // The default behavior is to call print_on() on tty.
453 virtual void print() const;
454
455 // Print more detailed heap information on the given
456 // outputStream. The default behavior is to call print_on(). It is
457 // up to each subclass to override it and add any additional output
458 // it needs.
459 virtual void print_extended_on(outputStream* st) const {
460 print_on(st);
461 }
462
463 virtual void print_on_error(outputStream* st) const;
464
465 // Print all GC threads (other than the VM thread)
466 // used by this heap.
467 virtual void print_gc_threads_on(outputStream* st) const = 0;
468 // The default behavior is to call print_gc_threads_on() on tty.
469 void print_gc_threads() {
470 print_gc_threads_on(tty);
471 }
472 // Iterator for all GC threads (other than VM thread)
473 virtual void gc_threads_do(ThreadClosure* tc) const = 0;
474
475 // Print any relevant tracing info that flags imply.
476 // Default implementation does nothing.
477 virtual void print_tracing_info() const = 0;
478
479 void print_heap_before_gc();
480 void print_heap_after_gc();
481
482 // Registering and unregistering an nmethod (compiled code) with the heap.
483 virtual void register_nmethod(nmethod* nm) = 0;
484 virtual void unregister_nmethod(nmethod* nm) = 0;
485 // Callback for when nmethod is about to be deleted.
486 virtual void flush_nmethod(nmethod* nm) = 0;
487 virtual void verify_nmethod(nmethod* nm) = 0;
488
489 void trace_heap_before_gc(const GCTracer* gc_tracer);
490 void trace_heap_after_gc(const GCTracer* gc_tracer);
491
492 // Heap verification
493 virtual void verify(VerifyOption option) = 0;
494
495 // Return true if concurrent phase control (via
496 // request_concurrent_phase_control) is supported by this collector.
497 // The default implementation returns false.
498 virtual bool supports_concurrent_phase_control() const;
499
500 // Request the collector enter the indicated concurrent phase, and
501 // wait until it does so. Supports WhiteBox testing. Only one
502 // request may be active at a time. Phases are designated by name;
503 // the set of names and their meaning is GC-specific. Once the
504 // requested phase has been reached, the collector will attempt to
505 // avoid transitioning to a new phase until a new request is made.
506 // [Note: A collector might not be able to remain in a given phase.
507 // For example, a full collection might cancel an in-progress
508 // concurrent collection.]
509 //
510 // Returns true when the phase is reached. Returns false for an
511 // unknown phase. The default implementation returns false.
512 virtual bool request_concurrent_phase(const char* phase);
513
514 // Provides a thread pool to SafepointSynchronize to use
515 // for parallel safepoint cleanup.
516 // GCs that use a GC worker thread pool may want to share
517 // it for use during safepoint cleanup. This is only possible
518 // if the GC can pause and resume concurrent work (e.g. G1
519 // concurrent marking) for an intermittent non-GC safepoint.
520 // If this method returns NULL, SafepointSynchronize will
521 // perform cleanup tasks serially in the VMThread.
522 virtual WorkGang* get_safepoint_workers() { return NULL; }
523
524 // Support for object pinning. This is used by JNI Get*Critical()
525 // and Release*Critical() family of functions. If supported, the GC
526 // must guarantee that pinned objects never move.
527 virtual bool supports_object_pinning() const;
528 virtual oop pin_object(JavaThread* thread, oop obj);
529 virtual void unpin_object(JavaThread* thread, oop obj);
530
531 // Deduplicate the string, iff the GC supports string deduplication.
532 virtual void deduplicate_string(oop str);
533
534 virtual bool is_oop(oop object) const;
535
536 virtual size_t obj_size(oop obj) const;
537
538 // Non product verification and debugging.
539 #ifndef PRODUCT
540 // Support for PromotionFailureALot. Return true if it's time to cause a
541 // promotion failure. The no-argument version uses
542 // this->_promotion_failure_alot_count as the counter.
543 bool promotion_should_fail(volatile size_t* count);
544 bool promotion_should_fail();
545
546 // Reset the PromotionFailureALot counters. Should be called at the end of a
547 // GC in which promotion failure occurred.
548 void reset_promotion_should_fail(volatile size_t* count);
549 void reset_promotion_should_fail();
550 #endif // #ifndef PRODUCT
551 };
552
553 // Class to set and reset the GC cause for a CollectedHeap.
554
555 class GCCauseSetter : StackObj {
556 CollectedHeap* _heap;
557 GCCause::Cause _previous_cause;
558 public:
559 GCCauseSetter(CollectedHeap* heap, GCCause::Cause cause) {
560 _heap = heap;
561 _previous_cause = _heap->gc_cause();
562 _heap->set_gc_cause(cause);
563 }
564
565 ~GCCauseSetter() {
566 _heap->set_gc_cause(_previous_cause);
567 }
568 };
569
570 #endif // SHARE_GC_SHARED_COLLECTEDHEAP_HPP