1 /*
2 * Copyright (c) 2001, 2020, 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.
18 *
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
21 * questions.
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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/universe.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 ReservedHeapSpace;
56 class SoftRefPolicy;
57 class Thread;
58 class ThreadClosure;
59 class VirtualSpaceSummary;
60 class WorkGang;
61 class nmethod;
62
63 class GCMessage : public FormatBuffer<1024> {
64 public:
65 bool is_before;
66
67 public:
68 GCMessage() {}
69 };
70
71 class CollectedHeap;
72
73 class GCHeapLog : public EventLogBase<GCMessage> {
74 private:
75 void log_heap(CollectedHeap* heap, bool before);
76
77 public:
78 GCHeapLog() : EventLogBase<GCMessage>("GC Heap History", "gc") {}
79
80 void log_heap_before(CollectedHeap* heap) {
81 log_heap(heap, true);
82 }
83 void log_heap_after(CollectedHeap* heap) {
84 log_heap(heap, false);
85 }
86 };
87
88 //
89 // CollectedHeap
90 // GenCollectedHeap
91 // SerialHeap
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 protected:
107 // Not used by all GCs
108 MemRegion _reserved;
109
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 // Last time the whole heap has been examined in support of RMI
116 // MaxObjectInspectionAge.
117 // This timestamp must be monotonically non-decreasing to avoid
118 // time-warp warnings.
119 jlong _last_whole_heap_examined_time_ns;
120
121 unsigned int _total_collections; // ... started
122 unsigned int _total_full_collections; // ... started
123 NOT_PRODUCT(volatile size_t _promotion_failure_alot_count;)
124 NOT_PRODUCT(volatile size_t _promotion_failure_alot_gc_number;)
125
126 // Reason for current garbage collection. Should be set to
127 // a value reflecting no collection between collections.
128 GCCause::Cause _gc_cause;
129 GCCause::Cause _gc_lastcause;
130 PerfStringVariable* _perf_gc_cause;
131 PerfStringVariable* _perf_gc_lastcause;
132
133 // Constructor
134 CollectedHeap();
135
136 // Create a new tlab. All TLAB allocations must go through this.
137 // To allow more flexible TLAB allocations min_size specifies
138 // the minimum size needed, while requested_size is the requested
139 // size based on ergonomics. The actually allocated size will be
140 // returned in actual_size.
141 virtual HeapWord* allocate_new_tlab(size_t min_size,
142 size_t requested_size,
143 size_t* actual_size);
144
145 // Reinitialize tlabs before resuming mutators.
146 virtual void resize_all_tlabs();
147
148 // Raw memory allocation facilities
149 // The obj and array allocate methods are covers for these methods.
150 // mem_allocate() should never be
151 // called to allocate TLABs, only individual objects.
152 virtual HeapWord* mem_allocate(size_t size,
153 bool* gc_overhead_limit_was_exceeded) = 0;
154
155 // Filler object utilities.
156 static inline size_t filler_array_hdr_size();
157 static inline size_t filler_array_min_size();
158
159 DEBUG_ONLY(static void fill_args_check(HeapWord* start, size_t words);)
160 DEBUG_ONLY(static void zap_filler_array(HeapWord* start, size_t words, bool zap = true);)
161
162 // Fill with a single array; caller must ensure filler_array_min_size() <=
163 // words <= filler_array_max_size().
164 static inline void fill_with_array(HeapWord* start, size_t words, bool zap = true);
165
166 // Fill with a single object (either an int array or a java.lang.Object).
167 static inline void fill_with_object_impl(HeapWord* start, size_t words, bool zap = true);
168
169 virtual void trace_heap(GCWhen::Type when, const GCTracer* tracer);
170
171 // Verification functions
172 virtual void check_for_non_bad_heap_word_value(HeapWord* addr, size_t size)
173 PRODUCT_RETURN;
174 debug_only(static void check_for_valid_allocation_state();)
175
176 public:
177 enum Name {
178 None,
179 Serial,
180 Parallel,
181 G1,
182 Epsilon,
183 Z,
184 Shenandoah
185 };
186
187 protected:
188 // Get a pointer to the derived heap object. Used to implement
189 // derived class heap() functions rather than being called directly.
190 template<typename T>
191 static T* named_heap(Name kind) {
192 CollectedHeap* heap = Universe::heap();
193 assert(heap != NULL, "Uninitialized heap");
194 assert(kind == heap->kind(), "Heap kind %u should be %u",
195 static_cast<uint>(heap->kind()), static_cast<uint>(kind));
196 return static_cast<T*>(heap);
197 }
198
199 public:
200
201 static inline size_t filler_array_max_size() {
202 return _filler_array_max_size;
203 }
204
205 virtual Name kind() const = 0;
206
207 virtual const char* name() const = 0;
208
209 /**
210 * Returns JNI error code JNI_ENOMEM if memory could not be allocated,
211 * and JNI_OK on success.
212 */
213 virtual jint initialize() = 0;
214
215 // In many heaps, there will be a need to perform some initialization activities
216 // after the Universe is fully formed, but before general heap allocation is allowed.
217 // This is the correct place to place such initialization methods.
218 virtual void post_initialize();
219
220 // Stop any onging concurrent work and prepare for exit.
221 virtual void stop() {}
222
223 // Stop and resume concurrent GC threads interfering with safepoint operations
224 virtual void safepoint_synchronize_begin() {}
225 virtual void safepoint_synchronize_end() {}
226
227 void initialize_reserved_region(const ReservedHeapSpace& rs);
228
229 virtual size_t capacity() const = 0;
230 virtual size_t used() const = 0;
231
232 // Returns unused capacity.
233 virtual size_t unused() const;
234
235 // Return "true" if the part of the heap that allocates Java
236 // objects has reached the maximal committed limit that it can
237 // reach, without a garbage collection.
238 virtual bool is_maximal_no_gc() const = 0;
239
240 // Support for java.lang.Runtime.maxMemory(): return the maximum amount of
241 // memory that the vm could make available for storing 'normal' java objects.
242 // This is based on the reserved address space, but should not include space
243 // that the vm uses internally for bookkeeping or temporary storage
244 // (e.g., in the case of the young gen, one of the survivor
245 // spaces).
246 virtual size_t max_capacity() const = 0;
247
248 // Returns "TRUE" iff "p" points into the committed areas of the heap.
249 // This method can be expensive so avoid using it in performance critical
250 // code.
251 virtual bool is_in(const void* p) const = 0;
252
253 DEBUG_ONLY(bool is_in_or_null(const void* p) const { return p == NULL || is_in(p); })
254
255 virtual uint32_t hash_oop(oop obj) const;
256
257 void set_gc_cause(GCCause::Cause v) {
258 if (UsePerfData) {
259 _gc_lastcause = _gc_cause;
260 _perf_gc_lastcause->set_value(GCCause::to_string(_gc_lastcause));
261 _perf_gc_cause->set_value(GCCause::to_string(v));
262 }
263 _gc_cause = v;
264 }
265 GCCause::Cause gc_cause() { return _gc_cause; }
266
267 oop obj_allocate(Klass* klass, int size, TRAPS);
268 virtual oop array_allocate(Klass* klass, int size, int length, bool do_zero, TRAPS);
269 oop class_allocate(Klass* klass, int size, TRAPS);
270
271 // Utilities for turning raw memory into filler objects.
272 //
273 // min_fill_size() is the smallest region that can be filled.
274 // fill_with_objects() can fill arbitrary-sized regions of the heap using
275 // multiple objects. fill_with_object() is for regions known to be smaller
276 // than the largest array of integers; it uses a single object to fill the
277 // region and has slightly less overhead.
278 static size_t min_fill_size() {
279 return size_t(align_object_size(oopDesc::header_size()));
280 }
281
282 static void fill_with_objects(HeapWord* start, size_t words, bool zap = true);
283
284 static void fill_with_object(HeapWord* start, size_t words, bool zap = true);
285 static void fill_with_object(MemRegion region, bool zap = true) {
286 fill_with_object(region.start(), region.word_size(), zap);
287 }
288 static void fill_with_object(HeapWord* start, HeapWord* end, bool zap = true) {
289 fill_with_object(start, pointer_delta(end, start), zap);
290 }
291
292 virtual void fill_with_dummy_object(HeapWord* start, HeapWord* end, bool zap);
293 virtual size_t min_dummy_object_size() const;
294 size_t tlab_alloc_reserve() const;
295
296 // Return the address "addr" aligned by "alignment_in_bytes" if such
297 // an address is below "end". Return NULL otherwise.
298 inline static HeapWord* align_allocation_or_fail(HeapWord* addr,
299 HeapWord* end,
300 unsigned short alignment_in_bytes);
301
302 // Some heaps may offer a contiguous region for shared non-blocking
303 // allocation, via inlined code (by exporting the address of the top and
304 // end fields defining the extent of the contiguous allocation region.)
305
306 // This function returns "true" iff the heap supports this kind of
307 // allocation. (Default is "no".)
308 virtual bool supports_inline_contig_alloc() const {
309 return false;
310 }
311 // These functions return the addresses of the fields that define the
312 // boundaries of the contiguous allocation area. (These fields should be
313 // physically near to one another.)
314 virtual HeapWord* volatile* top_addr() const {
315 guarantee(false, "inline contiguous allocation not supported");
316 return NULL;
317 }
318 virtual HeapWord** end_addr() const {
319 guarantee(false, "inline contiguous allocation not supported");
320 return NULL;
321 }
322
323 // Some heaps may be in an unparseable state at certain times between
324 // collections. This may be necessary for efficient implementation of
325 // certain allocation-related activities. Calling this function before
326 // attempting to parse a heap ensures that the heap is in a parsable
327 // state (provided other concurrent activity does not introduce
328 // unparsability). It is normally expected, therefore, that this
329 // method is invoked with the world stopped.
330 // NOTE: if you override this method, make sure you call
331 // super::ensure_parsability so that the non-generational
332 // part of the work gets done. See implementation of
333 // CollectedHeap::ensure_parsability and, for instance,
334 // that of GenCollectedHeap::ensure_parsability().
335 // The argument "retire_tlabs" controls whether existing TLABs
336 // are merely filled or also retired, thus preventing further
337 // allocation from them and necessitating allocation of new TLABs.
338 virtual void ensure_parsability(bool retire_tlabs);
339
340 // Section on thread-local allocation buffers (TLABs)
341 // If the heap supports thread-local allocation buffers, it should override
342 // the following methods:
343 // Returns "true" iff the heap supports thread-local allocation buffers.
344 // The default is "no".
345 virtual bool supports_tlab_allocation() const = 0;
346
347 // The amount of space available for thread-local allocation buffers.
348 virtual size_t tlab_capacity(Thread *thr) const = 0;
349
350 // The amount of used space for thread-local allocation buffers for the given thread.
351 virtual size_t tlab_used(Thread *thr) const = 0;
352
353 virtual size_t max_tlab_size() const;
354
355 // An estimate of the maximum allocation that could be performed
356 // for thread-local allocation buffers without triggering any
357 // collection or expansion activity.
358 virtual size_t unsafe_max_tlab_alloc(Thread *thr) const {
359 guarantee(false, "thread-local allocation buffers not supported");
360 return 0;
361 }
362
363 // Perform a collection of the heap; intended for use in implementing
364 // "System.gc". This probably implies as full a collection as the
365 // "CollectedHeap" supports.
366 virtual void collect(GCCause::Cause cause) = 0;
367
368 // Perform a full collection
369 virtual void do_full_collection(bool clear_all_soft_refs) = 0;
370
371 // This interface assumes that it's being called by the
372 // vm thread. It collects the heap assuming that the
373 // heap lock is already held and that we are executing in
374 // the context of the vm thread.
375 virtual void collect_as_vm_thread(GCCause::Cause cause);
376
377 virtual MetaWord* satisfy_failed_metadata_allocation(ClassLoaderData* loader_data,
378 size_t size,
379 Metaspace::MetadataType mdtype);
380
381 // Returns "true" iff there is a stop-world GC in progress. (I assume
382 // that it should answer "false" for the concurrent part of a concurrent
383 // collector -- dld).
384 bool is_gc_active() const { return _is_gc_active; }
385
386 // Total number of GC collections (started)
387 unsigned int total_collections() const { return _total_collections; }
388 unsigned int total_full_collections() const { return _total_full_collections;}
389
390 // Increment total number of GC collections (started)
391 void increment_total_collections(bool full = false) {
392 _total_collections++;
393 if (full) {
394 increment_total_full_collections();
395 }
396 }
397
398 void increment_total_full_collections() { _total_full_collections++; }
399
400 // Return the SoftRefPolicy for the heap;
401 virtual SoftRefPolicy* soft_ref_policy() = 0;
402
403 virtual MemoryUsage memory_usage();
404 virtual GrowableArray<GCMemoryManager*> memory_managers() = 0;
405 virtual GrowableArray<MemoryPool*> memory_pools() = 0;
406
407 // Iterate over all objects, calling "cl.do_object" on each.
408 virtual void object_iterate(ObjectClosure* cl) = 0;
409
410 // Keep alive an object that was loaded with AS_NO_KEEPALIVE.
411 virtual void keep_alive(oop obj) {}
412
413 // Perform any cleanup actions necessary before allowing a verification.
414 virtual void prepare_for_verify() = 0;
415
416 // Returns the longest time (in ms) that has elapsed since the last
417 // time that the whole heap has been examined by a garbage collection.
418 jlong millis_since_last_whole_heap_examined();
419 // GC should call this when the next whole heap analysis has completed to
420 // satisfy above requirement.
421 void record_whole_heap_examined_timestamp();
422
423 private:
424 // Generate any dumps preceding or following a full gc
425 void full_gc_dump(GCTimer* timer, bool before);
426
427 virtual void initialize_serviceability() = 0;
428
429 public:
430 void pre_full_gc_dump(GCTimer* timer);
431 void post_full_gc_dump(GCTimer* timer);
432
433 virtual VirtualSpaceSummary create_heap_space_summary();
434 GCHeapSummary create_heap_summary();
435
436 MetaspaceSummary create_metaspace_summary();
437
438 // Print heap information on the given outputStream.
439 virtual void print_on(outputStream* st) const = 0;
440 // The default behavior is to call print_on() on tty.
441 virtual void print() const;
442
443 // Print more detailed heap information on the given
444 // outputStream. The default behavior is to call print_on(). It is
445 // up to each subclass to override it and add any additional output
446 // it needs.
447 virtual void print_extended_on(outputStream* st) const {
448 print_on(st);
449 }
450
451 virtual void print_on_error(outputStream* st) const;
452
453 // Used to print information about locations in the hs_err file.
454 virtual bool print_location(outputStream* st, void* addr) const = 0;
455
456 // Iterator for all GC threads (other than VM thread)
457 virtual void gc_threads_do(ThreadClosure* tc) const = 0;
458
459 // Print any relevant tracing info that flags imply.
460 // Default implementation does nothing.
461 virtual void print_tracing_info() const = 0;
462
463 void print_heap_before_gc();
464 void print_heap_after_gc();
465
466 // Registering and unregistering an nmethod (compiled code) with the heap.
467 virtual void register_nmethod(nmethod* nm) = 0;
468 virtual void unregister_nmethod(nmethod* nm) = 0;
469 // Callback for when nmethod is about to be deleted.
470 virtual void flush_nmethod(nmethod* nm) = 0;
471 virtual void verify_nmethod(nmethod* nm) = 0;
472
473 void trace_heap_before_gc(const GCTracer* gc_tracer);
474 void trace_heap_after_gc(const GCTracer* gc_tracer);
475
476 // Heap verification
477 virtual void verify(VerifyOption option) = 0;
478
479 // Return true if concurrent gc control via WhiteBox is supported by
480 // this collector. The default implementation returns false.
481 virtual bool supports_concurrent_gc_breakpoints() const;
482
483 // Provides a thread pool to SafepointSynchronize to use
484 // for parallel safepoint cleanup.
485 // GCs that use a GC worker thread pool may want to share
486 // it for use during safepoint cleanup. This is only possible
487 // if the GC can pause and resume concurrent work (e.g. G1
488 // concurrent marking) for an intermittent non-GC safepoint.
489 // If this method returns NULL, SafepointSynchronize will
490 // perform cleanup tasks serially in the VMThread.
491 virtual WorkGang* get_safepoint_workers() { return NULL; }
492
493 // Support for object pinning. This is used by JNI Get*Critical()
494 // and Release*Critical() family of functions. If supported, the GC
495 // must guarantee that pinned objects never move.
496 virtual bool supports_object_pinning() const;
497 virtual oop pin_object(JavaThread* thread, oop obj);
498 virtual void unpin_object(JavaThread* thread, oop obj);
499
500 // Deduplicate the string, iff the GC supports string deduplication.
501 virtual void deduplicate_string(oop str);
502
503 virtual bool is_oop(oop object) const;
504
505 // Non product verification and debugging.
506 #ifndef PRODUCT
507 // Support for PromotionFailureALot. Return true if it's time to cause a
508 // promotion failure. The no-argument version uses
509 // this->_promotion_failure_alot_count as the counter.
510 bool promotion_should_fail(volatile size_t* count);
511 bool promotion_should_fail();
512
513 // Reset the PromotionFailureALot counters. Should be called at the end of a
514 // GC in which promotion failure occurred.
515 void reset_promotion_should_fail(volatile size_t* count);
516 void reset_promotion_should_fail();
517 #endif // #ifndef PRODUCT
518 };
519
520 // Class to set and reset the GC cause for a CollectedHeap.
521
522 class GCCauseSetter : StackObj {
523 CollectedHeap* _heap;
524 GCCause::Cause _previous_cause;
525 public:
526 GCCauseSetter(CollectedHeap* heap, GCCause::Cause cause) {
527 _heap = heap;
528 _previous_cause = _heap->gc_cause();
529 _heap->set_gc_cause(cause);
530 }
531
532 ~GCCauseSetter() {
533 _heap->set_gc_cause(_previous_cause);
534 }
535 };
536
537 #endif // SHARE_GC_SHARED_COLLECTEDHEAP_HPP