1 /*
2 * Copyright (c) 2001, 2022, 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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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.hpp"
33 #include "memory/universe.hpp"
34 #include "runtime/handles.hpp"
35 #include "runtime/perfDataTypes.hpp"
36 #include "runtime/safepoint.hpp"
37 #include "services/memoryUsage.hpp"
38 #include "utilities/debug.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 AbstractGangTask;
48 class AdaptiveSizePolicy;
49 class BarrierSet;
50 class GCHeapLog;
51 class GCHeapSummary;
52 class GCTimer;
53 class GCTracer;
54 class GCMemoryManager;
55 class MemoryPool;
56 class MetaspaceSummary;
57 class ReservedHeapSpace;
58 class SoftRefPolicy;
59 class Thread;
60 class ThreadClosure;
61 class VirtualSpaceSummary;
62 class WorkGang;
63 class nmethod;
64
65 class ParallelObjectIteratorImpl : public CHeapObj<mtGC> {
66 public:
67 virtual ~ParallelObjectIteratorImpl() {}
68 virtual void object_iterate(ObjectClosure* cl, uint worker_id) = 0;
69 };
70
71 // User facing parallel object iterator. This is a StackObj, which ensures that
72 // the _impl is allocated and deleted in the scope of this object. This ensures
73 // the life cycle of the implementation is as required by ThreadsListHandle,
74 // which is sometimes used by the root iterators.
75 class ParallelObjectIterator : public StackObj {
76 ParallelObjectIteratorImpl* _impl;
77
78 public:
79 ParallelObjectIterator(uint thread_num);
80 ~ParallelObjectIterator();
81 void object_iterate(ObjectClosure* cl, uint worker_id);
82 };
83
84 //
85 // CollectedHeap
86 // GenCollectedHeap
87 // SerialHeap
88 // G1CollectedHeap
89 // ParallelScavengeHeap
90 // ShenandoahHeap
91 // ZCollectedHeap
92 //
93 class CollectedHeap : public CHeapObj<mtGC> {
94 friend class VMStructs;
95 friend class JVMCIVMStructs;
96 friend class IsGCActiveMark; // Block structured external access to _is_gc_active
97 friend class MemAllocator;
98 friend class ParallelObjectIterator;
99
100 private:
101 GCHeapLog* _gc_heap_log;
102
103 // Historic gc information
104 size_t _capacity_at_last_gc;
105 size_t _used_at_last_gc;
106
107 protected:
108 // Not used by all GCs
109 MemRegion _reserved;
110
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 // Last time the whole heap has been examined in support of RMI
117 // MaxObjectInspectionAge.
118 // This timestamp must be monotonically non-decreasing to avoid
119 // time-warp warnings.
120 jlong _last_whole_heap_examined_time_ns;
121
122 unsigned int _total_collections; // ... started
123 unsigned int _total_full_collections; // ... started
124 NOT_PRODUCT(volatile size_t _promotion_failure_alot_count;)
125 NOT_PRODUCT(volatile size_t _promotion_failure_alot_gc_number;)
126
127 // Reason for current garbage collection. Should be set to
128 // a value reflecting no collection between collections.
129 GCCause::Cause _gc_cause;
130 GCCause::Cause _gc_lastcause;
131 PerfStringVariable* _perf_gc_cause;
132 PerfStringVariable* _perf_gc_lastcause;
133
134 // Constructor
135 CollectedHeap();
136
137 // Create a new tlab. All TLAB allocations must go through this.
138 // To allow more flexible TLAB allocations min_size specifies
139 // the minimum size needed, while requested_size is the requested
140 // size based on ergonomics. The actually allocated size will be
141 // returned in actual_size.
142 virtual HeapWord* allocate_new_tlab(size_t min_size,
143 size_t requested_size,
144 size_t* actual_size);
145
146 // Reinitialize tlabs before resuming mutators.
147 virtual void resize_all_tlabs();
148
149 // Raw memory allocation facilities
150 // The obj and array allocate methods are covers for these methods.
151 // mem_allocate() should never be
152 // called to allocate TLABs, only individual objects.
153 virtual HeapWord* mem_allocate(size_t size,
154 bool* gc_overhead_limit_was_exceeded) = 0;
155
156 // Filler object utilities.
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 debug_only(static void check_for_valid_allocation_state();)
173
174 public:
175 enum Name {
176 None,
177 Serial,
178 Parallel,
179 G1,
180 Epsilon,
181 Z,
182 Shenandoah
183 };
184
185 protected:
186 // Get a pointer to the derived heap object. Used to implement
187 // derived class heap() functions rather than being called directly.
188 template<typename T>
189 static T* named_heap(Name kind) {
190 CollectedHeap* heap = Universe::heap();
191 assert(heap != NULL, "Uninitialized heap");
192 assert(kind == heap->kind(), "Heap kind %u should be %u",
193 static_cast<uint>(heap->kind()), static_cast<uint>(kind));
194 return static_cast<T*>(heap);
195 }
196
197 public:
198
199 static inline size_t filler_array_max_size() {
200 return _filler_array_max_size;
201 }
202
203 virtual Name kind() const = 0;
204
205 virtual const char* name() const = 0;
206
207 /**
208 * Returns JNI error code JNI_ENOMEM if memory could not be allocated,
209 * and JNI_OK on success.
210 */
211 virtual jint initialize() = 0;
212
213 // In many heaps, there will be a need to perform some initialization activities
214 // after the Universe is fully formed, but before general heap allocation is allowed.
215 // This is the correct place to place such initialization methods.
216 virtual void post_initialize();
217
218 // Stop any onging concurrent work and prepare for exit.
219 virtual void stop() {}
220
221 // Stop and resume concurrent GC threads interfering with safepoint operations
222 virtual void safepoint_synchronize_begin() {}
223 virtual void safepoint_synchronize_end() {}
224
225 void initialize_reserved_region(const ReservedHeapSpace& rs);
226
227 virtual size_t capacity() const = 0;
228 virtual size_t used() const = 0;
229
230 // Returns unused capacity.
231 virtual size_t unused() const;
232
233 // Historic gc information
234 size_t free_at_last_gc() const { return _capacity_at_last_gc - _used_at_last_gc; }
235 size_t used_at_last_gc() const { return _used_at_last_gc; }
236 void update_capacity_and_used_at_gc();
237
238 // Return "true" if the part of the heap that allocates Java
239 // objects has reached the maximal committed limit that it can
240 // reach, without a garbage collection.
241 virtual bool is_maximal_no_gc() const = 0;
242
243 // Support for java.lang.Runtime.maxMemory(): return the maximum amount of
244 // memory that the vm could make available for storing 'normal' java objects.
245 // This is based on the reserved address space, but should not include space
246 // that the vm uses internally for bookkeeping or temporary storage
247 // (e.g., in the case of the young gen, one of the survivor
248 // spaces).
249 virtual size_t max_capacity() const = 0;
250
251 // Returns "TRUE" iff "p" points into the committed areas of the heap.
252 // This method can be expensive so avoid using it in performance critical
253 // code.
254 virtual bool is_in(const void* p) const = 0;
255
256 DEBUG_ONLY(bool is_in_or_null(const void* p) const { return p == NULL || is_in(p); })
257
258 virtual uint32_t hash_oop(oop obj) const;
259
260 void set_gc_cause(GCCause::Cause v);
261 GCCause::Cause gc_cause() { return _gc_cause; }
262
263 oop obj_allocate(Klass* klass, int size, TRAPS);
264 virtual oop array_allocate(Klass* klass, int size, int length, bool do_zero, TRAPS);
265 oop class_allocate(Klass* klass, int size, TRAPS);
266
267 // Utilities for turning raw memory into filler objects.
268 //
269 // min_fill_size() is the smallest region that can be filled.
270 // fill_with_objects() can fill arbitrary-sized regions of the heap using
271 // multiple objects. fill_with_object() is for regions known to be smaller
272 // than the largest array of integers; it uses a single object to fill the
273 // region and has slightly less overhead.
274 static size_t min_fill_size() {
275 return size_t(align_object_size(oopDesc::header_size()));
276 }
277
278 static void fill_with_objects(HeapWord* start, size_t words, bool zap = true);
279
280 static void fill_with_object(HeapWord* start, size_t words, bool zap = true);
281 static void fill_with_object(MemRegion region, bool zap = true) {
282 fill_with_object(region.start(), region.word_size(), zap);
283 }
284 static void fill_with_object(HeapWord* start, HeapWord* end, bool zap = true) {
285 fill_with_object(start, pointer_delta(end, start), zap);
286 }
287
288 virtual void fill_with_dummy_object(HeapWord* start, HeapWord* end, bool zap);
289 virtual size_t min_dummy_object_size() const;
290 size_t tlab_alloc_reserve() const;
291
292 // Some heaps may offer a contiguous region for shared non-blocking
293 // allocation, via inlined code (by exporting the address of the top and
294 // end fields defining the extent of the contiguous allocation region.)
295
296 // This function returns "true" iff the heap supports this kind of
297 // allocation. (Default is "no".)
298 virtual bool supports_inline_contig_alloc() const {
299 return false;
300 }
301 // These functions return the addresses of the fields that define the
302 // boundaries of the contiguous allocation area. (These fields should be
303 // physically near to one another.)
304 virtual HeapWord* volatile* top_addr() const {
305 guarantee(false, "inline contiguous allocation not supported");
306 return NULL;
307 }
308 virtual HeapWord** end_addr() const {
309 guarantee(false, "inline contiguous allocation not supported");
310 return NULL;
311 }
312
313 // Some heaps may be in an unparseable state at certain times between
314 // collections. This may be necessary for efficient implementation of
315 // certain allocation-related activities. Calling this function before
316 // attempting to parse a heap ensures that the heap is in a parsable
317 // state (provided other concurrent activity does not introduce
318 // unparsability). It is normally expected, therefore, that this
319 // method is invoked with the world stopped.
320 // NOTE: if you override this method, make sure you call
321 // super::ensure_parsability so that the non-generational
322 // part of the work gets done. See implementation of
323 // CollectedHeap::ensure_parsability and, for instance,
324 // that of GenCollectedHeap::ensure_parsability().
325 // The argument "retire_tlabs" controls whether existing TLABs
326 // are merely filled or also retired, thus preventing further
327 // allocation from them and necessitating allocation of new TLABs.
328 virtual void ensure_parsability(bool retire_tlabs);
329
330 // The amount of space available for thread-local allocation buffers.
331 virtual size_t tlab_capacity(Thread *thr) const = 0;
332
333 // The amount of used space for thread-local allocation buffers for the given thread.
334 virtual size_t tlab_used(Thread *thr) const = 0;
335
336 virtual size_t max_tlab_size() const;
337
338 // An estimate of the maximum allocation that could be performed
339 // for thread-local allocation buffers without triggering any
340 // collection or expansion activity.
341 virtual size_t unsafe_max_tlab_alloc(Thread *thr) const {
342 guarantee(false, "thread-local allocation buffers not supported");
343 return 0;
344 }
345
346 // If a GC uses a stack watermark barrier, the stack processing is lazy, concurrent,
347 // incremental and cooperative. In order for that to work well, mechanisms that stop
348 // another thread might want to ensure its roots are in a sane state.
349 virtual bool uses_stack_watermark_barrier() const { return false; }
350
351 // Perform a collection of the heap; intended for use in implementing
352 // "System.gc". This probably implies as full a collection as the
353 // "CollectedHeap" supports.
354 virtual void collect(GCCause::Cause cause) = 0;
355
356 // Perform a full collection
357 virtual void do_full_collection(bool clear_all_soft_refs) = 0;
358
359 // This interface assumes that it's being called by the
360 // vm thread. It collects the heap assuming that the
361 // heap lock is already held and that we are executing in
362 // the context of the vm thread.
363 virtual void collect_as_vm_thread(GCCause::Cause cause);
364
365 virtual MetaWord* satisfy_failed_metadata_allocation(ClassLoaderData* loader_data,
366 size_t size,
367 Metaspace::MetadataType mdtype);
368
369 // Returns "true" iff there is a stop-world GC in progress. (I assume
370 // that it should answer "false" for the concurrent part of a concurrent
371 // collector -- dld).
372 bool is_gc_active() const { return _is_gc_active; }
373
374 // Total number of GC collections (started)
375 unsigned int total_collections() const { return _total_collections; }
376 unsigned int total_full_collections() const { return _total_full_collections;}
377
378 // Increment total number of GC collections (started)
379 void increment_total_collections(bool full = false) {
380 _total_collections++;
381 if (full) {
382 increment_total_full_collections();
383 }
384 }
385
386 void increment_total_full_collections() { _total_full_collections++; }
387
388 // Return the SoftRefPolicy for the heap;
389 virtual SoftRefPolicy* soft_ref_policy() = 0;
390
391 virtual MemoryUsage memory_usage();
392 virtual GrowableArray<GCMemoryManager*> memory_managers() = 0;
393 virtual GrowableArray<MemoryPool*> memory_pools() = 0;
394
395 // Iterate over all objects, calling "cl.do_object" on each.
396 virtual void object_iterate(ObjectClosure* cl) = 0;
397
398 protected:
399 virtual ParallelObjectIteratorImpl* parallel_object_iterator(uint thread_num) {
400 return NULL;
401 }
402
403 public:
404 // Keep alive an object that was loaded with AS_NO_KEEPALIVE.
405 virtual void keep_alive(oop obj) {}
406
407 // Perform any cleanup actions necessary before allowing a verification.
408 virtual void prepare_for_verify() = 0;
409
410 // Returns the longest time (in ms) that has elapsed since the last
411 // time that the whole heap has been examined by a garbage collection.
412 jlong millis_since_last_whole_heap_examined();
413 // GC should call this when the next whole heap analysis has completed to
414 // satisfy above requirement.
415 void record_whole_heap_examined_timestamp();
416
417 private:
418 // Generate any dumps preceding or following a full gc
419 void full_gc_dump(GCTimer* timer, bool before);
420
421 virtual void initialize_serviceability() = 0;
422
423 public:
424 void pre_full_gc_dump(GCTimer* timer);
425 void post_full_gc_dump(GCTimer* timer);
426
427 virtual VirtualSpaceSummary create_heap_space_summary();
428 GCHeapSummary create_heap_summary();
429
430 MetaspaceSummary create_metaspace_summary();
431
432 // Print heap information on the given outputStream.
433 virtual void print_on(outputStream* st) const = 0;
434 // The default behavior is to call print_on() on tty.
435 virtual void print() const;
436
437 // Print more detailed heap information on the given
438 // outputStream. The default behavior is to call print_on(). It is
439 // up to each subclass to override it and add any additional output
440 // it needs.
441 virtual void print_extended_on(outputStream* st) const {
442 print_on(st);
443 }
444
445 virtual void print_on_error(outputStream* st) const;
446
447 // Used to print information about locations in the hs_err file.
448 virtual bool print_location(outputStream* st, void* addr) const = 0;
449
450 // Iterator for all GC threads (other than VM thread)
451 virtual void gc_threads_do(ThreadClosure* tc) const = 0;
452
453 // Print any relevant tracing info that flags imply.
454 // Default implementation does nothing.
455 virtual void print_tracing_info() const = 0;
456
457 void print_heap_before_gc();
458 void print_heap_after_gc();
459
460 // Registering and unregistering an nmethod (compiled code) with the heap.
461 virtual void register_nmethod(nmethod* nm) = 0;
462 virtual void unregister_nmethod(nmethod* nm) = 0;
463 // Callback for when nmethod is about to be deleted.
464 virtual void flush_nmethod(nmethod* nm) = 0;
465 virtual void verify_nmethod(nmethod* nm) = 0;
466
467 void trace_heap_before_gc(const GCTracer* gc_tracer);
468 void trace_heap_after_gc(const GCTracer* gc_tracer);
469
470 // Heap verification
471 virtual void verify(VerifyOption option) = 0;
472
473 // Return true if concurrent gc control via WhiteBox is supported by
474 // this collector. The default implementation returns false.
475 virtual bool supports_concurrent_gc_breakpoints() const;
476
477 // Provides a thread pool to SafepointSynchronize to use
478 // for parallel safepoint cleanup.
479 // GCs that use a GC worker thread pool may want to share
480 // it for use during safepoint cleanup. This is only possible
481 // if the GC can pause and resume concurrent work (e.g. G1
482 // concurrent marking) for an intermittent non-GC safepoint.
483 // If this method returns NULL, SafepointSynchronize will
484 // perform cleanup tasks serially in the VMThread.
485 virtual WorkGang* safepoint_workers() { return NULL; }
486
487 // Support for object pinning. This is used by JNI Get*Critical()
488 // and Release*Critical() family of functions. If supported, the GC
489 // must guarantee that pinned objects never move.
490 virtual bool supports_object_pinning() const;
491 virtual oop pin_object(JavaThread* thread, oop obj);
492 virtual void unpin_object(JavaThread* thread, oop obj);
493
494 // Is the given object inside a CDS archive area?
495 virtual bool is_archived_object(oop object) const;
496
497 virtual bool is_oop(oop object) const;
498 // Non product verification and debugging.
499 #ifndef PRODUCT
500 // Support for PromotionFailureALot. Return true if it's time to cause a
501 // promotion failure. The no-argument version uses
502 // this->_promotion_failure_alot_count as the counter.
503 bool promotion_should_fail(volatile size_t* count);
504 bool promotion_should_fail();
505
506 // Reset the PromotionFailureALot counters. Should be called at the end of a
507 // GC in which promotion failure occurred.
508 void reset_promotion_should_fail(volatile size_t* count);
509 void reset_promotion_should_fail();
510 #endif // #ifndef PRODUCT
511 };
512
513 // Class to set and reset the GC cause for a CollectedHeap.
514
515 class GCCauseSetter : StackObj {
516 CollectedHeap* _heap;
517 GCCause::Cause _previous_cause;
518 public:
519 GCCauseSetter(CollectedHeap* heap, GCCause::Cause cause) {
520 _heap = heap;
521 _previous_cause = _heap->gc_cause();
522 _heap->set_gc_cause(cause);
523 }
524
525 ~GCCauseSetter() {
526 _heap->set_gc_cause(_previous_cause);
527 }
528 };
529
530 #endif // SHARE_GC_SHARED_COLLECTEDHEAP_HPP