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 ParallelObjectIterator : public CHeapObj<mtGC> {
66 public:
67 virtual void object_iterate(ObjectClosure* cl, uint worker_id) = 0;
68 virtual ~ParallelObjectIterator() {}
69 };
70
71 //
72 // CollectedHeap
73 // GenCollectedHeap
74 // SerialHeap
75 // G1CollectedHeap
76 // ParallelScavengeHeap
77 // ShenandoahHeap
78 // ZCollectedHeap
79 //
80 class CollectedHeap : public CHeapObj<mtGC> {
81 friend class VMStructs;
82 friend class JVMCIVMStructs;
83 friend class IsGCActiveMark; // Block structured external access to _is_gc_active
84 friend class MemAllocator;
85
86 private:
87 GCHeapLog* _gc_heap_log;
88
89 // Historic gc information
90 size_t _capacity_at_last_gc;
91 size_t _used_at_last_gc;
92
93 protected:
94 // Not used by all GCs
95 MemRegion _reserved;
96
97 bool _is_gc_active;
98
99 // Used for filler objects (static, but initialized in ctor).
100 static size_t _filler_array_max_size;
101
102 // Last time the whole heap has been examined in support of RMI
103 // MaxObjectInspectionAge.
104 // This timestamp must be monotonically non-decreasing to avoid
105 // time-warp warnings.
106 jlong _last_whole_heap_examined_time_ns;
107
108 unsigned int _total_collections; // ... started
109 unsigned int _total_full_collections; // ... started
110 NOT_PRODUCT(volatile size_t _promotion_failure_alot_count;)
111 NOT_PRODUCT(volatile size_t _promotion_failure_alot_gc_number;)
112
113 // Reason for current garbage collection. Should be set to
114 // a value reflecting no collection between collections.
115 GCCause::Cause _gc_cause;
116 GCCause::Cause _gc_lastcause;
117 PerfStringVariable* _perf_gc_cause;
118 PerfStringVariable* _perf_gc_lastcause;
119
120 // Constructor
121 CollectedHeap();
122
123 // Create a new tlab. All TLAB allocations must go through this.
124 // To allow more flexible TLAB allocations min_size specifies
125 // the minimum size needed, while requested_size is the requested
126 // size based on ergonomics. The actually allocated size will be
127 // returned in actual_size.
128 virtual HeapWord* allocate_new_tlab(size_t min_size,
129 size_t requested_size,
130 size_t* actual_size);
131
132 // Reinitialize tlabs before resuming mutators.
133 virtual void resize_all_tlabs();
134
135 // Raw memory allocation facilities
136 // The obj and array allocate methods are covers for these methods.
137 // mem_allocate() should never be
138 // called to allocate TLABs, only individual objects.
139 virtual HeapWord* mem_allocate(size_t size,
140 bool* gc_overhead_limit_was_exceeded) = 0;
141
142 // Filler object utilities.
143 static inline size_t filler_array_min_size();
144
145 DEBUG_ONLY(static void fill_args_check(HeapWord* start, size_t words);)
146 DEBUG_ONLY(static void zap_filler_array(HeapWord* start, size_t words, bool zap = true);)
147
148 // Fill with a single array; caller must ensure filler_array_min_size() <=
149 // words <= filler_array_max_size().
150 static inline void fill_with_array(HeapWord* start, size_t words, bool zap = true);
151
152 // Fill with a single object (either an int array or a java.lang.Object).
153 static inline void fill_with_object_impl(HeapWord* start, size_t words, bool zap = true);
154
155 virtual void trace_heap(GCWhen::Type when, const GCTracer* tracer);
156
157 // Verification functions
158 virtual void check_for_non_bad_heap_word_value(HeapWord* addr, size_t size)
159 PRODUCT_RETURN;
160 debug_only(static void check_for_valid_allocation_state();)
161
162 public:
163 enum Name {
164 None,
165 Serial,
166 Parallel,
167 G1,
168 Epsilon,
169 Z,
170 Shenandoah
171 };
172
173 protected:
174 // Get a pointer to the derived heap object. Used to implement
175 // derived class heap() functions rather than being called directly.
176 template<typename T>
177 static T* named_heap(Name kind) {
178 CollectedHeap* heap = Universe::heap();
179 assert(heap != NULL, "Uninitialized heap");
180 assert(kind == heap->kind(), "Heap kind %u should be %u",
181 static_cast<uint>(heap->kind()), static_cast<uint>(kind));
182 return static_cast<T*>(heap);
183 }
184
185 public:
186
187 static inline size_t filler_array_max_size() {
188 return _filler_array_max_size;
189 }
190
191 virtual Name kind() const = 0;
192
193 virtual const char* name() const = 0;
194
195 /**
196 * Returns JNI error code JNI_ENOMEM if memory could not be allocated,
197 * and JNI_OK on success.
198 */
199 virtual jint initialize() = 0;
200
201 // In many heaps, there will be a need to perform some initialization activities
202 // after the Universe is fully formed, but before general heap allocation is allowed.
203 // This is the correct place to place such initialization methods.
204 virtual void post_initialize();
205
206 // Stop any onging concurrent work and prepare for exit.
207 virtual void stop() {}
208
209 // Stop and resume concurrent GC threads interfering with safepoint operations
210 virtual void safepoint_synchronize_begin() {}
211 virtual void safepoint_synchronize_end() {}
212
213 void initialize_reserved_region(const ReservedHeapSpace& rs);
214
215 virtual size_t capacity() const = 0;
216 virtual size_t used() const = 0;
217
218 // Returns unused capacity.
219 virtual size_t unused() const;
220
221 // Historic gc information
222 size_t free_at_last_gc() const { return _capacity_at_last_gc - _used_at_last_gc; }
223 size_t used_at_last_gc() const { return _used_at_last_gc; }
224 void update_capacity_and_used_at_gc();
225
226 // Return "true" if the part of the heap that allocates Java
227 // objects has reached the maximal committed limit that it can
228 // reach, without a garbage collection.
229 virtual bool is_maximal_no_gc() const = 0;
230
231 // Support for java.lang.Runtime.maxMemory(): return the maximum amount of
232 // memory that the vm could make available for storing 'normal' java objects.
233 // This is based on the reserved address space, but should not include space
234 // that the vm uses internally for bookkeeping or temporary storage
235 // (e.g., in the case of the young gen, one of the survivor
236 // spaces).
237 virtual size_t max_capacity() const = 0;
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 GCCause::Cause gc_cause() { return _gc_cause; }
250
251 oop obj_allocate(Klass* klass, int size, TRAPS);
252 virtual oop array_allocate(Klass* klass, int size, int length, bool do_zero, TRAPS);
253 oop class_allocate(Klass* klass, int size, TRAPS);
254
255 // Utilities for turning raw memory into filler objects.
256 //
257 // min_fill_size() is the smallest region that can be filled.
258 // fill_with_objects() can fill arbitrary-sized regions of the heap using
259 // multiple objects. fill_with_object() is for regions known to be smaller
260 // than the largest array of integers; it uses a single object to fill the
261 // region and has slightly less overhead.
262 static size_t min_fill_size() {
263 return size_t(align_object_size(oopDesc::header_size()));
264 }
265
266 static void fill_with_objects(HeapWord* start, size_t words, bool zap = true);
267
268 static void fill_with_object(HeapWord* start, size_t words, bool zap = true);
269 static void fill_with_object(MemRegion region, bool zap = true) {
270 fill_with_object(region.start(), region.word_size(), zap);
271 }
272 static void fill_with_object(HeapWord* start, HeapWord* end, bool zap = true) {
273 fill_with_object(start, pointer_delta(end, start), zap);
274 }
275
276 virtual void fill_with_dummy_object(HeapWord* start, HeapWord* end, bool zap);
277 virtual size_t min_dummy_object_size() const;
278 size_t tlab_alloc_reserve() const;
279
280 // Some heaps may offer a contiguous region for shared non-blocking
281 // allocation, via inlined code (by exporting the address of the top and
282 // end fields defining the extent of the contiguous allocation region.)
283
284 // This function returns "true" iff the heap supports this kind of
285 // allocation. (Default is "no".)
286 virtual bool supports_inline_contig_alloc() const {
287 return false;
288 }
289 // These functions return the addresses of the fields that define the
290 // boundaries of the contiguous allocation area. (These fields should be
291 // physically near to one another.)
292 virtual HeapWord* volatile* top_addr() const {
293 guarantee(false, "inline contiguous allocation not supported");
294 return NULL;
295 }
296 virtual HeapWord** end_addr() const {
297 guarantee(false, "inline contiguous allocation not supported");
298 return NULL;
299 }
300
301 // Some heaps may be in an unparseable state at certain times between
302 // collections. This may be necessary for efficient implementation of
303 // certain allocation-related activities. Calling this function before
304 // attempting to parse a heap ensures that the heap is in a parsable
305 // state (provided other concurrent activity does not introduce
306 // unparsability). It is normally expected, therefore, that this
307 // method is invoked with the world stopped.
308 // NOTE: if you override this method, make sure you call
309 // super::ensure_parsability so that the non-generational
310 // part of the work gets done. See implementation of
311 // CollectedHeap::ensure_parsability and, for instance,
312 // that of GenCollectedHeap::ensure_parsability().
313 // The argument "retire_tlabs" controls whether existing TLABs
314 // are merely filled or also retired, thus preventing further
315 // allocation from them and necessitating allocation of new TLABs.
316 virtual void ensure_parsability(bool retire_tlabs);
317
318 // The amount of space available for thread-local allocation buffers.
319 virtual size_t tlab_capacity(Thread *thr) const = 0;
320
321 // The amount of used space for thread-local allocation buffers for the given thread.
322 virtual size_t tlab_used(Thread *thr) const = 0;
323
324 virtual size_t max_tlab_size() const;
325
326 // An estimate of the maximum allocation that could be performed
327 // for thread-local allocation buffers without triggering any
328 // collection or expansion activity.
329 virtual size_t unsafe_max_tlab_alloc(Thread *thr) const {
330 guarantee(false, "thread-local allocation buffers not supported");
331 return 0;
332 }
333
334 // If a GC uses a stack watermark barrier, the stack processing is lazy, concurrent,
335 // incremental and cooperative. In order for that to work well, mechanisms that stop
336 // another thread might want to ensure its roots are in a sane state.
337 virtual bool uses_stack_watermark_barrier() const { return false; }
338
339 // Perform a collection of the heap; intended for use in implementing
340 // "System.gc". This probably implies as full a collection as the
341 // "CollectedHeap" supports.
342 virtual void collect(GCCause::Cause cause) = 0;
343
344 // Perform a full collection
345 virtual void do_full_collection(bool clear_all_soft_refs) = 0;
346
347 // This interface assumes that it's being called by the
348 // vm thread. It collects the heap assuming that the
349 // heap lock is already held and that we are executing in
350 // the context of the vm thread.
351 virtual void collect_as_vm_thread(GCCause::Cause cause);
352
353 virtual MetaWord* satisfy_failed_metadata_allocation(ClassLoaderData* loader_data,
354 size_t size,
355 Metaspace::MetadataType mdtype);
356
357 // Returns "true" iff there is a stop-world GC in progress. (I assume
358 // that it should answer "false" for the concurrent part of a concurrent
359 // collector -- dld).
360 bool is_gc_active() const { return _is_gc_active; }
361
362 // Total number of GC collections (started)
363 unsigned int total_collections() const { return _total_collections; }
364 unsigned int total_full_collections() const { return _total_full_collections;}
365
366 // Increment total number of GC collections (started)
367 void increment_total_collections(bool full = false) {
368 _total_collections++;
369 if (full) {
370 increment_total_full_collections();
371 }
372 }
373
374 void increment_total_full_collections() { _total_full_collections++; }
375
376 // Return the SoftRefPolicy for the heap;
377 virtual SoftRefPolicy* soft_ref_policy() = 0;
378
379 virtual MemoryUsage memory_usage();
380 virtual GrowableArray<GCMemoryManager*> memory_managers() = 0;
381 virtual GrowableArray<MemoryPool*> memory_pools() = 0;
382
383 // Iterate over all objects, calling "cl.do_object" on each.
384 virtual void object_iterate(ObjectClosure* cl) = 0;
385
386 virtual ParallelObjectIterator* parallel_object_iterator(uint thread_num) {
387 return NULL;
388 }
389
390 // Keep alive an object that was loaded with AS_NO_KEEPALIVE.
391 virtual void keep_alive(oop obj) {}
392
393 // Perform any cleanup actions necessary before allowing a verification.
394 virtual void prepare_for_verify() = 0;
395
396 // Returns the longest time (in ms) that has elapsed since the last
397 // time that the whole heap has been examined by a garbage collection.
398 jlong millis_since_last_whole_heap_examined();
399 // GC should call this when the next whole heap analysis has completed to
400 // satisfy above requirement.
401 void record_whole_heap_examined_timestamp();
402
403 private:
404 // Generate any dumps preceding or following a full gc
405 void full_gc_dump(GCTimer* timer, bool before);
406
407 virtual void initialize_serviceability() = 0;
408
409 public:
410 void pre_full_gc_dump(GCTimer* timer);
411 void post_full_gc_dump(GCTimer* timer);
412
413 virtual VirtualSpaceSummary create_heap_space_summary();
414 GCHeapSummary create_heap_summary();
415
416 MetaspaceSummary create_metaspace_summary();
417
418 // Print heap information on the given outputStream.
419 virtual void print_on(outputStream* st) const = 0;
420 // The default behavior is to call print_on() on tty.
421 virtual void print() const;
422
423 // Print more detailed heap information on the given
424 // outputStream. The default behavior is to call print_on(). It is
425 // up to each subclass to override it and add any additional output
426 // it needs.
427 virtual void print_extended_on(outputStream* st) const {
428 print_on(st);
429 }
430
431 virtual void print_on_error(outputStream* st) const;
432
433 // Used to print information about locations in the hs_err file.
434 virtual bool print_location(outputStream* st, void* addr) const = 0;
435
436 // Iterator for all GC threads (other than VM thread)
437 virtual void gc_threads_do(ThreadClosure* tc) const = 0;
438
439 // Print any relevant tracing info that flags imply.
440 // Default implementation does nothing.
441 virtual void print_tracing_info() const = 0;
442
443 void print_heap_before_gc();
444 void print_heap_after_gc();
445
446 // Registering and unregistering an nmethod (compiled code) with the heap.
447 virtual void register_nmethod(nmethod* nm) = 0;
448 virtual void unregister_nmethod(nmethod* nm) = 0;
449 // Callback for when nmethod is about to be deleted.
450 virtual void flush_nmethod(nmethod* nm) = 0;
451 virtual void verify_nmethod(nmethod* nm) = 0;
452
453 void trace_heap_before_gc(const GCTracer* gc_tracer);
454 void trace_heap_after_gc(const GCTracer* gc_tracer);
455
456 // Heap verification
457 virtual void verify(VerifyOption option) = 0;
458
459 // Return true if concurrent gc control via WhiteBox is supported by
460 // this collector. The default implementation returns false.
461 virtual bool supports_concurrent_gc_breakpoints() const;
462
463 // Provides a thread pool to SafepointSynchronize to use
464 // for parallel safepoint cleanup.
465 // GCs that use a GC worker thread pool may want to share
466 // it for use during safepoint cleanup. This is only possible
467 // if the GC can pause and resume concurrent work (e.g. G1
468 // concurrent marking) for an intermittent non-GC safepoint.
469 // If this method returns NULL, SafepointSynchronize will
470 // perform cleanup tasks serially in the VMThread.
471 virtual WorkGang* safepoint_workers() { return NULL; }
472
473 // Support for object pinning. This is used by JNI Get*Critical()
474 // and Release*Critical() family of functions. If supported, the GC
475 // must guarantee that pinned objects never move.
476 virtual bool supports_object_pinning() const;
477 virtual oop pin_object(JavaThread* thread, oop obj);
478 virtual void unpin_object(JavaThread* thread, oop obj);
479
480 // Is the given object inside a CDS archive area?
481 virtual bool is_archived_object(oop object) const;
482
483 virtual bool is_oop(oop object) const;
484 // Non product verification and debugging.
485 #ifndef PRODUCT
486 // Support for PromotionFailureALot. Return true if it's time to cause a
487 // promotion failure. The no-argument version uses
488 // this->_promotion_failure_alot_count as the counter.
489 bool promotion_should_fail(volatile size_t* count);
490 bool promotion_should_fail();
491
492 // Reset the PromotionFailureALot counters. Should be called at the end of a
493 // GC in which promotion failure occurred.
494 void reset_promotion_should_fail(volatile size_t* count);
495 void reset_promotion_should_fail();
496 #endif // #ifndef PRODUCT
497 };
498
499 // Class to set and reset the GC cause for a CollectedHeap.
500
501 class GCCauseSetter : StackObj {
502 CollectedHeap* _heap;
503 GCCause::Cause _previous_cause;
504 public:
505 GCCauseSetter(CollectedHeap* heap, GCCause::Cause cause) {
506 _heap = heap;
507 _previous_cause = _heap->gc_cause();
508 _heap->set_gc_cause(cause);
509 }
510
511 ~GCCauseSetter() {
512 _heap->set_gc_cause(_previous_cause);
513 }
514 };
515
516 #endif // SHARE_GC_SHARED_COLLECTEDHEAP_HPP