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
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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/objectMarker.hpp"
31 #include "gc/shared/verifyOption.hpp"
32 #include "memory/allocation.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 unsigned int _total_collections; // ... started
116 unsigned int _total_full_collections; // ... started
117 NOT_PRODUCT(volatile size_t _promotion_failure_alot_count;)
118 NOT_PRODUCT(volatile size_t _promotion_failure_alot_gc_number;)
119
120 // Reason for current garbage collection. Should be set to
121 // a value reflecting no collection between collections.
122 GCCause::Cause _gc_cause;
123 GCCause::Cause _gc_lastcause;
124 PerfStringVariable* _perf_gc_cause;
125 PerfStringVariable* _perf_gc_lastcause;
126
127 // Constructor
128 CollectedHeap();
129
130 // Create a new tlab. All TLAB allocations must go through this.
131 // To allow more flexible TLAB allocations min_size specifies
132 // the minimum size needed, while requested_size is the requested
133 // size based on ergonomics. The actually allocated size will be
134 // returned in actual_size.
135 virtual HeapWord* allocate_new_tlab(size_t min_size,
136 size_t requested_size,
137 size_t* actual_size);
138
139 // Reinitialize tlabs before resuming mutators.
140 virtual void resize_all_tlabs();
141
142 // Raw memory allocation facilities
143 // The obj and array allocate methods are covers for these methods.
144 // mem_allocate() should never be
145 // called to allocate TLABs, only individual objects.
146 virtual HeapWord* mem_allocate(size_t size,
147 bool* gc_overhead_limit_was_exceeded) = 0;
148
149 // Filler object utilities.
150 static inline size_t filler_array_hdr_size();
151 static inline size_t filler_array_min_size();
152
153 DEBUG_ONLY(static void fill_args_check(HeapWord* start, size_t words);)
154 DEBUG_ONLY(static void zap_filler_array(HeapWord* start, size_t words, bool zap = true);)
155
156 // Fill with a single array; caller must ensure filler_array_min_size() <=
157 // words <= filler_array_max_size().
158 static inline void fill_with_array(HeapWord* start, size_t words, bool zap = true);
159
160 // Fill with a single object (either an int array or a java.lang.Object).
161 static inline void fill_with_object_impl(HeapWord* start, size_t words, bool zap = true);
162
163 virtual void trace_heap(GCWhen::Type when, const GCTracer* tracer);
164
165 // Verification functions
166 virtual void check_for_non_bad_heap_word_value(HeapWord* addr, size_t size)
167 PRODUCT_RETURN;
168 debug_only(static void check_for_valid_allocation_state();)
169
170 public:
171 enum Name {
172 None,
173 Serial,
174 Parallel,
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(const ReservedHeapSpace& rs);
208
209 virtual size_t capacity() const = 0;
210 virtual size_t used() const = 0;
211
212 // Returns unused capacity.
213 virtual size_t unused() const;
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" iff "p" points into the committed areas of the heap.
229 // This method can be expensive so avoid using it in performance critical
230 // code.
231 virtual bool is_in(const void* p) const = 0;
232
233 DEBUG_ONLY(bool is_in_or_null(const void* p) const { return p == NULL || is_in(p); })
234
235 virtual uint32_t hash_oop(oop obj) const;
236
237 void set_gc_cause(GCCause::Cause v) {
238 if (UsePerfData) {
239 _gc_lastcause = _gc_cause;
240 _perf_gc_lastcause->set_value(GCCause::to_string(_gc_lastcause));
241 _perf_gc_cause->set_value(GCCause::to_string(v));
242 }
243 _gc_cause = v;
244 }
245 GCCause::Cause gc_cause() { return _gc_cause; }
246
247 oop obj_allocate(Klass* klass, int size, TRAPS);
248 virtual oop array_allocate(Klass* klass, int size, int length, bool do_zero, TRAPS);
249 oop class_allocate(Klass* klass, int size, TRAPS);
250
251 // Utilities for turning raw memory into filler objects.
252 //
253 // min_fill_size() is the smallest region that can be filled.
254 // fill_with_objects() can fill arbitrary-sized regions of the heap using
255 // multiple objects. fill_with_object() is for regions known to be smaller
256 // than the largest array of integers; it uses a single object to fill the
257 // region and has slightly less overhead.
258 static size_t min_fill_size() {
259 return size_t(align_object_size(oopDesc::header_size()));
260 }
261
262 static void fill_with_objects(HeapWord* start, size_t words, bool zap = true);
263
264 static void fill_with_object(HeapWord* start, size_t words, bool zap = true);
265 static void fill_with_object(MemRegion region, bool zap = true) {
266 fill_with_object(region.start(), region.word_size(), zap);
267 }
268 static void fill_with_object(HeapWord* start, HeapWord* end, bool zap = true) {
269 fill_with_object(start, pointer_delta(end, start), zap);
270 }
271
272 virtual void fill_with_dummy_object(HeapWord* start, HeapWord* end, bool zap);
273 virtual size_t min_dummy_object_size() const;
274 size_t tlab_alloc_reserve() const;
275
276 // Return the address "addr" aligned by "alignment_in_bytes" if such
277 // an address is below "end". Return NULL otherwise.
278 inline static HeapWord* align_allocation_or_fail(HeapWord* addr,
279 HeapWord* end,
280 unsigned short alignment_in_bytes);
281
282 // Some heaps may offer a contiguous region for shared non-blocking
283 // allocation, via inlined code (by exporting the address of the top and
284 // end fields defining the extent of the contiguous allocation region.)
285
286 // This function returns "true" iff the heap supports this kind of
287 // allocation. (Default is "no".)
288 virtual bool supports_inline_contig_alloc() const {
289 return false;
290 }
291 // These functions return the addresses of the fields that define the
292 // boundaries of the contiguous allocation area. (These fields should be
293 // physically near to one another.)
294 virtual HeapWord* volatile* top_addr() const {
295 guarantee(false, "inline contiguous allocation not supported");
296 return NULL;
297 }
298 virtual HeapWord** end_addr() const {
299 guarantee(false, "inline contiguous allocation not supported");
300 return NULL;
301 }
302
303 // Some heaps may be in an unparseable state at certain times between
304 // collections. This may be necessary for efficient implementation of
305 // certain allocation-related activities. Calling this function before
306 // attempting to parse a heap ensures that the heap is in a parsable
307 // state (provided other concurrent activity does not introduce
308 // unparsability). It is normally expected, therefore, that this
309 // method is invoked with the world stopped.
310 // NOTE: if you override this method, make sure you call
311 // super::ensure_parsability so that the non-generational
312 // part of the work gets done. See implementation of
313 // CollectedHeap::ensure_parsability and, for instance,
314 // that of GenCollectedHeap::ensure_parsability().
315 // The argument "retire_tlabs" controls whether existing TLABs
316 // are merely filled or also retired, thus preventing further
317 // allocation from them and necessitating allocation of new TLABs.
318 virtual void ensure_parsability(bool retire_tlabs);
319
320 // Section on thread-local allocation buffers (TLABs)
321 // If the heap supports thread-local allocation buffers, it should override
322 // the following methods:
323 // Returns "true" iff the heap supports thread-local allocation buffers.
324 // The default is "no".
325 virtual bool supports_tlab_allocation() const = 0;
326
327 // The amount of space available for thread-local allocation buffers.
328 virtual size_t tlab_capacity(Thread *thr) const = 0;
329
330 // The amount of used space for thread-local allocation buffers for the given thread.
331 virtual size_t tlab_used(Thread *thr) const = 0;
332
333 virtual size_t max_tlab_size() const;
334
335 // An estimate of the maximum allocation that could be performed
336 // for thread-local allocation buffers without triggering any
337 // collection or expansion activity.
338 virtual size_t unsafe_max_tlab_alloc(Thread *thr) const {
339 guarantee(false, "thread-local allocation buffers not supported");
340 return 0;
341 }
342
343 // Perform a collection of the heap; intended for use in implementing
344 // "System.gc". This probably implies as full a collection as the
345 // "CollectedHeap" supports.
346 virtual void collect(GCCause::Cause cause) = 0;
347
348 // Perform a full collection
349 virtual void do_full_collection(bool clear_all_soft_refs) = 0;
350
351 // This interface assumes that it's being called by the
352 // vm thread. It collects the heap assuming that the
353 // heap lock is already held and that we are executing in
354 // the context of the vm thread.
355 virtual void collect_as_vm_thread(GCCause::Cause cause);
356
357 virtual MetaWord* satisfy_failed_metadata_allocation(ClassLoaderData* loader_data,
358 size_t size,
359 Metaspace::MetadataType mdtype);
360
361 // Returns "true" iff there is a stop-world GC in progress. (I assume
362 // that it should answer "false" for the concurrent part of a concurrent
363 // collector -- dld).
364 bool is_gc_active() const { return _is_gc_active; }
365
366 // Total number of GC collections (started)
367 unsigned int total_collections() const { return _total_collections; }
368 unsigned int total_full_collections() const { return _total_full_collections;}
369
370 // Increment total number of GC collections (started)
371 void increment_total_collections(bool full = false) {
372 _total_collections++;
373 if (full) {
374 increment_total_full_collections();
375 }
376 }
377
378 void increment_total_full_collections() { _total_full_collections++; }
379
380 // Return the SoftRefPolicy for the heap;
381 virtual SoftRefPolicy* soft_ref_policy() = 0;
382
383 virtual MemoryUsage memory_usage();
384 virtual GrowableArray<GCMemoryManager*> memory_managers() = 0;
385 virtual GrowableArray<MemoryPool*> memory_pools() = 0;
386
387 // ObjectMarker for JVMTI heap walk
388 virtual ObjectMarker* object_marker();
389
390 // Iterate over all objects, calling "cl.do_object" on each.
391 virtual void object_iterate(ObjectClosure* cl) = 0;
392
393 // Keep alive an object that was loaded with AS_NO_KEEPALIVE.
394 virtual void keep_alive(oop obj) {}
395
396 // Returns the longest time (in ms) that has elapsed since the last
397 // time that any part of the heap was examined by a garbage collection.
398 virtual jlong millis_since_last_gc() = 0;
399
400 // Perform any cleanup actions necessary before allowing a verification.
401 virtual void prepare_for_verify() = 0;
402
403 // Generate any dumps preceding or following a full gc
404 private:
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 // Print all GC threads (other than the VM thread)
437 // used by this heap.
438 virtual void print_gc_threads_on(outputStream* st) const = 0;
439 // The default behavior is to call print_gc_threads_on() on tty.
440 void print_gc_threads() {
441 print_gc_threads_on(tty);
442 }
443 // Iterator for all GC threads (other than VM thread)
444 virtual void gc_threads_do(ThreadClosure* tc) const = 0;
445
446 // Print any relevant tracing info that flags imply.
447 // Default implementation does nothing.
448 virtual void print_tracing_info() const = 0;
449
450 void print_heap_before_gc();
451 void print_heap_after_gc();
452
453 // Registering and unregistering an nmethod (compiled code) with the heap.
454 virtual void register_nmethod(nmethod* nm) = 0;
455 virtual void unregister_nmethod(nmethod* nm) = 0;
456 // Callback for when nmethod is about to be deleted.
457 virtual void flush_nmethod(nmethod* nm) = 0;
458 virtual void verify_nmethod(nmethod* nm) = 0;
459
460 void trace_heap_before_gc(const GCTracer* gc_tracer);
461 void trace_heap_after_gc(const GCTracer* gc_tracer);
462
463 // Heap verification
464 virtual void verify(VerifyOption option) = 0;
465
466 // Return true if concurrent phase control (via
467 // request_concurrent_phase_control) is supported by this collector.
468 // The default implementation returns false.
469 virtual bool supports_concurrent_phase_control() const;
470
471 // Request the collector enter the indicated concurrent phase, and
472 // wait until it does so. Supports WhiteBox testing. Only one
473 // request may be active at a time. Phases are designated by name;
474 // the set of names and their meaning is GC-specific. Once the
475 // requested phase has been reached, the collector will attempt to
476 // avoid transitioning to a new phase until a new request is made.
477 // [Note: A collector might not be able to remain in a given phase.
478 // For example, a full collection might cancel an in-progress
479 // concurrent collection.]
480 //
481 // Returns true when the phase is reached. Returns false for an
482 // unknown phase. The default implementation returns false.
483 virtual bool request_concurrent_phase(const char* phase);
484
485 // Provides a thread pool to SafepointSynchronize to use
486 // for parallel safepoint cleanup.
487 // GCs that use a GC worker thread pool may want to share
488 // it for use during safepoint cleanup. This is only possible
489 // if the GC can pause and resume concurrent work (e.g. G1
490 // concurrent marking) for an intermittent non-GC safepoint.
491 // If this method returns NULL, SafepointSynchronize will
492 // perform cleanup tasks serially in the VMThread.
493 virtual WorkGang* get_safepoint_workers() { return NULL; }
494
495 // Support for object pinning. This is used by JNI Get*Critical()
496 // and Release*Critical() family of functions. If supported, the GC
497 // must guarantee that pinned objects never move.
498 virtual bool supports_object_pinning() const;
499 virtual oop pin_object(JavaThread* thread, oop obj);
500 virtual void unpin_object(JavaThread* thread, oop obj);
501
502 // Deduplicate the string, iff the GC supports string deduplication.
503 virtual void deduplicate_string(oop str);
504
505 virtual bool is_oop(oop object) const;
506
507 virtual size_t obj_size(oop obj) const;
508
509 // Non product verification and debugging.
510 #ifndef PRODUCT
511 // Support for PromotionFailureALot. Return true if it's time to cause a
512 // promotion failure. The no-argument version uses
513 // this->_promotion_failure_alot_count as the counter.
514 bool promotion_should_fail(volatile size_t* count);
515 bool promotion_should_fail();
516
517 // Reset the PromotionFailureALot counters. Should be called at the end of a
518 // GC in which promotion failure occurred.
519 void reset_promotion_should_fail(volatile size_t* count);
520 void reset_promotion_should_fail();
521 #endif // #ifndef PRODUCT
522 };
523
524 // Class to set and reset the GC cause for a CollectedHeap.
525
526 class GCCauseSetter : StackObj {
527 CollectedHeap* _heap;
528 GCCause::Cause _previous_cause;
529 public:
530 GCCauseSetter(CollectedHeap* heap, GCCause::Cause cause) {
531 _heap = heap;
532 _previous_cause = _heap->gc_cause();
533 _heap->set_gc_cause(cause);
534 }
535
536 ~GCCauseSetter() {
537 _heap->set_gc_cause(_previous_cause);
538 }
539 };
540
541 #endif // SHARE_GC_SHARED_COLLECTEDHEAP_HPP