Wed, 01 Feb 2012 07:59:01 -0800
7141200: log some interesting information in ring buffers for crashes
Reviewed-by: kvn, jrose, kevinw, brutisso, twisti, jmasa
1 /*
2 * Copyright (c) 2001, 2012, 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 */
25 #ifndef SHARE_VM_GC_INTERFACE_COLLECTEDHEAP_HPP
26 #define SHARE_VM_GC_INTERFACE_COLLECTEDHEAP_HPP
28 #include "gc_interface/gcCause.hpp"
29 #include "memory/allocation.hpp"
30 #include "memory/barrierSet.hpp"
31 #include "runtime/handles.hpp"
32 #include "runtime/perfData.hpp"
33 #include "runtime/safepoint.hpp"
34 #include "utilities/events.hpp"
36 // A "CollectedHeap" is an implementation of a java heap for HotSpot. This
37 // is an abstract class: there may be many different kinds of heaps. This
38 // class defines the functions that a heap must implement, and contains
39 // infrastructure common to all heaps.
41 class BarrierSet;
42 class ThreadClosure;
43 class AdaptiveSizePolicy;
44 class Thread;
45 class CollectorPolicy;
47 class GCMessage : public FormatBuffer<1024> {
48 public:
49 bool is_before;
51 public:
52 GCMessage() {}
53 };
55 class GCHeapLog : public EventLogBase<GCMessage> {
56 private:
57 void log_heap(bool before);
59 public:
60 GCHeapLog() : EventLogBase<GCMessage>("GC Heap History") {}
62 void log_heap_before() {
63 log_heap(true);
64 }
65 void log_heap_after() {
66 log_heap(false);
67 }
68 };
70 //
71 // CollectedHeap
72 // SharedHeap
73 // GenCollectedHeap
74 // G1CollectedHeap
75 // ParallelScavengeHeap
76 //
77 class CollectedHeap : public CHeapObj {
78 friend class VMStructs;
79 friend class IsGCActiveMark; // Block structured external access to _is_gc_active
80 friend class constantPoolCacheKlass; // allocate() method inserts is_conc_safe
82 #ifdef ASSERT
83 static int _fire_out_of_memory_count;
84 #endif
86 // Used for filler objects (static, but initialized in ctor).
87 static size_t _filler_array_max_size;
89 GCHeapLog* _gc_heap_log;
91 // Used in support of ReduceInitialCardMarks; only consulted if COMPILER2 is being used
92 bool _defer_initial_card_mark;
94 protected:
95 MemRegion _reserved;
96 BarrierSet* _barrier_set;
97 bool _is_gc_active;
98 uint _n_par_threads;
100 unsigned int _total_collections; // ... started
101 unsigned int _total_full_collections; // ... started
102 NOT_PRODUCT(volatile size_t _promotion_failure_alot_count;)
103 NOT_PRODUCT(volatile size_t _promotion_failure_alot_gc_number;)
105 // Reason for current garbage collection. Should be set to
106 // a value reflecting no collection between collections.
107 GCCause::Cause _gc_cause;
108 GCCause::Cause _gc_lastcause;
109 PerfStringVariable* _perf_gc_cause;
110 PerfStringVariable* _perf_gc_lastcause;
112 // Constructor
113 CollectedHeap();
115 // Do common initializations that must follow instance construction,
116 // for example, those needing virtual calls.
117 // This code could perhaps be moved into initialize() but would
118 // be slightly more awkward because we want the latter to be a
119 // pure virtual.
120 void pre_initialize();
122 // Create a new tlab. All TLAB allocations must go through this.
123 virtual HeapWord* allocate_new_tlab(size_t size);
125 // Accumulate statistics on all tlabs.
126 virtual void accumulate_statistics_all_tlabs();
128 // Reinitialize tlabs before resuming mutators.
129 virtual void resize_all_tlabs();
131 protected:
132 // Allocate from the current thread's TLAB, with broken-out slow path.
133 inline static HeapWord* allocate_from_tlab(Thread* thread, size_t size);
134 static HeapWord* allocate_from_tlab_slow(Thread* thread, size_t size);
136 // Allocate an uninitialized block of the given size, or returns NULL if
137 // this is impossible.
138 inline static HeapWord* common_mem_allocate_noinit(size_t size, TRAPS);
140 // Like allocate_init, but the block returned by a successful allocation
141 // is guaranteed initialized to zeros.
142 inline static HeapWord* common_mem_allocate_init(size_t size, TRAPS);
144 // Same as common_mem version, except memory is allocated in the permanent area
145 // If there is no permanent area, revert to common_mem_allocate_noinit
146 inline static HeapWord* common_permanent_mem_allocate_noinit(size_t size, TRAPS);
148 // Same as common_mem version, except memory is allocated in the permanent area
149 // If there is no permanent area, revert to common_mem_allocate_init
150 inline static HeapWord* common_permanent_mem_allocate_init(size_t size, TRAPS);
152 // Helper functions for (VM) allocation.
153 inline static void post_allocation_setup_common(KlassHandle klass,
154 HeapWord* obj, size_t size);
155 inline static void post_allocation_setup_no_klass_install(KlassHandle klass,
156 HeapWord* objPtr,
157 size_t size);
159 inline static void post_allocation_setup_obj(KlassHandle klass,
160 HeapWord* obj, size_t size);
162 inline static void post_allocation_setup_array(KlassHandle klass,
163 HeapWord* obj, size_t size,
164 int length);
166 // Clears an allocated object.
167 inline static void init_obj(HeapWord* obj, size_t size);
169 // Filler object utilities.
170 static inline size_t filler_array_hdr_size();
171 static inline size_t filler_array_min_size();
172 static inline size_t filler_array_max_size();
174 DEBUG_ONLY(static void fill_args_check(HeapWord* start, size_t words);)
175 DEBUG_ONLY(static void zap_filler_array(HeapWord* start, size_t words, bool zap = true);)
177 // Fill with a single array; caller must ensure filler_array_min_size() <=
178 // words <= filler_array_max_size().
179 static inline void fill_with_array(HeapWord* start, size_t words, bool zap = true);
181 // Fill with a single object (either an int array or a java.lang.Object).
182 static inline void fill_with_object_impl(HeapWord* start, size_t words, bool zap = true);
184 // Verification functions
185 virtual void check_for_bad_heap_word_value(HeapWord* addr, size_t size)
186 PRODUCT_RETURN;
187 virtual void check_for_non_bad_heap_word_value(HeapWord* addr, size_t size)
188 PRODUCT_RETURN;
189 debug_only(static void check_for_valid_allocation_state();)
191 public:
192 enum Name {
193 Abstract,
194 SharedHeap,
195 GenCollectedHeap,
196 ParallelScavengeHeap,
197 G1CollectedHeap
198 };
200 virtual CollectedHeap::Name kind() const { return CollectedHeap::Abstract; }
202 /**
203 * Returns JNI error code JNI_ENOMEM if memory could not be allocated,
204 * and JNI_OK on success.
205 */
206 virtual jint initialize() = 0;
208 // In many heaps, there will be a need to perform some initialization activities
209 // after the Universe is fully formed, but before general heap allocation is allowed.
210 // This is the correct place to place such initialization methods.
211 virtual void post_initialize() = 0;
213 MemRegion reserved_region() const { return _reserved; }
214 address base() const { return (address)reserved_region().start(); }
216 // Future cleanup here. The following functions should specify bytes or
217 // heapwords as part of their signature.
218 virtual size_t capacity() const = 0;
219 virtual size_t used() const = 0;
221 // Return "true" if the part of the heap that allocates Java
222 // objects has reached the maximal committed limit that it can
223 // reach, without a garbage collection.
224 virtual bool is_maximal_no_gc() const = 0;
226 virtual size_t permanent_capacity() const = 0;
227 virtual size_t permanent_used() const = 0;
229 // Support for java.lang.Runtime.maxMemory(): return the maximum amount of
230 // memory that the vm could make available for storing 'normal' java objects.
231 // This is based on the reserved address space, but should not include space
232 // that the vm uses internally for bookkeeping or temporary storage (e.g.,
233 // perm gen space or, in the case of the young gen, one of the survivor
234 // spaces).
235 virtual size_t max_capacity() const = 0;
237 // Returns "TRUE" if "p" points into the reserved area of the heap.
238 bool is_in_reserved(const void* p) const {
239 return _reserved.contains(p);
240 }
242 bool is_in_reserved_or_null(const void* p) const {
243 return p == NULL || is_in_reserved(p);
244 }
246 // Returns "TRUE" iff "p" points into the committed areas of the heap.
247 // Since this method can be expensive in general, we restrict its
248 // use to assertion checking only.
249 virtual bool is_in(const void* p) const = 0;
251 bool is_in_or_null(const void* p) const {
252 return p == NULL || is_in(p);
253 }
255 // Let's define some terms: a "closed" subset of a heap is one that
256 //
257 // 1) contains all currently-allocated objects, and
258 //
259 // 2) is closed under reference: no object in the closed subset
260 // references one outside the closed subset.
261 //
262 // Membership in a heap's closed subset is useful for assertions.
263 // Clearly, the entire heap is a closed subset, so the default
264 // implementation is to use "is_in_reserved". But this may not be too
265 // liberal to perform useful checking. Also, the "is_in" predicate
266 // defines a closed subset, but may be too expensive, since "is_in"
267 // verifies that its argument points to an object head. The
268 // "closed_subset" method allows a heap to define an intermediate
269 // predicate, allowing more precise checking than "is_in_reserved" at
270 // lower cost than "is_in."
272 // One important case is a heap composed of disjoint contiguous spaces,
273 // such as the Garbage-First collector. Such heaps have a convenient
274 // closed subset consisting of the allocated portions of those
275 // contiguous spaces.
277 // Return "TRUE" iff the given pointer points into the heap's defined
278 // closed subset (which defaults to the entire heap).
279 virtual bool is_in_closed_subset(const void* p) const {
280 return is_in_reserved(p);
281 }
283 bool is_in_closed_subset_or_null(const void* p) const {
284 return p == NULL || is_in_closed_subset(p);
285 }
287 // XXX is_permanent() and is_in_permanent() should be better named
288 // to distinguish one from the other.
290 // Returns "TRUE" if "p" is allocated as "permanent" data.
291 // If the heap does not use "permanent" data, returns the same
292 // value is_in_reserved() would return.
293 // NOTE: this actually returns true if "p" is in reserved space
294 // for the space not that it is actually allocated (i.e. in committed
295 // space). If you need the more conservative answer use is_permanent().
296 virtual bool is_in_permanent(const void *p) const = 0;
299 #ifdef ASSERT
300 // Returns true if "p" is in the part of the
301 // heap being collected.
302 virtual bool is_in_partial_collection(const void *p) = 0;
303 #endif
305 bool is_in_permanent_or_null(const void *p) const {
306 return p == NULL || is_in_permanent(p);
307 }
309 // Returns "TRUE" if "p" is in the committed area of "permanent" data.
310 // If the heap does not use "permanent" data, returns the same
311 // value is_in() would return.
312 virtual bool is_permanent(const void *p) const = 0;
314 bool is_permanent_or_null(const void *p) const {
315 return p == NULL || is_permanent(p);
316 }
318 // An object is scavengable if its location may move during a scavenge.
319 // (A scavenge is a GC which is not a full GC.)
320 virtual bool is_scavengable(const void *p) = 0;
322 // Returns "TRUE" if "p" is a method oop in the
323 // current heap, with high probability. This predicate
324 // is not stable, in general.
325 bool is_valid_method(oop p) const;
327 void set_gc_cause(GCCause::Cause v) {
328 if (UsePerfData) {
329 _gc_lastcause = _gc_cause;
330 _perf_gc_lastcause->set_value(GCCause::to_string(_gc_lastcause));
331 _perf_gc_cause->set_value(GCCause::to_string(v));
332 }
333 _gc_cause = v;
334 }
335 GCCause::Cause gc_cause() { return _gc_cause; }
337 // Number of threads currently working on GC tasks.
338 uint n_par_threads() { return _n_par_threads; }
340 // May be overridden to set additional parallelism.
341 virtual void set_par_threads(uint t) { _n_par_threads = t; };
343 // Preload classes into the shared portion of the heap, and then dump
344 // that data to a file so that it can be loaded directly by another
345 // VM (then terminate).
346 virtual void preload_and_dump(TRAPS) { ShouldNotReachHere(); }
348 // Allocate and initialize instances of Class
349 static oop Class_obj_allocate(KlassHandle klass, int size, KlassHandle real_klass, TRAPS);
351 // General obj/array allocation facilities.
352 inline static oop obj_allocate(KlassHandle klass, int size, TRAPS);
353 inline static oop array_allocate(KlassHandle klass, int size, int length, TRAPS);
354 inline static oop array_allocate_nozero(KlassHandle klass, int size, int length, TRAPS);
356 // Special obj/array allocation facilities.
357 // Some heaps may want to manage "permanent" data uniquely. These default
358 // to the general routines if the heap does not support such handling.
359 inline static oop permanent_obj_allocate(KlassHandle klass, int size, TRAPS);
360 // permanent_obj_allocate_no_klass_install() does not do the installation of
361 // the klass pointer in the newly created object (as permanent_obj_allocate()
362 // above does). This allows for a delay in the installation of the klass
363 // pointer that is needed during the create of klassKlass's. The
364 // method post_allocation_install_obj_klass() is used to install the
365 // klass pointer.
366 inline static oop permanent_obj_allocate_no_klass_install(KlassHandle klass,
367 int size,
368 TRAPS);
369 inline static void post_allocation_install_obj_klass(KlassHandle klass,
370 oop obj,
371 int size);
372 inline static oop permanent_array_allocate(KlassHandle klass, int size, int length, TRAPS);
374 // Raw memory allocation facilities
375 // The obj and array allocate methods are covers for these methods.
376 // The permanent allocation method should default to mem_allocate if
377 // permanent memory isn't supported. mem_allocate() should never be
378 // called to allocate TLABs, only individual objects.
379 virtual HeapWord* mem_allocate(size_t size,
380 bool* gc_overhead_limit_was_exceeded) = 0;
381 virtual HeapWord* permanent_mem_allocate(size_t size) = 0;
383 // Utilities for turning raw memory into filler objects.
384 //
385 // min_fill_size() is the smallest region that can be filled.
386 // fill_with_objects() can fill arbitrary-sized regions of the heap using
387 // multiple objects. fill_with_object() is for regions known to be smaller
388 // than the largest array of integers; it uses a single object to fill the
389 // region and has slightly less overhead.
390 static size_t min_fill_size() {
391 return size_t(align_object_size(oopDesc::header_size()));
392 }
394 static void fill_with_objects(HeapWord* start, size_t words, bool zap = true);
396 static void fill_with_object(HeapWord* start, size_t words, bool zap = true);
397 static void fill_with_object(MemRegion region, bool zap = true) {
398 fill_with_object(region.start(), region.word_size(), zap);
399 }
400 static void fill_with_object(HeapWord* start, HeapWord* end, bool zap = true) {
401 fill_with_object(start, pointer_delta(end, start), zap);
402 }
404 // Some heaps may offer a contiguous region for shared non-blocking
405 // allocation, via inlined code (by exporting the address of the top and
406 // end fields defining the extent of the contiguous allocation region.)
408 // This function returns "true" iff the heap supports this kind of
409 // allocation. (Default is "no".)
410 virtual bool supports_inline_contig_alloc() const {
411 return false;
412 }
413 // These functions return the addresses of the fields that define the
414 // boundaries of the contiguous allocation area. (These fields should be
415 // physically near to one another.)
416 virtual HeapWord** top_addr() const {
417 guarantee(false, "inline contiguous allocation not supported");
418 return NULL;
419 }
420 virtual HeapWord** end_addr() const {
421 guarantee(false, "inline contiguous allocation not supported");
422 return NULL;
423 }
425 // Some heaps may be in an unparseable state at certain times between
426 // collections. This may be necessary for efficient implementation of
427 // certain allocation-related activities. Calling this function before
428 // attempting to parse a heap ensures that the heap is in a parsable
429 // state (provided other concurrent activity does not introduce
430 // unparsability). It is normally expected, therefore, that this
431 // method is invoked with the world stopped.
432 // NOTE: if you override this method, make sure you call
433 // super::ensure_parsability so that the non-generational
434 // part of the work gets done. See implementation of
435 // CollectedHeap::ensure_parsability and, for instance,
436 // that of GenCollectedHeap::ensure_parsability().
437 // The argument "retire_tlabs" controls whether existing TLABs
438 // are merely filled or also retired, thus preventing further
439 // allocation from them and necessitating allocation of new TLABs.
440 virtual void ensure_parsability(bool retire_tlabs);
442 // Return an estimate of the maximum allocation that could be performed
443 // without triggering any collection or expansion activity. In a
444 // generational collector, for example, this is probably the largest
445 // allocation that could be supported (without expansion) in the youngest
446 // generation. It is "unsafe" because no locks are taken; the result
447 // should be treated as an approximation, not a guarantee, for use in
448 // heuristic resizing decisions.
449 virtual size_t unsafe_max_alloc() = 0;
451 // Section on thread-local allocation buffers (TLABs)
452 // If the heap supports thread-local allocation buffers, it should override
453 // the following methods:
454 // Returns "true" iff the heap supports thread-local allocation buffers.
455 // The default is "no".
456 virtual bool supports_tlab_allocation() const {
457 return false;
458 }
459 // The amount of space available for thread-local allocation buffers.
460 virtual size_t tlab_capacity(Thread *thr) const {
461 guarantee(false, "thread-local allocation buffers not supported");
462 return 0;
463 }
464 // An estimate of the maximum allocation that could be performed
465 // for thread-local allocation buffers without triggering any
466 // collection or expansion activity.
467 virtual size_t unsafe_max_tlab_alloc(Thread *thr) const {
468 guarantee(false, "thread-local allocation buffers not supported");
469 return 0;
470 }
472 // Can a compiler initialize a new object without store barriers?
473 // This permission only extends from the creation of a new object
474 // via a TLAB up to the first subsequent safepoint. If such permission
475 // is granted for this heap type, the compiler promises to call
476 // defer_store_barrier() below on any slow path allocation of
477 // a new object for which such initializing store barriers will
478 // have been elided.
479 virtual bool can_elide_tlab_store_barriers() const = 0;
481 // If a compiler is eliding store barriers for TLAB-allocated objects,
482 // there is probably a corresponding slow path which can produce
483 // an object allocated anywhere. The compiler's runtime support
484 // promises to call this function on such a slow-path-allocated
485 // object before performing initializations that have elided
486 // store barriers. Returns new_obj, or maybe a safer copy thereof.
487 virtual oop new_store_pre_barrier(JavaThread* thread, oop new_obj);
489 // Answers whether an initializing store to a new object currently
490 // allocated at the given address doesn't need a store
491 // barrier. Returns "true" if it doesn't need an initializing
492 // store barrier; answers "false" if it does.
493 virtual bool can_elide_initializing_store_barrier(oop new_obj) = 0;
495 // If a compiler is eliding store barriers for TLAB-allocated objects,
496 // we will be informed of a slow-path allocation by a call
497 // to new_store_pre_barrier() above. Such a call precedes the
498 // initialization of the object itself, and no post-store-barriers will
499 // be issued. Some heap types require that the barrier strictly follows
500 // the initializing stores. (This is currently implemented by deferring the
501 // barrier until the next slow-path allocation or gc-related safepoint.)
502 // This interface answers whether a particular heap type needs the card
503 // mark to be thus strictly sequenced after the stores.
504 virtual bool card_mark_must_follow_store() const = 0;
506 // If the CollectedHeap was asked to defer a store barrier above,
507 // this informs it to flush such a deferred store barrier to the
508 // remembered set.
509 virtual void flush_deferred_store_barrier(JavaThread* thread);
511 // Can a compiler elide a store barrier when it writes
512 // a permanent oop into the heap? Applies when the compiler
513 // is storing x to the heap, where x->is_perm() is true.
514 virtual bool can_elide_permanent_oop_store_barriers() const = 0;
516 // Does this heap support heap inspection (+PrintClassHistogram?)
517 virtual bool supports_heap_inspection() const = 0;
519 // Perform a collection of the heap; intended for use in implementing
520 // "System.gc". This probably implies as full a collection as the
521 // "CollectedHeap" supports.
522 virtual void collect(GCCause::Cause cause) = 0;
524 // This interface assumes that it's being called by the
525 // vm thread. It collects the heap assuming that the
526 // heap lock is already held and that we are executing in
527 // the context of the vm thread.
528 virtual void collect_as_vm_thread(GCCause::Cause cause) = 0;
530 // Returns the barrier set for this heap
531 BarrierSet* barrier_set() { return _barrier_set; }
533 // Returns "true" iff there is a stop-world GC in progress. (I assume
534 // that it should answer "false" for the concurrent part of a concurrent
535 // collector -- dld).
536 bool is_gc_active() const { return _is_gc_active; }
538 // Total number of GC collections (started)
539 unsigned int total_collections() const { return _total_collections; }
540 unsigned int total_full_collections() const { return _total_full_collections;}
542 // Increment total number of GC collections (started)
543 // Should be protected but used by PSMarkSweep - cleanup for 1.4.2
544 void increment_total_collections(bool full = false) {
545 _total_collections++;
546 if (full) {
547 increment_total_full_collections();
548 }
549 }
551 void increment_total_full_collections() { _total_full_collections++; }
553 // Return the AdaptiveSizePolicy for the heap.
554 virtual AdaptiveSizePolicy* size_policy() = 0;
556 // Return the CollectorPolicy for the heap
557 virtual CollectorPolicy* collector_policy() const = 0;
559 // Iterate over all the ref-containing fields of all objects, calling
560 // "cl.do_oop" on each. This includes objects in permanent memory.
561 virtual void oop_iterate(OopClosure* cl) = 0;
563 // Iterate over all objects, calling "cl.do_object" on each.
564 // This includes objects in permanent memory.
565 virtual void object_iterate(ObjectClosure* cl) = 0;
567 // Similar to object_iterate() except iterates only
568 // over live objects.
569 virtual void safe_object_iterate(ObjectClosure* cl) = 0;
571 // Behaves the same as oop_iterate, except only traverses
572 // interior pointers contained in permanent memory. If there
573 // is no permanent memory, does nothing.
574 virtual void permanent_oop_iterate(OopClosure* cl) = 0;
576 // Behaves the same as object_iterate, except only traverses
577 // object contained in permanent memory. If there is no
578 // permanent memory, does nothing.
579 virtual void permanent_object_iterate(ObjectClosure* cl) = 0;
581 // NOTE! There is no requirement that a collector implement these
582 // functions.
583 //
584 // A CollectedHeap is divided into a dense sequence of "blocks"; that is,
585 // each address in the (reserved) heap is a member of exactly
586 // one block. The defining characteristic of a block is that it is
587 // possible to find its size, and thus to progress forward to the next
588 // block. (Blocks may be of different sizes.) Thus, blocks may
589 // represent Java objects, or they might be free blocks in a
590 // free-list-based heap (or subheap), as long as the two kinds are
591 // distinguishable and the size of each is determinable.
593 // Returns the address of the start of the "block" that contains the
594 // address "addr". We say "blocks" instead of "object" since some heaps
595 // may not pack objects densely; a chunk may either be an object or a
596 // non-object.
597 virtual HeapWord* block_start(const void* addr) const = 0;
599 // Requires "addr" to be the start of a chunk, and returns its size.
600 // "addr + size" is required to be the start of a new chunk, or the end
601 // of the active area of the heap.
602 virtual size_t block_size(const HeapWord* addr) const = 0;
604 // Requires "addr" to be the start of a block, and returns "TRUE" iff
605 // the block is an object.
606 virtual bool block_is_obj(const HeapWord* addr) const = 0;
608 // Returns the longest time (in ms) that has elapsed since the last
609 // time that any part of the heap was examined by a garbage collection.
610 virtual jlong millis_since_last_gc() = 0;
612 // Perform any cleanup actions necessary before allowing a verification.
613 virtual void prepare_for_verify() = 0;
615 // Generate any dumps preceding or following a full gc
616 void pre_full_gc_dump();
617 void post_full_gc_dump();
619 // Print heap information on the given outputStream.
620 virtual void print_on(outputStream* st) const = 0;
621 // The default behavior is to call print_on() on tty.
622 virtual void print() const {
623 print_on(tty);
624 }
625 // Print more detailed heap information on the given
626 // outputStream. The default behaviour is to call print_on(). It is
627 // up to each subclass to override it and add any additional output
628 // it needs.
629 virtual void print_extended_on(outputStream* st) const {
630 print_on(st);
631 }
633 // Print all GC threads (other than the VM thread)
634 // used by this heap.
635 virtual void print_gc_threads_on(outputStream* st) const = 0;
636 // The default behavior is to call print_gc_threads_on() on tty.
637 void print_gc_threads() {
638 print_gc_threads_on(tty);
639 }
640 // Iterator for all GC threads (other than VM thread)
641 virtual void gc_threads_do(ThreadClosure* tc) const = 0;
643 // Print any relevant tracing info that flags imply.
644 // Default implementation does nothing.
645 virtual void print_tracing_info() const = 0;
647 // If PrintHeapAtGC is set call the appropriate routi
648 void print_heap_before_gc() {
649 if (PrintHeapAtGC) {
650 Universe::print_heap_before_gc();
651 }
652 if (_gc_heap_log != NULL) {
653 _gc_heap_log->log_heap_before();
654 }
655 }
656 void print_heap_after_gc() {
657 if (PrintHeapAtGC) {
658 Universe::print_heap_after_gc();
659 }
660 if (_gc_heap_log != NULL) {
661 _gc_heap_log->log_heap_after();
662 }
663 }
665 // Allocate GCHeapLog during VM startup
666 static void initialize_heap_log();
668 // Heap verification
669 virtual void verify(bool allow_dirty, bool silent, VerifyOption option) = 0;
671 // Non product verification and debugging.
672 #ifndef PRODUCT
673 // Support for PromotionFailureALot. Return true if it's time to cause a
674 // promotion failure. The no-argument version uses
675 // this->_promotion_failure_alot_count as the counter.
676 inline bool promotion_should_fail(volatile size_t* count);
677 inline bool promotion_should_fail();
679 // Reset the PromotionFailureALot counters. Should be called at the end of a
680 // GC in which promotion failure ocurred.
681 inline void reset_promotion_should_fail(volatile size_t* count);
682 inline void reset_promotion_should_fail();
683 #endif // #ifndef PRODUCT
685 #ifdef ASSERT
686 static int fired_fake_oom() {
687 return (CIFireOOMAt > 1 && _fire_out_of_memory_count >= CIFireOOMAt);
688 }
689 #endif
691 public:
692 // This is a convenience method that is used in cases where
693 // the actual number of GC worker threads is not pertinent but
694 // only whether there more than 0. Use of this method helps
695 // reduce the occurrence of ParallelGCThreads to uses where the
696 // actual number may be germane.
697 static bool use_parallel_gc_threads() { return ParallelGCThreads > 0; }
699 /////////////// Unit tests ///////////////
701 NOT_PRODUCT(static void test_is_in();)
702 };
704 // Class to set and reset the GC cause for a CollectedHeap.
706 class GCCauseSetter : StackObj {
707 CollectedHeap* _heap;
708 GCCause::Cause _previous_cause;
709 public:
710 GCCauseSetter(CollectedHeap* heap, GCCause::Cause cause) {
711 assert(SafepointSynchronize::is_at_safepoint(),
712 "This method manipulates heap state without locking");
713 _heap = heap;
714 _previous_cause = _heap->gc_cause();
715 _heap->set_gc_cause(cause);
716 }
718 ~GCCauseSetter() {
719 assert(SafepointSynchronize::is_at_safepoint(),
720 "This method manipulates heap state without locking");
721 _heap->set_gc_cause(_previous_cause);
722 }
723 };
725 #endif // SHARE_VM_GC_INTERFACE_COLLECTEDHEAP_HPP