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 #include "precompiled.hpp"
26 #include "classfile/systemDictionary.hpp"
27 #include "gc_implementation/shared/vmGCOperations.hpp"
28 #include "gc_interface/collectedHeap.hpp"
29 #include "gc_interface/collectedHeap.inline.hpp"
30 #include "oops/oop.inline.hpp"
31 #include "oops/instanceMirrorKlass.hpp"
32 #include "runtime/init.hpp"
33 #include "services/heapDumper.hpp"
34 #ifdef TARGET_OS_FAMILY_linux
35 # include "thread_linux.inline.hpp"
36 #endif
37 #ifdef TARGET_OS_FAMILY_solaris
38 # include "thread_solaris.inline.hpp"
39 #endif
40 #ifdef TARGET_OS_FAMILY_windows
41 # include "thread_windows.inline.hpp"
42 #endif
43 #ifdef TARGET_OS_FAMILY_bsd
44 # include "thread_bsd.inline.hpp"
45 #endif
48 #ifdef ASSERT
49 int CollectedHeap::_fire_out_of_memory_count = 0;
50 #endif
52 size_t CollectedHeap::_filler_array_max_size = 0;
54 template <>
55 void EventLogBase<GCMessage>::print(outputStream* st, GCMessage& m) {
56 st->print_cr("GC heap %s", m.is_before ? "before" : "after");
57 st->print_raw(m);
58 }
60 void GCHeapLog::log_heap(bool before) {
61 if (!should_log()) {
62 return;
63 }
65 jlong timestamp = os::javaTimeNanos() / NANOSECS_PER_MILLISEC;
66 MutexLockerEx ml(&_mutex, Mutex::_no_safepoint_check_flag);
67 int index = compute_log_index();
68 _records[index].thread = NULL; // Its the GC thread so it's not that interesting.
69 _records[index].timestamp = timestamp;
70 _records[index].data.is_before = before;
71 stringStream st(_records[index].data.buffer(), _records[index].data.size());
72 if (before) {
73 Universe::print_heap_before_gc(&st);
74 } else {
75 Universe::print_heap_after_gc(&st);
76 }
77 }
79 // Memory state functions.
82 CollectedHeap::CollectedHeap() : _n_par_threads(0)
84 {
85 const size_t max_len = size_t(arrayOopDesc::max_array_length(T_INT));
86 const size_t elements_per_word = HeapWordSize / sizeof(jint);
87 _filler_array_max_size = align_object_size(filler_array_hdr_size() +
88 max_len * elements_per_word);
90 _barrier_set = NULL;
91 _is_gc_active = false;
92 _total_collections = _total_full_collections = 0;
93 _gc_cause = _gc_lastcause = GCCause::_no_gc;
94 NOT_PRODUCT(_promotion_failure_alot_count = 0;)
95 NOT_PRODUCT(_promotion_failure_alot_gc_number = 0;)
97 if (UsePerfData) {
98 EXCEPTION_MARK;
100 // create the gc cause jvmstat counters
101 _perf_gc_cause = PerfDataManager::create_string_variable(SUN_GC, "cause",
102 80, GCCause::to_string(_gc_cause), CHECK);
104 _perf_gc_lastcause =
105 PerfDataManager::create_string_variable(SUN_GC, "lastCause",
106 80, GCCause::to_string(_gc_lastcause), CHECK);
107 }
108 _defer_initial_card_mark = false; // strengthened by subclass in pre_initialize() below.
109 // Create the ring log
110 if (LogEvents) {
111 _gc_heap_log = new GCHeapLog();
112 } else {
113 _gc_heap_log = NULL;
114 }
115 }
117 void CollectedHeap::pre_initialize() {
118 // Used for ReduceInitialCardMarks (when COMPILER2 is used);
119 // otherwise remains unused.
120 #ifdef COMPILER2
121 _defer_initial_card_mark = ReduceInitialCardMarks && can_elide_tlab_store_barriers()
122 && (DeferInitialCardMark || card_mark_must_follow_store());
123 #else
124 assert(_defer_initial_card_mark == false, "Who would set it?");
125 #endif
126 }
128 #ifndef PRODUCT
129 void CollectedHeap::check_for_bad_heap_word_value(HeapWord* addr, size_t size) {
130 if (CheckMemoryInitialization && ZapUnusedHeapArea) {
131 for (size_t slot = 0; slot < size; slot += 1) {
132 assert((*(intptr_t*) (addr + slot)) != ((intptr_t) badHeapWordVal),
133 "Found badHeapWordValue in post-allocation check");
134 }
135 }
136 }
138 void CollectedHeap::check_for_non_bad_heap_word_value(HeapWord* addr, size_t size) {
139 if (CheckMemoryInitialization && ZapUnusedHeapArea) {
140 for (size_t slot = 0; slot < size; slot += 1) {
141 assert((*(intptr_t*) (addr + slot)) == ((intptr_t) badHeapWordVal),
142 "Found non badHeapWordValue in pre-allocation check");
143 }
144 }
145 }
146 #endif // PRODUCT
148 #ifdef ASSERT
149 void CollectedHeap::check_for_valid_allocation_state() {
150 Thread *thread = Thread::current();
151 // How to choose between a pending exception and a potential
152 // OutOfMemoryError? Don't allow pending exceptions.
153 // This is a VM policy failure, so how do we exhaustively test it?
154 assert(!thread->has_pending_exception(),
155 "shouldn't be allocating with pending exception");
156 if (StrictSafepointChecks) {
157 assert(thread->allow_allocation(),
158 "Allocation done by thread for which allocation is blocked "
159 "by No_Allocation_Verifier!");
160 // Allocation of an oop can always invoke a safepoint,
161 // hence, the true argument
162 thread->check_for_valid_safepoint_state(true);
163 }
164 }
165 #endif
167 HeapWord* CollectedHeap::allocate_from_tlab_slow(Thread* thread, size_t size) {
169 // Retain tlab and allocate object in shared space if
170 // the amount free in the tlab is too large to discard.
171 if (thread->tlab().free() > thread->tlab().refill_waste_limit()) {
172 thread->tlab().record_slow_allocation(size);
173 return NULL;
174 }
176 // Discard tlab and allocate a new one.
177 // To minimize fragmentation, the last TLAB may be smaller than the rest.
178 size_t new_tlab_size = thread->tlab().compute_size(size);
180 thread->tlab().clear_before_allocation();
182 if (new_tlab_size == 0) {
183 return NULL;
184 }
186 // Allocate a new TLAB...
187 HeapWord* obj = Universe::heap()->allocate_new_tlab(new_tlab_size);
188 if (obj == NULL) {
189 return NULL;
190 }
191 if (ZeroTLAB) {
192 // ..and clear it.
193 Copy::zero_to_words(obj, new_tlab_size);
194 } else {
195 // ...and zap just allocated object.
196 #ifdef ASSERT
197 // Skip mangling the space corresponding to the object header to
198 // ensure that the returned space is not considered parsable by
199 // any concurrent GC thread.
200 size_t hdr_size = oopDesc::header_size();
201 Copy::fill_to_words(obj + hdr_size, new_tlab_size - hdr_size, badHeapWordVal);
202 #endif // ASSERT
203 }
204 thread->tlab().fill(obj, obj + size, new_tlab_size);
205 return obj;
206 }
208 void CollectedHeap::flush_deferred_store_barrier(JavaThread* thread) {
209 MemRegion deferred = thread->deferred_card_mark();
210 if (!deferred.is_empty()) {
211 assert(_defer_initial_card_mark, "Otherwise should be empty");
212 {
213 // Verify that the storage points to a parsable object in heap
214 DEBUG_ONLY(oop old_obj = oop(deferred.start());)
215 assert(is_in(old_obj), "Not in allocated heap");
216 assert(!can_elide_initializing_store_barrier(old_obj),
217 "Else should have been filtered in new_store_pre_barrier()");
218 assert(!is_in_permanent(old_obj), "Sanity: not expected");
219 assert(old_obj->is_oop(true), "Not an oop");
220 assert(old_obj->is_parsable(), "Will not be concurrently parsable");
221 assert(deferred.word_size() == (size_t)(old_obj->size()),
222 "Mismatch: multiple objects?");
223 }
224 BarrierSet* bs = barrier_set();
225 assert(bs->has_write_region_opt(), "No write_region() on BarrierSet");
226 bs->write_region(deferred);
227 // "Clear" the deferred_card_mark field
228 thread->set_deferred_card_mark(MemRegion());
229 }
230 assert(thread->deferred_card_mark().is_empty(), "invariant");
231 }
233 // Helper for ReduceInitialCardMarks. For performance,
234 // compiled code may elide card-marks for initializing stores
235 // to a newly allocated object along the fast-path. We
236 // compensate for such elided card-marks as follows:
237 // (a) Generational, non-concurrent collectors, such as
238 // GenCollectedHeap(ParNew,DefNew,Tenured) and
239 // ParallelScavengeHeap(ParallelGC, ParallelOldGC)
240 // need the card-mark if and only if the region is
241 // in the old gen, and do not care if the card-mark
242 // succeeds or precedes the initializing stores themselves,
243 // so long as the card-mark is completed before the next
244 // scavenge. For all these cases, we can do a card mark
245 // at the point at which we do a slow path allocation
246 // in the old gen, i.e. in this call.
247 // (b) GenCollectedHeap(ConcurrentMarkSweepGeneration) requires
248 // in addition that the card-mark for an old gen allocated
249 // object strictly follow any associated initializing stores.
250 // In these cases, the memRegion remembered below is
251 // used to card-mark the entire region either just before the next
252 // slow-path allocation by this thread or just before the next scavenge or
253 // CMS-associated safepoint, whichever of these events happens first.
254 // (The implicit assumption is that the object has been fully
255 // initialized by this point, a fact that we assert when doing the
256 // card-mark.)
257 // (c) G1CollectedHeap(G1) uses two kinds of write barriers. When a
258 // G1 concurrent marking is in progress an SATB (pre-write-)barrier is
259 // is used to remember the pre-value of any store. Initializing
260 // stores will not need this barrier, so we need not worry about
261 // compensating for the missing pre-barrier here. Turning now
262 // to the post-barrier, we note that G1 needs a RS update barrier
263 // which simply enqueues a (sequence of) dirty cards which may
264 // optionally be refined by the concurrent update threads. Note
265 // that this barrier need only be applied to a non-young write,
266 // but, like in CMS, because of the presence of concurrent refinement
267 // (much like CMS' precleaning), must strictly follow the oop-store.
268 // Thus, using the same protocol for maintaining the intended
269 // invariants turns out, serendepitously, to be the same for both
270 // G1 and CMS.
271 //
272 // For any future collector, this code should be reexamined with
273 // that specific collector in mind, and the documentation above suitably
274 // extended and updated.
275 oop CollectedHeap::new_store_pre_barrier(JavaThread* thread, oop new_obj) {
276 // If a previous card-mark was deferred, flush it now.
277 flush_deferred_store_barrier(thread);
278 if (can_elide_initializing_store_barrier(new_obj)) {
279 // The deferred_card_mark region should be empty
280 // following the flush above.
281 assert(thread->deferred_card_mark().is_empty(), "Error");
282 } else {
283 MemRegion mr((HeapWord*)new_obj, new_obj->size());
284 assert(!mr.is_empty(), "Error");
285 if (_defer_initial_card_mark) {
286 // Defer the card mark
287 thread->set_deferred_card_mark(mr);
288 } else {
289 // Do the card mark
290 BarrierSet* bs = barrier_set();
291 assert(bs->has_write_region_opt(), "No write_region() on BarrierSet");
292 bs->write_region(mr);
293 }
294 }
295 return new_obj;
296 }
298 size_t CollectedHeap::filler_array_hdr_size() {
299 return size_t(align_object_offset(arrayOopDesc::header_size(T_INT))); // align to Long
300 }
302 size_t CollectedHeap::filler_array_min_size() {
303 return align_object_size(filler_array_hdr_size()); // align to MinObjAlignment
304 }
306 size_t CollectedHeap::filler_array_max_size() {
307 return _filler_array_max_size;
308 }
310 #ifdef ASSERT
311 void CollectedHeap::fill_args_check(HeapWord* start, size_t words)
312 {
313 assert(words >= min_fill_size(), "too small to fill");
314 assert(words % MinObjAlignment == 0, "unaligned size");
315 assert(Universe::heap()->is_in_reserved(start), "not in heap");
316 assert(Universe::heap()->is_in_reserved(start + words - 1), "not in heap");
317 }
319 void CollectedHeap::zap_filler_array(HeapWord* start, size_t words, bool zap)
320 {
321 if (ZapFillerObjects && zap) {
322 Copy::fill_to_words(start + filler_array_hdr_size(),
323 words - filler_array_hdr_size(), 0XDEAFBABE);
324 }
325 }
326 #endif // ASSERT
328 void
329 CollectedHeap::fill_with_array(HeapWord* start, size_t words, bool zap)
330 {
331 assert(words >= filler_array_min_size(), "too small for an array");
332 assert(words <= filler_array_max_size(), "too big for a single object");
334 const size_t payload_size = words - filler_array_hdr_size();
335 const size_t len = payload_size * HeapWordSize / sizeof(jint);
337 // Set the length first for concurrent GC.
338 ((arrayOop)start)->set_length((int)len);
339 post_allocation_setup_common(Universe::intArrayKlassObj(), start, words);
340 DEBUG_ONLY(zap_filler_array(start, words, zap);)
341 }
343 void
344 CollectedHeap::fill_with_object_impl(HeapWord* start, size_t words, bool zap)
345 {
346 assert(words <= filler_array_max_size(), "too big for a single object");
348 if (words >= filler_array_min_size()) {
349 fill_with_array(start, words, zap);
350 } else if (words > 0) {
351 assert(words == min_fill_size(), "unaligned size");
352 post_allocation_setup_common(SystemDictionary::Object_klass(), start,
353 words);
354 }
355 }
357 void CollectedHeap::fill_with_object(HeapWord* start, size_t words, bool zap)
358 {
359 DEBUG_ONLY(fill_args_check(start, words);)
360 HandleMark hm; // Free handles before leaving.
361 fill_with_object_impl(start, words, zap);
362 }
364 void CollectedHeap::fill_with_objects(HeapWord* start, size_t words, bool zap)
365 {
366 DEBUG_ONLY(fill_args_check(start, words);)
367 HandleMark hm; // Free handles before leaving.
369 #ifdef _LP64
370 // A single array can fill ~8G, so multiple objects are needed only in 64-bit.
371 // First fill with arrays, ensuring that any remaining space is big enough to
372 // fill. The remainder is filled with a single object.
373 const size_t min = min_fill_size();
374 const size_t max = filler_array_max_size();
375 while (words > max) {
376 const size_t cur = words - max >= min ? max : max - min;
377 fill_with_array(start, cur, zap);
378 start += cur;
379 words -= cur;
380 }
381 #endif
383 fill_with_object_impl(start, words, zap);
384 }
386 HeapWord* CollectedHeap::allocate_new_tlab(size_t size) {
387 guarantee(false, "thread-local allocation buffers not supported");
388 return NULL;
389 }
391 void CollectedHeap::ensure_parsability(bool retire_tlabs) {
392 // The second disjunct in the assertion below makes a concession
393 // for the start-up verification done while the VM is being
394 // created. Callers be careful that you know that mutators
395 // aren't going to interfere -- for instance, this is permissible
396 // if we are still single-threaded and have either not yet
397 // started allocating (nothing much to verify) or we have
398 // started allocating but are now a full-fledged JavaThread
399 // (and have thus made our TLAB's) available for filling.
400 assert(SafepointSynchronize::is_at_safepoint() ||
401 !is_init_completed(),
402 "Should only be called at a safepoint or at start-up"
403 " otherwise concurrent mutator activity may make heap "
404 " unparsable again");
405 const bool use_tlab = UseTLAB;
406 const bool deferred = _defer_initial_card_mark;
407 // The main thread starts allocating via a TLAB even before it
408 // has added itself to the threads list at vm boot-up.
409 assert(!use_tlab || Threads::first() != NULL,
410 "Attempt to fill tlabs before main thread has been added"
411 " to threads list is doomed to failure!");
412 for (JavaThread *thread = Threads::first(); thread; thread = thread->next()) {
413 if (use_tlab) thread->tlab().make_parsable(retire_tlabs);
414 #ifdef COMPILER2
415 // The deferred store barriers must all have been flushed to the
416 // card-table (or other remembered set structure) before GC starts
417 // processing the card-table (or other remembered set).
418 if (deferred) flush_deferred_store_barrier(thread);
419 #else
420 assert(!deferred, "Should be false");
421 assert(thread->deferred_card_mark().is_empty(), "Should be empty");
422 #endif
423 }
424 }
426 void CollectedHeap::accumulate_statistics_all_tlabs() {
427 if (UseTLAB) {
428 assert(SafepointSynchronize::is_at_safepoint() ||
429 !is_init_completed(),
430 "should only accumulate statistics on tlabs at safepoint");
432 ThreadLocalAllocBuffer::accumulate_statistics_before_gc();
433 }
434 }
436 void CollectedHeap::resize_all_tlabs() {
437 if (UseTLAB) {
438 assert(SafepointSynchronize::is_at_safepoint() ||
439 !is_init_completed(),
440 "should only resize tlabs at safepoint");
442 ThreadLocalAllocBuffer::resize_all_tlabs();
443 }
444 }
446 void CollectedHeap::pre_full_gc_dump() {
447 if (HeapDumpBeforeFullGC) {
448 TraceTime tt("Heap Dump (before full gc): ", PrintGCDetails, false, gclog_or_tty);
449 // We are doing a "major" collection and a heap dump before
450 // major collection has been requested.
451 HeapDumper::dump_heap();
452 }
453 if (PrintClassHistogramBeforeFullGC) {
454 TraceTime tt("Class Histogram (before full gc): ", PrintGCDetails, true, gclog_or_tty);
455 VM_GC_HeapInspection inspector(gclog_or_tty, false /* ! full gc */, false /* ! prologue */);
456 inspector.doit();
457 }
458 }
460 void CollectedHeap::post_full_gc_dump() {
461 if (HeapDumpAfterFullGC) {
462 TraceTime tt("Heap Dump (after full gc): ", PrintGCDetails, false, gclog_or_tty);
463 HeapDumper::dump_heap();
464 }
465 if (PrintClassHistogramAfterFullGC) {
466 TraceTime tt("Class Histogram (after full gc): ", PrintGCDetails, true, gclog_or_tty);
467 VM_GC_HeapInspection inspector(gclog_or_tty, false /* ! full gc */, false /* ! prologue */);
468 inspector.doit();
469 }
470 }
472 oop CollectedHeap::Class_obj_allocate(KlassHandle klass, int size, KlassHandle real_klass, TRAPS) {
473 debug_only(check_for_valid_allocation_state());
474 assert(!Universe::heap()->is_gc_active(), "Allocation during gc not allowed");
475 assert(size >= 0, "int won't convert to size_t");
476 HeapWord* obj;
477 if (JavaObjectsInPerm) {
478 obj = common_permanent_mem_allocate_init(size, CHECK_NULL);
479 } else {
480 assert(ScavengeRootsInCode > 0, "must be");
481 obj = common_mem_allocate_init(size, CHECK_NULL);
482 }
483 post_allocation_setup_common(klass, obj, size);
484 assert(Universe::is_bootstrapping() ||
485 !((oop)obj)->blueprint()->oop_is_array(), "must not be an array");
486 NOT_PRODUCT(Universe::heap()->check_for_bad_heap_word_value(obj, size));
487 oop mirror = (oop)obj;
489 java_lang_Class::set_oop_size(mirror, size);
491 // Setup indirections
492 if (!real_klass.is_null()) {
493 java_lang_Class::set_klass(mirror, real_klass());
494 real_klass->set_java_mirror(mirror);
495 }
497 instanceMirrorKlass* mk = instanceMirrorKlass::cast(mirror->klass());
498 assert(size == mk->instance_size(real_klass), "should have been set");
500 // notify jvmti and dtrace
501 post_allocation_notify(klass, (oop)obj);
503 return mirror;
504 }
506 /////////////// Unit tests ///////////////
508 #ifndef PRODUCT
509 void CollectedHeap::test_is_in() {
510 CollectedHeap* heap = Universe::heap();
512 uintptr_t epsilon = (uintptr_t) MinObjAlignment;
513 uintptr_t heap_start = (uintptr_t) heap->_reserved.start();
514 uintptr_t heap_end = (uintptr_t) heap->_reserved.end();
516 // Test that NULL is not in the heap.
517 assert(!heap->is_in(NULL), "NULL is unexpectedly in the heap");
519 // Test that a pointer to before the heap start is reported as outside the heap.
520 assert(heap_start >= ((uintptr_t)NULL + epsilon), "sanity");
521 void* before_heap = (void*)(heap_start - epsilon);
522 assert(!heap->is_in(before_heap),
523 err_msg("before_heap: " PTR_FORMAT " is unexpectedly in the heap", before_heap));
525 // Test that a pointer to after the heap end is reported as outside the heap.
526 assert(heap_end <= ((uintptr_t)-1 - epsilon), "sanity");
527 void* after_heap = (void*)(heap_end + epsilon);
528 assert(!heap->is_in(after_heap),
529 err_msg("after_heap: " PTR_FORMAT " is unexpectedly in the heap", after_heap));
530 }
531 #endif