| /* |
| * Copyright (c) 2001, 2009, Oracle and/or its affiliates. All rights reserved. |
| * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
| * |
| * This code is free software; you can redistribute it and/or modify it |
| * under the terms of the GNU General Public License version 2 only, as |
| * published by the Free Software Foundation. |
| * |
| * This code is distributed in the hope that it will be useful, but WITHOUT |
| * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
| * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
| * version 2 for more details (a copy is included in the LICENSE file that |
| * accompanied this code). |
| * |
| * You should have received a copy of the GNU General Public License version |
| * 2 along with this work; if not, write to the Free Software Foundation, |
| * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
| * |
| * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
| * or visit www.oracle.com if you need additional information or have any |
| * questions. |
| * |
| */ |
| |
| # include "incls/_precompiled.incl" |
| # include "incls/_collectedHeap.cpp.incl" |
| |
| |
| #ifdef ASSERT |
| int CollectedHeap::_fire_out_of_memory_count = 0; |
| #endif |
| |
| size_t CollectedHeap::_filler_array_max_size = 0; |
| |
| // Memory state functions. |
| |
| CollectedHeap::CollectedHeap() |
| { |
| const size_t max_len = size_t(arrayOopDesc::max_array_length(T_INT)); |
| const size_t elements_per_word = HeapWordSize / sizeof(jint); |
| _filler_array_max_size = align_object_size(filler_array_hdr_size() + |
| max_len * elements_per_word); |
| |
| _barrier_set = NULL; |
| _is_gc_active = false; |
| _total_collections = _total_full_collections = 0; |
| _gc_cause = _gc_lastcause = GCCause::_no_gc; |
| NOT_PRODUCT(_promotion_failure_alot_count = 0;) |
| NOT_PRODUCT(_promotion_failure_alot_gc_number = 0;) |
| |
| if (UsePerfData) { |
| EXCEPTION_MARK; |
| |
| // create the gc cause jvmstat counters |
| _perf_gc_cause = PerfDataManager::create_string_variable(SUN_GC, "cause", |
| 80, GCCause::to_string(_gc_cause), CHECK); |
| |
| _perf_gc_lastcause = |
| PerfDataManager::create_string_variable(SUN_GC, "lastCause", |
| 80, GCCause::to_string(_gc_lastcause), CHECK); |
| } |
| _defer_initial_card_mark = false; // strengthened by subclass in pre_initialize() below. |
| } |
| |
| void CollectedHeap::pre_initialize() { |
| // Used for ReduceInitialCardMarks (when COMPILER2 is used); |
| // otherwise remains unused. |
| #ifdef COMPILER2 |
| _defer_initial_card_mark = ReduceInitialCardMarks && can_elide_tlab_store_barriers() |
| && (DeferInitialCardMark || card_mark_must_follow_store()); |
| #else |
| assert(_defer_initial_card_mark == false, "Who would set it?"); |
| #endif |
| } |
| |
| #ifndef PRODUCT |
| void CollectedHeap::check_for_bad_heap_word_value(HeapWord* addr, size_t size) { |
| if (CheckMemoryInitialization && ZapUnusedHeapArea) { |
| for (size_t slot = 0; slot < size; slot += 1) { |
| assert((*(intptr_t*) (addr + slot)) != ((intptr_t) badHeapWordVal), |
| "Found badHeapWordValue in post-allocation check"); |
| } |
| } |
| } |
| |
| void CollectedHeap::check_for_non_bad_heap_word_value(HeapWord* addr, size_t size) |
| { |
| if (CheckMemoryInitialization && ZapUnusedHeapArea) { |
| for (size_t slot = 0; slot < size; slot += 1) { |
| assert((*(intptr_t*) (addr + slot)) == ((intptr_t) badHeapWordVal), |
| "Found non badHeapWordValue in pre-allocation check"); |
| } |
| } |
| } |
| #endif // PRODUCT |
| |
| #ifdef ASSERT |
| void CollectedHeap::check_for_valid_allocation_state() { |
| Thread *thread = Thread::current(); |
| // How to choose between a pending exception and a potential |
| // OutOfMemoryError? Don't allow pending exceptions. |
| // This is a VM policy failure, so how do we exhaustively test it? |
| assert(!thread->has_pending_exception(), |
| "shouldn't be allocating with pending exception"); |
| if (StrictSafepointChecks) { |
| assert(thread->allow_allocation(), |
| "Allocation done by thread for which allocation is blocked " |
| "by No_Allocation_Verifier!"); |
| // Allocation of an oop can always invoke a safepoint, |
| // hence, the true argument |
| thread->check_for_valid_safepoint_state(true); |
| } |
| } |
| #endif |
| |
| HeapWord* CollectedHeap::allocate_from_tlab_slow(Thread* thread, size_t size) { |
| |
| // Retain tlab and allocate object in shared space if |
| // the amount free in the tlab is too large to discard. |
| if (thread->tlab().free() > thread->tlab().refill_waste_limit()) { |
| thread->tlab().record_slow_allocation(size); |
| return NULL; |
| } |
| |
| // Discard tlab and allocate a new one. |
| // To minimize fragmentation, the last TLAB may be smaller than the rest. |
| size_t new_tlab_size = thread->tlab().compute_size(size); |
| |
| thread->tlab().clear_before_allocation(); |
| |
| if (new_tlab_size == 0) { |
| return NULL; |
| } |
| |
| // Allocate a new TLAB... |
| HeapWord* obj = Universe::heap()->allocate_new_tlab(new_tlab_size); |
| if (obj == NULL) { |
| return NULL; |
| } |
| if (ZeroTLAB) { |
| // ..and clear it. |
| Copy::zero_to_words(obj, new_tlab_size); |
| } else { |
| // ...and clear just the allocated object. |
| Copy::zero_to_words(obj, size); |
| } |
| thread->tlab().fill(obj, obj + size, new_tlab_size); |
| return obj; |
| } |
| |
| void CollectedHeap::flush_deferred_store_barrier(JavaThread* thread) { |
| MemRegion deferred = thread->deferred_card_mark(); |
| if (!deferred.is_empty()) { |
| assert(_defer_initial_card_mark, "Otherwise should be empty"); |
| { |
| // Verify that the storage points to a parsable object in heap |
| DEBUG_ONLY(oop old_obj = oop(deferred.start());) |
| assert(is_in(old_obj), "Not in allocated heap"); |
| assert(!can_elide_initializing_store_barrier(old_obj), |
| "Else should have been filtered in new_store_pre_barrier()"); |
| assert(!is_in_permanent(old_obj), "Sanity: not expected"); |
| assert(old_obj->is_oop(true), "Not an oop"); |
| assert(old_obj->is_parsable(), "Will not be concurrently parsable"); |
| assert(deferred.word_size() == (size_t)(old_obj->size()), |
| "Mismatch: multiple objects?"); |
| } |
| BarrierSet* bs = barrier_set(); |
| assert(bs->has_write_region_opt(), "No write_region() on BarrierSet"); |
| bs->write_region(deferred); |
| // "Clear" the deferred_card_mark field |
| thread->set_deferred_card_mark(MemRegion()); |
| } |
| assert(thread->deferred_card_mark().is_empty(), "invariant"); |
| } |
| |
| // Helper for ReduceInitialCardMarks. For performance, |
| // compiled code may elide card-marks for initializing stores |
| // to a newly allocated object along the fast-path. We |
| // compensate for such elided card-marks as follows: |
| // (a) Generational, non-concurrent collectors, such as |
| // GenCollectedHeap(ParNew,DefNew,Tenured) and |
| // ParallelScavengeHeap(ParallelGC, ParallelOldGC) |
| // need the card-mark if and only if the region is |
| // in the old gen, and do not care if the card-mark |
| // succeeds or precedes the initializing stores themselves, |
| // so long as the card-mark is completed before the next |
| // scavenge. For all these cases, we can do a card mark |
| // at the point at which we do a slow path allocation |
| // in the old gen, i.e. in this call. |
| // (b) GenCollectedHeap(ConcurrentMarkSweepGeneration) requires |
| // in addition that the card-mark for an old gen allocated |
| // object strictly follow any associated initializing stores. |
| // In these cases, the memRegion remembered below is |
| // used to card-mark the entire region either just before the next |
| // slow-path allocation by this thread or just before the next scavenge or |
| // CMS-associated safepoint, whichever of these events happens first. |
| // (The implicit assumption is that the object has been fully |
| // initialized by this point, a fact that we assert when doing the |
| // card-mark.) |
| // (c) G1CollectedHeap(G1) uses two kinds of write barriers. When a |
| // G1 concurrent marking is in progress an SATB (pre-write-)barrier is |
| // is used to remember the pre-value of any store. Initializing |
| // stores will not need this barrier, so we need not worry about |
| // compensating for the missing pre-barrier here. Turning now |
| // to the post-barrier, we note that G1 needs a RS update barrier |
| // which simply enqueues a (sequence of) dirty cards which may |
| // optionally be refined by the concurrent update threads. Note |
| // that this barrier need only be applied to a non-young write, |
| // but, like in CMS, because of the presence of concurrent refinement |
| // (much like CMS' precleaning), must strictly follow the oop-store. |
| // Thus, using the same protocol for maintaining the intended |
| // invariants turns out, serendepitously, to be the same for both |
| // G1 and CMS. |
| // |
| // For any future collector, this code should be reexamined with |
| // that specific collector in mind, and the documentation above suitably |
| // extended and updated. |
| oop CollectedHeap::new_store_pre_barrier(JavaThread* thread, oop new_obj) { |
| // If a previous card-mark was deferred, flush it now. |
| flush_deferred_store_barrier(thread); |
| if (can_elide_initializing_store_barrier(new_obj)) { |
| // The deferred_card_mark region should be empty |
| // following the flush above. |
| assert(thread->deferred_card_mark().is_empty(), "Error"); |
| } else { |
| MemRegion mr((HeapWord*)new_obj, new_obj->size()); |
| assert(!mr.is_empty(), "Error"); |
| if (_defer_initial_card_mark) { |
| // Defer the card mark |
| thread->set_deferred_card_mark(mr); |
| } else { |
| // Do the card mark |
| BarrierSet* bs = barrier_set(); |
| assert(bs->has_write_region_opt(), "No write_region() on BarrierSet"); |
| bs->write_region(mr); |
| } |
| } |
| return new_obj; |
| } |
| |
| size_t CollectedHeap::filler_array_hdr_size() { |
| return size_t(align_object_offset(arrayOopDesc::header_size(T_INT))); // align to Long |
| } |
| |
| size_t CollectedHeap::filler_array_min_size() { |
| return align_object_size(filler_array_hdr_size()); // align to MinObjAlignment |
| } |
| |
| size_t CollectedHeap::filler_array_max_size() { |
| return _filler_array_max_size; |
| } |
| |
| #ifdef ASSERT |
| void CollectedHeap::fill_args_check(HeapWord* start, size_t words) |
| { |
| assert(words >= min_fill_size(), "too small to fill"); |
| assert(words % MinObjAlignment == 0, "unaligned size"); |
| assert(Universe::heap()->is_in_reserved(start), "not in heap"); |
| assert(Universe::heap()->is_in_reserved(start + words - 1), "not in heap"); |
| } |
| |
| void CollectedHeap::zap_filler_array(HeapWord* start, size_t words, bool zap) |
| { |
| if (ZapFillerObjects && zap) { |
| Copy::fill_to_words(start + filler_array_hdr_size(), |
| words - filler_array_hdr_size(), 0XDEAFBABE); |
| } |
| } |
| #endif // ASSERT |
| |
| void |
| CollectedHeap::fill_with_array(HeapWord* start, size_t words, bool zap) |
| { |
| assert(words >= filler_array_min_size(), "too small for an array"); |
| assert(words <= filler_array_max_size(), "too big for a single object"); |
| |
| const size_t payload_size = words - filler_array_hdr_size(); |
| const size_t len = payload_size * HeapWordSize / sizeof(jint); |
| |
| // Set the length first for concurrent GC. |
| ((arrayOop)start)->set_length((int)len); |
| post_allocation_setup_common(Universe::intArrayKlassObj(), start, words); |
| DEBUG_ONLY(zap_filler_array(start, words, zap);) |
| } |
| |
| void |
| CollectedHeap::fill_with_object_impl(HeapWord* start, size_t words, bool zap) |
| { |
| assert(words <= filler_array_max_size(), "too big for a single object"); |
| |
| if (words >= filler_array_min_size()) { |
| fill_with_array(start, words, zap); |
| } else if (words > 0) { |
| assert(words == min_fill_size(), "unaligned size"); |
| post_allocation_setup_common(SystemDictionary::Object_klass(), start, |
| words); |
| } |
| } |
| |
| void CollectedHeap::fill_with_object(HeapWord* start, size_t words, bool zap) |
| { |
| DEBUG_ONLY(fill_args_check(start, words);) |
| HandleMark hm; // Free handles before leaving. |
| fill_with_object_impl(start, words, zap); |
| } |
| |
| void CollectedHeap::fill_with_objects(HeapWord* start, size_t words, bool zap) |
| { |
| DEBUG_ONLY(fill_args_check(start, words);) |
| HandleMark hm; // Free handles before leaving. |
| |
| #ifdef _LP64 |
| // A single array can fill ~8G, so multiple objects are needed only in 64-bit. |
| // First fill with arrays, ensuring that any remaining space is big enough to |
| // fill. The remainder is filled with a single object. |
| const size_t min = min_fill_size(); |
| const size_t max = filler_array_max_size(); |
| while (words > max) { |
| const size_t cur = words - max >= min ? max : max - min; |
| fill_with_array(start, cur, zap); |
| start += cur; |
| words -= cur; |
| } |
| #endif |
| |
| fill_with_object_impl(start, words, zap); |
| } |
| |
| HeapWord* CollectedHeap::allocate_new_tlab(size_t size) { |
| guarantee(false, "thread-local allocation buffers not supported"); |
| return NULL; |
| } |
| |
| void CollectedHeap::ensure_parsability(bool retire_tlabs) { |
| // The second disjunct in the assertion below makes a concession |
| // for the start-up verification done while the VM is being |
| // created. Callers be careful that you know that mutators |
| // aren't going to interfere -- for instance, this is permissible |
| // if we are still single-threaded and have either not yet |
| // started allocating (nothing much to verify) or we have |
| // started allocating but are now a full-fledged JavaThread |
| // (and have thus made our TLAB's) available for filling. |
| assert(SafepointSynchronize::is_at_safepoint() || |
| !is_init_completed(), |
| "Should only be called at a safepoint or at start-up" |
| " otherwise concurrent mutator activity may make heap " |
| " unparsable again"); |
| const bool use_tlab = UseTLAB; |
| const bool deferred = _defer_initial_card_mark; |
| // The main thread starts allocating via a TLAB even before it |
| // has added itself to the threads list at vm boot-up. |
| assert(!use_tlab || Threads::first() != NULL, |
| "Attempt to fill tlabs before main thread has been added" |
| " to threads list is doomed to failure!"); |
| for (JavaThread *thread = Threads::first(); thread; thread = thread->next()) { |
| if (use_tlab) thread->tlab().make_parsable(retire_tlabs); |
| #ifdef COMPILER2 |
| // The deferred store barriers must all have been flushed to the |
| // card-table (or other remembered set structure) before GC starts |
| // processing the card-table (or other remembered set). |
| if (deferred) flush_deferred_store_barrier(thread); |
| #else |
| assert(!deferred, "Should be false"); |
| assert(thread->deferred_card_mark().is_empty(), "Should be empty"); |
| #endif |
| } |
| } |
| |
| void CollectedHeap::accumulate_statistics_all_tlabs() { |
| if (UseTLAB) { |
| assert(SafepointSynchronize::is_at_safepoint() || |
| !is_init_completed(), |
| "should only accumulate statistics on tlabs at safepoint"); |
| |
| ThreadLocalAllocBuffer::accumulate_statistics_before_gc(); |
| } |
| } |
| |
| void CollectedHeap::resize_all_tlabs() { |
| if (UseTLAB) { |
| assert(SafepointSynchronize::is_at_safepoint() || |
| !is_init_completed(), |
| "should only resize tlabs at safepoint"); |
| |
| ThreadLocalAllocBuffer::resize_all_tlabs(); |
| } |
| } |
| |
| void CollectedHeap::pre_full_gc_dump() { |
| if (HeapDumpBeforeFullGC) { |
| TraceTime tt("Heap Dump: ", PrintGCDetails, false, gclog_or_tty); |
| // We are doing a "major" collection and a heap dump before |
| // major collection has been requested. |
| HeapDumper::dump_heap(); |
| } |
| if (PrintClassHistogramBeforeFullGC) { |
| TraceTime tt("Class Histogram: ", PrintGCDetails, true, gclog_or_tty); |
| VM_GC_HeapInspection inspector(gclog_or_tty, false /* ! full gc */, false /* ! prologue */); |
| inspector.doit(); |
| } |
| } |
| |
| void CollectedHeap::post_full_gc_dump() { |
| if (HeapDumpAfterFullGC) { |
| TraceTime tt("Heap Dump", PrintGCDetails, false, gclog_or_tty); |
| HeapDumper::dump_heap(); |
| } |
| if (PrintClassHistogramAfterFullGC) { |
| TraceTime tt("Class Histogram", PrintGCDetails, true, gclog_or_tty); |
| VM_GC_HeapInspection inspector(gclog_or_tty, false /* ! full gc */, false /* ! prologue */); |
| inspector.doit(); |
| } |
| } |