/* * Copyright (c) 2001, 2013, 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 "precompiled.hpp" #include "classfile/systemDictionary.hpp" #include "gc_implementation/shared/gcHeapSummary.hpp" #include "gc_implementation/shared/gcTrace.hpp" #include "gc_implementation/shared/gcTraceTime.hpp" #include "gc_implementation/shared/gcWhen.hpp" #include "gc_implementation/shared/vmGCOperations.hpp" #include "gc_interface/allocTracer.hpp" #include "gc_interface/collectedHeap.hpp" #include "gc_interface/collectedHeap.inline.hpp" #include "memory/metaspace.hpp" #include "oops/oop.inline.hpp" #include "oops/instanceMirrorKlass.hpp" #include "runtime/init.hpp" #include "runtime/thread.inline.hpp" #include "services/heapDumper.hpp" #ifdef ASSERT int CollectedHeap::_fire_out_of_memory_count = 0; #endif size_t CollectedHeap::_filler_array_max_size = 0; template <> void EventLogBase::print(outputStream* st, GCMessage& m) { st->print_cr("GC heap %s", m.is_before ? "before" : "after"); st->print_raw(m); } void GCHeapLog::log_heap(bool before) { if (!should_log()) { return; } double timestamp = fetch_timestamp(); MutexLockerEx ml(&_mutex, Mutex::_no_safepoint_check_flag); int index = compute_log_index(); _records[index].thread = NULL; // Its the GC thread so it's not that interesting. _records[index].timestamp = timestamp; _records[index].data.is_before = before; stringStream st(_records[index].data.buffer(), _records[index].data.size()); if (before) { Universe::print_heap_before_gc(&st, true); } else { Universe::print_heap_after_gc(&st, true); } } VirtualSpaceSummary CollectedHeap::create_heap_space_summary() { size_t capacity_in_words = capacity() / HeapWordSize; return VirtualSpaceSummary( reserved_region().start(), reserved_region().start() + capacity_in_words, reserved_region().end()); } GCHeapSummary CollectedHeap::create_heap_summary() { VirtualSpaceSummary heap_space = create_heap_space_summary(); return GCHeapSummary(heap_space, used()); } MetaspaceSummary CollectedHeap::create_metaspace_summary() { const MetaspaceSizes meta_space( MetaspaceAux::allocated_capacity_bytes(), MetaspaceAux::allocated_used_bytes(), MetaspaceAux::reserved_bytes()); const MetaspaceSizes data_space( MetaspaceAux::allocated_capacity_bytes(Metaspace::NonClassType), MetaspaceAux::allocated_used_bytes(Metaspace::NonClassType), MetaspaceAux::reserved_bytes(Metaspace::NonClassType)); const MetaspaceSizes class_space( MetaspaceAux::allocated_capacity_bytes(Metaspace::ClassType), MetaspaceAux::allocated_used_bytes(Metaspace::ClassType), MetaspaceAux::reserved_bytes(Metaspace::ClassType)); return MetaspaceSummary(meta_space, data_space, class_space); } void CollectedHeap::print_heap_before_gc() { if (PrintHeapAtGC) { Universe::print_heap_before_gc(); } if (_gc_heap_log != NULL) { _gc_heap_log->log_heap_before(); } } void CollectedHeap::print_heap_after_gc() { if (PrintHeapAtGC) { Universe::print_heap_after_gc(); } if (_gc_heap_log != NULL) { _gc_heap_log->log_heap_after(); } } void CollectedHeap::register_nmethod(nmethod* nm) { assert_locked_or_safepoint(CodeCache_lock); } void CollectedHeap::unregister_nmethod(nmethod* nm) { assert_locked_or_safepoint(CodeCache_lock); } void CollectedHeap::trace_heap(GCWhen::Type when, GCTracer* gc_tracer) { const GCHeapSummary& heap_summary = create_heap_summary(); const MetaspaceSummary& metaspace_summary = create_metaspace_summary(); gc_tracer->report_gc_heap_summary(when, heap_summary, metaspace_summary); } void CollectedHeap::trace_heap_before_gc(GCTracer* gc_tracer) { trace_heap(GCWhen::BeforeGC, gc_tracer); } void CollectedHeap::trace_heap_after_gc(GCTracer* gc_tracer) { trace_heap(GCWhen::AfterGC, gc_tracer); } // Memory state functions. CollectedHeap::CollectedHeap() : _n_par_threads(0) { 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. // Create the ring log if (LogEvents) { _gc_heap_log = new GCHeapLog(); } else { _gc_heap_log = NULL; } } // This interface assumes that it's being called by the // vm thread. It collects the heap assuming that the // heap lock is already held and that we are executing in // the context of the vm thread. void CollectedHeap::collect_as_vm_thread(GCCause::Cause cause) { assert(Thread::current()->is_VM_thread(), "Precondition#1"); assert(Heap_lock->is_locked(), "Precondition#2"); GCCauseSetter gcs(this, cause); switch (cause) { case GCCause::_heap_inspection: case GCCause::_heap_dump: case GCCause::_metadata_GC_threshold : { HandleMark hm; do_full_collection(false); // don't clear all soft refs break; } case GCCause::_last_ditch_collection: { HandleMark hm; do_full_collection(true); // do clear all soft refs break; } default: ShouldNotReachHere(); // Unexpected use of this function } } 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(KlassHandle klass, 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; } AllocTracer::send_allocation_in_new_tlab_event(klass, new_tlab_size * HeapWordSize, size * HeapWordSize); if (ZeroTLAB) { // ..and clear it. Copy::zero_to_words(obj, new_tlab_size); } else { // ...and zap just allocated object. #ifdef ASSERT // Skip mangling the space corresponding to the object header to // ensure that the returned space is not considered parsable by // any concurrent GC thread. size_t hdr_size = oopDesc::header_size(); Copy::fill_to_words(obj + hdr_size, new_tlab_size - hdr_size, badHeapWordVal); #endif // ASSERT } 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(old_obj->is_oop(true), "Not an oop"); 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 } #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); assert((int)len >= 0, err_msg("size too large " SIZE_FORMAT " becomes %d", words, (int)len)); // Set the length first for concurrent GC. ((arrayOop)start)->set_length((int)len); post_allocation_setup_common(Universe::intArrayKlassObj(), start); 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); } } 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(GCTimer* timer) { if (HeapDumpBeforeFullGC) { GCTraceTime tt("Heap Dump (before full gc): ", PrintGCDetails, false, timer); // We are doing a "major" collection and a heap dump before // major collection has been requested. HeapDumper::dump_heap(); } if (PrintClassHistogramBeforeFullGC) { GCTraceTime tt("Class Histogram (before full gc): ", PrintGCDetails, true, timer); VM_GC_HeapInspection inspector(gclog_or_tty, false /* ! full gc */); inspector.doit(); } } void CollectedHeap::post_full_gc_dump(GCTimer* timer) { if (HeapDumpAfterFullGC) { GCTraceTime tt("Heap Dump (after full gc): ", PrintGCDetails, false, timer); HeapDumper::dump_heap(); } if (PrintClassHistogramAfterFullGC) { GCTraceTime tt("Class Histogram (after full gc): ", PrintGCDetails, true, timer); VM_GC_HeapInspection inspector(gclog_or_tty, false /* ! full gc */); inspector.doit(); } } oop CollectedHeap::Class_obj_allocate(KlassHandle klass, int size, KlassHandle real_klass, TRAPS) { debug_only(check_for_valid_allocation_state()); assert(!Universe::heap()->is_gc_active(), "Allocation during gc not allowed"); assert(size >= 0, "int won't convert to size_t"); HeapWord* obj; assert(ScavengeRootsInCode > 0, "must be"); obj = common_mem_allocate_init(real_klass, size, CHECK_NULL); post_allocation_setup_common(klass, obj); assert(Universe::is_bootstrapping() || !((oop)obj)->is_array(), "must not be an array"); NOT_PRODUCT(Universe::heap()->check_for_bad_heap_word_value(obj, size)); oop mirror = (oop)obj; java_lang_Class::set_oop_size(mirror, size); // Setup indirections if (!real_klass.is_null()) { java_lang_Class::set_klass(mirror, real_klass()); real_klass->set_java_mirror(mirror); } InstanceMirrorKlass* mk = InstanceMirrorKlass::cast(mirror->klass()); assert(size == mk->instance_size(real_klass), "should have been set"); // notify jvmti and dtrace post_allocation_notify(klass, (oop)obj); return mirror; } /////////////// Unit tests /////////////// #ifndef PRODUCT void CollectedHeap::test_is_in() { CollectedHeap* heap = Universe::heap(); uintptr_t epsilon = (uintptr_t) MinObjAlignment; uintptr_t heap_start = (uintptr_t) heap->_reserved.start(); uintptr_t heap_end = (uintptr_t) heap->_reserved.end(); // Test that NULL is not in the heap. assert(!heap->is_in(NULL), "NULL is unexpectedly in the heap"); // Test that a pointer to before the heap start is reported as outside the heap. assert(heap_start >= ((uintptr_t)NULL + epsilon), "sanity"); void* before_heap = (void*)(heap_start - epsilon); assert(!heap->is_in(before_heap), err_msg("before_heap: " PTR_FORMAT " is unexpectedly in the heap", before_heap)); // Test that a pointer to after the heap end is reported as outside the heap. assert(heap_end <= ((uintptr_t)-1 - epsilon), "sanity"); void* after_heap = (void*)(heap_end + epsilon); assert(!heap->is_in(after_heap), err_msg("after_heap: " PTR_FORMAT " is unexpectedly in the heap", after_heap)); } #endif