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/*
* Copyright (c) 2015, 2020, Red Hat, Inc. All rights reserved.
+ * Copyright Amazon.com Inc. 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.
#include "gc/shenandoah/shenandoahCollectionSet.inline.hpp"
#include "gc/shenandoah/shenandoahForwarding.inline.hpp"
#include "gc/shenandoah/shenandoahWorkGroup.hpp"
#include "gc/shenandoah/shenandoahHeapRegionSet.inline.hpp"
#include "gc/shenandoah/shenandoahHeapRegion.inline.hpp"
- #include "gc/shenandoah/shenandoahControlThread.hpp"
+ #include "gc/shenandoah/shenandoahGenerationalControlThread.hpp"
#include "gc/shenandoah/shenandoahMarkingContext.inline.hpp"
#include "gc/shenandoah/shenandoahThreadLocalData.hpp"
+ #include "gc/shenandoah/shenandoahScanRemembered.inline.hpp"
+ #include "gc/shenandoah/mode/shenandoahMode.hpp"
#include "oops/compressedOops.inline.hpp"
#include "oops/oop.inline.hpp"
#include "runtime/atomic.hpp"
#include "runtime/javaThread.hpp"
#include "runtime/prefetch.inline.hpp"
+ #include "runtime/objectMonitor.inline.hpp"
#include "utilities/copy.hpp"
#include "utilities/globalDefinitions.hpp"
inline ShenandoahHeap* ShenandoahHeap::heap() {
return named_heap<ShenandoahHeap>(CollectedHeap::Shenandoah);
}
}
return cancelled_gc();
}
- inline void ShenandoahHeap::clear_cancelled_gc() {
+ inline void ShenandoahHeap::clear_cancelled_gc(bool clear_oom_handler) {
_cancelled_gc.set(CANCELLABLE);
- _oom_evac_handler.clear();
+ if (_cancel_requested_time > 0) {
+ double cancel_time = os::elapsedTime() - _cancel_requested_time;
+ log_info(gc)("GC cancellation took %.3fs", cancel_time);
+ _cancel_requested_time = 0;
+ }
+
+ if (clear_oom_handler) {
+ _oom_evac_handler.clear();
+ }
}
inline HeapWord* ShenandoahHeap::allocate_from_gclab(Thread* thread, size_t size) {
assert(UseTLAB, "TLABs should be enabled");
}
HeapWord* obj = gclab->allocate(size);
if (obj != nullptr) {
return obj;
}
- // Otherwise...
return allocate_from_gclab_slow(thread, size);
}
+ inline HeapWord* ShenandoahHeap::allocate_from_plab(Thread* thread, size_t size, bool is_promotion) {
+ assert(UseTLAB, "TLABs should be enabled");
+
+ PLAB* plab = ShenandoahThreadLocalData::plab(thread);
+ HeapWord* obj;
+
+ if (plab == nullptr) {
+ assert(!thread->is_Java_thread() && !thread->is_Worker_thread(), "Performance: thread should have PLAB: %s", thread->name());
+ // No PLABs in this thread, fallback to shared allocation
+ return nullptr;
+ } else if (is_promotion && !ShenandoahThreadLocalData::allow_plab_promotions(thread)) {
+ return nullptr;
+ }
+ // if plab->word_size() <= 0, thread's plab not yet initialized for this pass, so allow_plab_promotions() is not trustworthy
+ obj = plab->allocate(size);
+ if ((obj == nullptr) && (plab->words_remaining() < ShenandoahGenerationalHeap::heap()->plab_min_size())) {
+ // allocate_from_plab_slow will establish allow_plab_promotions(thread) for future invocations
+ obj = allocate_from_plab_slow(thread, size, is_promotion);
+ }
+ // if plab->words_remaining() >= ShenGenHeap::heap()->plab_min_size(), just return nullptr so we can use a shared allocation
+ if (obj == nullptr) {
+ return nullptr;
+ }
+
+ if (is_promotion) {
+ ShenandoahThreadLocalData::add_to_plab_promoted(thread, size * HeapWordSize);
+ } else {
+ ShenandoahThreadLocalData::add_to_plab_evacuated(thread, size * HeapWordSize);
+ }
+ return obj;
+ }
+
+ inline ShenandoahAgeCensus* ShenandoahHeap::age_census() const {
+ assert(mode()->is_generational(), "Only in generational mode");
+ assert(_age_census != nullptr, "Error: not initialized");
+ return _age_census;
+ }
+
inline oop ShenandoahHeap::evacuate_object(oop p, Thread* thread) {
- if (ShenandoahThreadLocalData::is_oom_during_evac(Thread::current())) {
+ assert(thread == Thread::current(), "Expected thread parameter to be current thread.");
+ if (ShenandoahThreadLocalData::is_oom_during_evac(thread)) {
// This thread went through the OOM during evac protocol and it is safe to return
// the forward pointer. It must not attempt to evacuate any more.
return ShenandoahBarrierSet::resolve_forwarded(p);
}
assert(ShenandoahThreadLocalData::is_evac_allowed(thread), "must be enclosed in oom-evac scope");
- size_t size = p->size();
-
- assert(!heap_region_containing(p)->is_humongous(), "never evacuate humongous objects");
-
- bool alloc_from_gclab = true;
- HeapWord* copy = nullptr;
+ ShenandoahHeapRegion* r = heap_region_containing(p);
+ assert(!r->is_humongous(), "never evacuate humongous objects");
- #ifdef ASSERT
- if (ShenandoahOOMDuringEvacALot &&
- (os::random() & 1) == 0) { // Simulate OOM every ~2nd slow-path call
- copy = nullptr;
- } else {
- #endif
- if (UseTLAB) {
- copy = allocate_from_gclab(thread, size);
+ ShenandoahAffiliation target_gen = r->affiliation();
+ if (mode()->is_generational() && ShenandoahHeap::heap()->is_gc_generation_young() &&
+ target_gen == YOUNG_GENERATION) {
+ markWord mark = p->mark();
+ if (mark.is_marked()) {
+ // Already forwarded.
+ return ShenandoahBarrierSet::resolve_forwarded(p);
}
- if (copy == nullptr) {
- ShenandoahAllocRequest req = ShenandoahAllocRequest::for_shared_gc(size);
- copy = allocate_memory(req);
- alloc_from_gclab = false;
+ if (mark.has_displaced_mark_helper()) {
+ // We don't want to deal with MT here just to ensure we read the right mark word.
+ // Skip the potential promotion attempt for this one.
+ } else if (r->age() + mark.age() >= age_census()->tenuring_threshold()) {
+ oop result = try_evacuate_object(p, thread, r, OLD_GENERATION);
+ if (result != nullptr) {
+ return result;
+ }
+ // If we failed to promote this aged object, we'll fall through to code below and evacuate to young-gen.
}
- #ifdef ASSERT
}
- #endif
+ return try_evacuate_object(p, thread, r, target_gen);
+ }
+
+ void ShenandoahHeap::increase_object_age(oop obj, uint additional_age) {
+ // This operates on new copy of an object. This means that the object's mark-word
+ // is thread-local and therefore safe to access. However, when the mark is
+ // displaced (i.e. stack-locked or monitor-locked), then it must be considered
+ // a shared memory location. It can be accessed by other threads.
+ // In particular, a competing evacuating thread can succeed to install its copy
+ // as the forwardee and continue to unlock the object, at which point 'our'
+ // write to the foreign stack-location would potentially over-write random
+ // information on that stack. Writing to a monitor is less problematic,
+ // but still not safe: while the ObjectMonitor would not randomly disappear,
+ // the other thread would also write to the same displaced header location,
+ // possibly leading to increase the age twice.
+ // For all these reasons, we take the conservative approach and not attempt
+ // to increase the age when the header is displaced.
+ markWord w = obj->mark();
+ // The mark-word has been copied from the original object. It can not be
+ // inflating, because inflation can not be interrupted by a safepoint,
+ // and after a safepoint, a Java thread would first have to successfully
+ // evacuate the object before it could inflate the monitor.
+ assert(!w.is_being_inflated() || LockingMode == LM_LIGHTWEIGHT, "must not inflate monitor before evacuation of object succeeds");
+ // It is possible that we have copied the object after another thread has
+ // already successfully completed evacuation. While harmless (we would never
+ // publish our copy), don't even attempt to modify the age when that
+ // happens.
+ if (!w.has_displaced_mark_helper() && !w.is_marked()) {
+ w = w.set_age(MIN2(markWord::max_age, w.age() + additional_age));
+ obj->set_mark(w);
+ }
+ }
- if (copy == nullptr) {
- control_thread()->handle_alloc_failure_evac(size);
+ // Return the object's age, or a sentinel value when the age can't
+ // necessarily be determined because of concurrent locking by the
+ // mutator
+ uint ShenandoahHeap::get_object_age(oop obj) {
+ // This is impossible to do unless we "freeze" ABA-type oscillations
+ // With Lilliput, we can do this more easily.
+ markWord w = obj->mark();
+ assert(!w.is_marked(), "must not be forwarded");
+ if (w.has_monitor()) {
+ w = w.monitor()->header();
+ } else if (w.is_being_inflated() || w.has_displaced_mark_helper()) {
+ // Informs caller that we aren't able to determine the age
+ return markWord::max_age + 1; // sentinel
+ }
+ assert(w.age() <= markWord::max_age, "Impossible!");
+ return w.age();
+ }
- _oom_evac_handler.handle_out_of_memory_during_evacuation();
+ bool ShenandoahHeap::is_in(const void* p) const {
+ HeapWord* heap_base = (HeapWord*) base();
+ HeapWord* last_region_end = heap_base + ShenandoahHeapRegion::region_size_words() * num_regions();
+ return p >= heap_base && p < last_region_end;
+ }
- return ShenandoahBarrierSet::resolve_forwarded(p);
+ inline bool ShenandoahHeap::is_in_active_generation(oop obj) const {
+ if (!mode()->is_generational()) {
+ // everything is the same single generation
+ return true;
}
- // Copy the object:
- Copy::aligned_disjoint_words(cast_from_oop<HeapWord*>(p), copy, size);
-
- // Try to install the new forwarding pointer.
- oop copy_val = cast_to_oop(copy);
- ContinuationGCSupport::relativize_stack_chunk(copy_val);
-
- oop result = ShenandoahForwarding::try_update_forwardee(p, copy_val);
- if (result == copy_val) {
- // Successfully evacuated. Our copy is now the public one!
- shenandoah_assert_correct(nullptr, copy_val);
- return copy_val;
- } else {
- // Failed to evacuate. We need to deal with the object that is left behind. Since this
- // new allocation is certainly after TAMS, it will be considered live in the next cycle.
- // But if it happens to contain references to evacuated regions, those references would
- // not get updated for this stale copy during this cycle, and we will crash while scanning
- // it the next cycle.
- //
- // For GCLAB allocations, it is enough to rollback the allocation ptr. Either the next
- // object will overwrite this stale copy, or the filler object on LAB retirement will
- // do this. For non-GCLAB allocations, we have no way to retract the allocation, and
- // have to explicitly overwrite the copy with the filler object. With that overwrite,
- // we have to keep the fwdptr initialized and pointing to our (stale) copy.
- if (alloc_from_gclab) {
- ShenandoahThreadLocalData::gclab(thread)->undo_allocation(copy, size);
- } else {
- fill_with_object(copy, size);
- shenandoah_assert_correct(nullptr, copy_val);
- }
- shenandoah_assert_correct(nullptr, result);
- return result;
+ if (active_generation() == nullptr) {
+ // no collection is happening, only expect this to be called
+ // when concurrent processing is active, but that could change
+ return false;
+ }
+
+ assert(is_in(obj), "only check if is in active generation for objects (" PTR_FORMAT ") in heap", p2i(obj));
+ assert((active_generation() == (ShenandoahGeneration*) old_generation()) ||
+ (active_generation() == (ShenandoahGeneration*) young_generation()) ||
+ (active_generation() == global_generation()), "Active generation must be old, young, or global");
+
+ size_t index = heap_region_containing(obj)->index();
+ switch (_affiliations[index]) {
+ case ShenandoahAffiliation::FREE:
+ // Free regions are in Old, Young, Global
+ return true;
+ case ShenandoahAffiliation::YOUNG_GENERATION:
+ // Young regions are in young_generation and global_generation, not in old_generation
+ return (active_generation() != (ShenandoahGeneration*) old_generation());
+ case ShenandoahAffiliation::OLD_GENERATION:
+ // Old regions are in old_generation and global_generation, not in young_generation
+ return (active_generation() != (ShenandoahGeneration*) young_generation());
+ default:
+ assert(false, "Bad affiliation (%d) for region " SIZE_FORMAT, _affiliations[index], index);
+ return false;
}
}
+ inline bool ShenandoahHeap::is_in_young(const void* p) const {
+ return is_in(p) && (_affiliations[heap_region_index_containing(p)] == ShenandoahAffiliation::YOUNG_GENERATION);
+ }
+
+ inline bool ShenandoahHeap::is_in_old(const void* p) const {
+ return is_in(p) && (_affiliations[heap_region_index_containing(p)] == ShenandoahAffiliation::OLD_GENERATION);
+ }
+
+ inline bool ShenandoahHeap::is_old(oop obj) const {
+ return is_gc_generation_young() && is_in_old(obj);
+ }
+
+ inline ShenandoahAffiliation ShenandoahHeap::region_affiliation(const ShenandoahHeapRegion *r) {
+ return (ShenandoahAffiliation) _affiliations[r->index()];
+ }
+
+ inline void ShenandoahHeap::assert_lock_for_affiliation(ShenandoahAffiliation orig_affiliation,
+ ShenandoahAffiliation new_affiliation) {
+ // A lock is required when changing from FREE to NON-FREE. Though it may be possible to elide the lock when
+ // transitioning from in-use to FREE, the current implementation uses a lock for this transition. A lock is
+ // not required to change from YOUNG to OLD (i.e. when promoting humongous region).
+ //
+ // new_affiliation is: FREE YOUNG OLD
+ // orig_affiliation is: FREE X L L
+ // YOUNG L X
+ // OLD L X X
+ // X means state transition won't happen (so don't care)
+ // L means lock should be held
+ // Blank means no lock required because affiliation visibility will not be required until subsequent safepoint
+ //
+ // Note: during full GC, all transitions between states are possible. During Full GC, we should be in a safepoint.
+
+ if ((orig_affiliation == ShenandoahAffiliation::FREE) || (new_affiliation == ShenandoahAffiliation::FREE)) {
+ shenandoah_assert_heaplocked_or_fullgc_safepoint();
+ }
+ }
+
+ inline void ShenandoahHeap::set_affiliation(ShenandoahHeapRegion* r, ShenandoahAffiliation new_affiliation) {
+ #ifdef ASSERT
+ assert_lock_for_affiliation(region_affiliation(r), new_affiliation);
+ #endif
+ _affiliations[r->index()] = (uint8_t) new_affiliation;
+ }
+
+ inline ShenandoahAffiliation ShenandoahHeap::region_affiliation(size_t index) {
+ return (ShenandoahAffiliation) _affiliations[index];
+ }
+
inline bool ShenandoahHeap::requires_marking(const void* entry) const {
oop obj = cast_to_oop(entry);
return !_marking_context->is_marked_strong(obj);
}
inline bool ShenandoahHeap::in_collection_set_loc(void* p) const {
assert(collection_set() != nullptr, "Sanity");
return collection_set()->is_in_loc(p);
}
+
inline bool ShenandoahHeap::is_stable() const {
return _gc_state.is_clear();
}
inline bool ShenandoahHeap::is_idle() const {
inline bool ShenandoahHeap::is_concurrent_mark_in_progress() const {
return _gc_state.is_set(MARKING);
}
+ inline bool ShenandoahHeap::is_concurrent_young_mark_in_progress() const {
+ return _gc_state.is_set(YOUNG_MARKING);
+ }
+
+ inline bool ShenandoahHeap::is_concurrent_old_mark_in_progress() const {
+ return _gc_state.is_set(OLD_MARKING);
+ }
+
inline bool ShenandoahHeap::is_evacuation_in_progress() const {
return _gc_state.is_set(EVACUATION);
}
inline bool ShenandoahHeap::is_degenerated_gc_in_progress() const {
inline bool ShenandoahHeap::is_concurrent_weak_root_in_progress() const {
return _gc_state.is_set(WEAK_ROOTS);
}
+ inline bool ShenandoahHeap::is_aging_cycle() const {
+ return _is_aging_cycle.is_set();
+ }
+
template<class T>
inline void ShenandoahHeap::marked_object_iterate(ShenandoahHeapRegion* region, T* cl) {
marked_object_iterate(region, cl, region->top());
}
template<class T>
inline void ShenandoahHeap::marked_object_iterate(ShenandoahHeapRegion* region, T* cl, HeapWord* limit) {
assert(! region->is_humongous_continuation(), "no humongous continuation regions here");
- ShenandoahMarkingContext* const ctx = complete_marking_context();
- assert(ctx->is_complete(), "sanity");
+ ShenandoahMarkingContext* const ctx = marking_context();
HeapWord* tams = ctx->top_at_mark_start(region);
size_t skip_bitmap_delta = 1;
HeapWord* start = region->bottom();
} else {
return nullptr;
}
}
- inline void ShenandoahHeap::mark_complete_marking_context() {
- _marking_context->mark_complete();
- }
-
- inline void ShenandoahHeap::mark_incomplete_marking_context() {
- _marking_context->mark_incomplete();
- }
-
inline ShenandoahMarkingContext* ShenandoahHeap::complete_marking_context() const {
assert (_marking_context->is_complete()," sanity");
return _marking_context;
}
inline ShenandoahMarkingContext* ShenandoahHeap::marking_context() const {
return _marking_context;
}
+ inline void ShenandoahHeap::clear_cards_for(ShenandoahHeapRegion* region) {
+ if (mode()->is_generational()) {
+ _card_scan->mark_range_as_empty(region->bottom(), pointer_delta(region->end(), region->bottom()));
+ }
+ }
+
+ inline void ShenandoahHeap::mark_card_as_dirty(void* location) {
+ if (mode()->is_generational()) {
+ _card_scan->mark_card_as_dirty((HeapWord*)location);
+ }
+ }
+
#endif // SHARE_GC_SHENANDOAH_SHENANDOAHHEAP_INLINE_HPP
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