8055091: CollectedHeap::_reserved usage should be cleaned up
Summary: Added an initialization function for _reserved.
Reviewed-by: mgerdin, jwilhelm
/*
* Copyright (c) 2001, 2014, 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
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*/
#ifndef SHARE_VM_GC_INTERFACE_COLLECTEDHEAP_HPP
#define SHARE_VM_GC_INTERFACE_COLLECTEDHEAP_HPP
#include "gc_interface/gcCause.hpp"
#include "gc_implementation/shared/gcWhen.hpp"
#include "memory/allocation.hpp"
#include "memory/barrierSet.hpp"
#include "runtime/handles.hpp"
#include "runtime/perfData.hpp"
#include "runtime/safepoint.hpp"
#include "utilities/events.hpp"
// A "CollectedHeap" is an implementation of a java heap for HotSpot. This
// is an abstract class: there may be many different kinds of heaps. This
// class defines the functions that a heap must implement, and contains
// infrastructure common to all heaps.
class AdaptiveSizePolicy;
class BarrierSet;
class CollectorPolicy;
class GCHeapSummary;
class GCTimer;
class GCTracer;
class MetaspaceSummary;
class Thread;
class ThreadClosure;
class VirtualSpaceSummary;
class nmethod;
class GCMessage : public FormatBuffer<1024> {
public:
bool is_before;
public:
GCMessage() {}
};
class GCHeapLog : public EventLogBase<GCMessage> {
private:
void log_heap(bool before);
public:
GCHeapLog() : EventLogBase<GCMessage>("GC Heap History") {}
void log_heap_before() {
log_heap(true);
}
void log_heap_after() {
log_heap(false);
}
};
//
// CollectedHeap
// SharedHeap
// GenCollectedHeap
// G1CollectedHeap
// ParallelScavengeHeap
//
class CollectedHeap : public CHeapObj<mtInternal> {
friend class VMStructs;
friend class IsGCActiveMark; // Block structured external access to _is_gc_active
private:
#ifdef ASSERT
static int _fire_out_of_memory_count;
#endif
// Used for filler objects (static, but initialized in ctor).
static size_t _filler_array_max_size;
GCHeapLog* _gc_heap_log;
// Used in support of ReduceInitialCardMarks; only consulted if COMPILER2 is being used
bool _defer_initial_card_mark;
MemRegion _reserved;
protected:
BarrierSet* _barrier_set;
bool _is_gc_active;
uint _n_par_threads;
unsigned int _total_collections; // ... started
unsigned int _total_full_collections; // ... started
NOT_PRODUCT(volatile size_t _promotion_failure_alot_count;)
NOT_PRODUCT(volatile size_t _promotion_failure_alot_gc_number;)
// Reason for current garbage collection. Should be set to
// a value reflecting no collection between collections.
GCCause::Cause _gc_cause;
GCCause::Cause _gc_lastcause;
PerfStringVariable* _perf_gc_cause;
PerfStringVariable* _perf_gc_lastcause;
// Constructor
CollectedHeap();
// Do common initializations that must follow instance construction,
// for example, those needing virtual calls.
// This code could perhaps be moved into initialize() but would
// be slightly more awkward because we want the latter to be a
// pure virtual.
void pre_initialize();
// Create a new tlab. All TLAB allocations must go through this.
virtual HeapWord* allocate_new_tlab(size_t size);
// Accumulate statistics on all tlabs.
virtual void accumulate_statistics_all_tlabs();
// Reinitialize tlabs before resuming mutators.
virtual void resize_all_tlabs();
// Allocate from the current thread's TLAB, with broken-out slow path.
inline static HeapWord* allocate_from_tlab(KlassHandle klass, Thread* thread, size_t size);
static HeapWord* allocate_from_tlab_slow(KlassHandle klass, Thread* thread, size_t size);
// Allocate an uninitialized block of the given size, or returns NULL if
// this is impossible.
inline static HeapWord* common_mem_allocate_noinit(KlassHandle klass, size_t size, TRAPS);
// Like allocate_init, but the block returned by a successful allocation
// is guaranteed initialized to zeros.
inline static HeapWord* common_mem_allocate_init(KlassHandle klass, size_t size, TRAPS);
// Helper functions for (VM) allocation.
inline static void post_allocation_setup_common(KlassHandle klass, HeapWord* obj);
inline static void post_allocation_setup_no_klass_install(KlassHandle klass,
HeapWord* objPtr);
inline static void post_allocation_setup_obj(KlassHandle klass, HeapWord* obj, int size);
inline static void post_allocation_setup_array(KlassHandle klass,
HeapWord* obj, int length);
// Clears an allocated object.
inline static void init_obj(HeapWord* obj, size_t size);
// Filler object utilities.
static inline size_t filler_array_hdr_size();
static inline size_t filler_array_min_size();
DEBUG_ONLY(static void fill_args_check(HeapWord* start, size_t words);)
DEBUG_ONLY(static void zap_filler_array(HeapWord* start, size_t words, bool zap = true);)
// Fill with a single array; caller must ensure filler_array_min_size() <=
// words <= filler_array_max_size().
static inline void fill_with_array(HeapWord* start, size_t words, bool zap = true);
// Fill with a single object (either an int array or a java.lang.Object).
static inline void fill_with_object_impl(HeapWord* start, size_t words, bool zap = true);
virtual void trace_heap(GCWhen::Type when, GCTracer* tracer);
// Verification functions
virtual void check_for_bad_heap_word_value(HeapWord* addr, size_t size)
PRODUCT_RETURN;
virtual void check_for_non_bad_heap_word_value(HeapWord* addr, size_t size)
PRODUCT_RETURN;
debug_only(static void check_for_valid_allocation_state();)
public:
enum Name {
Abstract,
SharedHeap,
GenCollectedHeap,
ParallelScavengeHeap,
G1CollectedHeap
};
static inline size_t filler_array_max_size() {
return _filler_array_max_size;
}
virtual CollectedHeap::Name kind() const { return CollectedHeap::Abstract; }
/**
* Returns JNI error code JNI_ENOMEM if memory could not be allocated,
* and JNI_OK on success.
*/
virtual jint initialize() = 0;
// In many heaps, there will be a need to perform some initialization activities
// after the Universe is fully formed, but before general heap allocation is allowed.
// This is the correct place to place such initialization methods.
virtual void post_initialize() = 0;
// Stop any onging concurrent work and prepare for exit.
virtual void stop() {}
void initialize_reserved_region(HeapWord *start, HeapWord *end);
MemRegion reserved_region() const { return _reserved; }
address base() const { return (address)reserved_region().start(); }
virtual size_t capacity() const = 0;
virtual size_t used() const = 0;
// Return "true" if the part of the heap that allocates Java
// objects has reached the maximal committed limit that it can
// reach, without a garbage collection.
virtual bool is_maximal_no_gc() const = 0;
// Support for java.lang.Runtime.maxMemory(): return the maximum amount of
// memory that the vm could make available for storing 'normal' java objects.
// This is based on the reserved address space, but should not include space
// that the vm uses internally for bookkeeping or temporary storage
// (e.g., in the case of the young gen, one of the survivor
// spaces).
virtual size_t max_capacity() const = 0;
// Returns "TRUE" if "p" points into the reserved area of the heap.
bool is_in_reserved(const void* p) const {
return _reserved.contains(p);
}
bool is_in_reserved_or_null(const void* p) const {
return p == NULL || is_in_reserved(p);
}
// Returns "TRUE" iff "p" points into the committed areas of the heap.
// Since this method can be expensive in general, we restrict its
// use to assertion checking only.
virtual bool is_in(const void* p) const = 0;
bool is_in_or_null(const void* p) const {
return p == NULL || is_in(p);
}
bool is_in_place(Metadata** p) {
return !Universe::heap()->is_in(p);
}
bool is_in_place(oop* p) { return Universe::heap()->is_in(p); }
bool is_in_place(narrowOop* p) {
oop o = oopDesc::load_decode_heap_oop_not_null(p);
return Universe::heap()->is_in((const void*)o);
}
// Let's define some terms: a "closed" subset of a heap is one that
//
// 1) contains all currently-allocated objects, and
//
// 2) is closed under reference: no object in the closed subset
// references one outside the closed subset.
//
// Membership in a heap's closed subset is useful for assertions.
// Clearly, the entire heap is a closed subset, so the default
// implementation is to use "is_in_reserved". But this may not be too
// liberal to perform useful checking. Also, the "is_in" predicate
// defines a closed subset, but may be too expensive, since "is_in"
// verifies that its argument points to an object head. The
// "closed_subset" method allows a heap to define an intermediate
// predicate, allowing more precise checking than "is_in_reserved" at
// lower cost than "is_in."
// One important case is a heap composed of disjoint contiguous spaces,
// such as the Garbage-First collector. Such heaps have a convenient
// closed subset consisting of the allocated portions of those
// contiguous spaces.
// Return "TRUE" iff the given pointer points into the heap's defined
// closed subset (which defaults to the entire heap).
virtual bool is_in_closed_subset(const void* p) const {
return is_in_reserved(p);
}
bool is_in_closed_subset_or_null(const void* p) const {
return p == NULL || is_in_closed_subset(p);
}
#ifdef ASSERT
// Returns true if "p" is in the part of the
// heap being collected.
virtual bool is_in_partial_collection(const void *p) = 0;
#endif
// An object is scavengable if its location may move during a scavenge.
// (A scavenge is a GC which is not a full GC.)
virtual bool is_scavengable(const void *p) = 0;
void set_gc_cause(GCCause::Cause v) {
if (UsePerfData) {
_gc_lastcause = _gc_cause;
_perf_gc_lastcause->set_value(GCCause::to_string(_gc_lastcause));
_perf_gc_cause->set_value(GCCause::to_string(v));
}
_gc_cause = v;
}
GCCause::Cause gc_cause() { return _gc_cause; }
// Number of threads currently working on GC tasks.
uint n_par_threads() { return _n_par_threads; }
// May be overridden to set additional parallelism.
virtual void set_par_threads(uint t) { _n_par_threads = t; };
// General obj/array allocation facilities.
inline static oop obj_allocate(KlassHandle klass, int size, TRAPS);
inline static oop array_allocate(KlassHandle klass, int size, int length, TRAPS);
inline static oop array_allocate_nozero(KlassHandle klass, int size, int length, TRAPS);
inline static void post_allocation_install_obj_klass(KlassHandle klass,
oop obj);
// Raw memory allocation facilities
// The obj and array allocate methods are covers for these methods.
// mem_allocate() should never be
// called to allocate TLABs, only individual objects.
virtual HeapWord* mem_allocate(size_t size,
bool* gc_overhead_limit_was_exceeded) = 0;
// Utilities for turning raw memory into filler objects.
//
// min_fill_size() is the smallest region that can be filled.
// fill_with_objects() can fill arbitrary-sized regions of the heap using
// multiple objects. fill_with_object() is for regions known to be smaller
// than the largest array of integers; it uses a single object to fill the
// region and has slightly less overhead.
static size_t min_fill_size() {
return size_t(align_object_size(oopDesc::header_size()));
}
static void fill_with_objects(HeapWord* start, size_t words, bool zap = true);
static void fill_with_object(HeapWord* start, size_t words, bool zap = true);
static void fill_with_object(MemRegion region, bool zap = true) {
fill_with_object(region.start(), region.word_size(), zap);
}
static void fill_with_object(HeapWord* start, HeapWord* end, bool zap = true) {
fill_with_object(start, pointer_delta(end, start), zap);
}
// Return the address "addr" aligned by "alignment_in_bytes" if such
// an address is below "end". Return NULL otherwise.
inline static HeapWord* align_allocation_or_fail(HeapWord* addr,
HeapWord* end,
unsigned short alignment_in_bytes);
// Some heaps may offer a contiguous region for shared non-blocking
// allocation, via inlined code (by exporting the address of the top and
// end fields defining the extent of the contiguous allocation region.)
// This function returns "true" iff the heap supports this kind of
// allocation. (Default is "no".)
virtual bool supports_inline_contig_alloc() const {
return false;
}
// These functions return the addresses of the fields that define the
// boundaries of the contiguous allocation area. (These fields should be
// physically near to one another.)
virtual HeapWord** top_addr() const {
guarantee(false, "inline contiguous allocation not supported");
return NULL;
}
virtual HeapWord** end_addr() const {
guarantee(false, "inline contiguous allocation not supported");
return NULL;
}
// Some heaps may be in an unparseable state at certain times between
// collections. This may be necessary for efficient implementation of
// certain allocation-related activities. Calling this function before
// attempting to parse a heap ensures that the heap is in a parsable
// state (provided other concurrent activity does not introduce
// unparsability). It is normally expected, therefore, that this
// method is invoked with the world stopped.
// NOTE: if you override this method, make sure you call
// super::ensure_parsability so that the non-generational
// part of the work gets done. See implementation of
// CollectedHeap::ensure_parsability and, for instance,
// that of GenCollectedHeap::ensure_parsability().
// The argument "retire_tlabs" controls whether existing TLABs
// are merely filled or also retired, thus preventing further
// allocation from them and necessitating allocation of new TLABs.
virtual void ensure_parsability(bool retire_tlabs);
// Section on thread-local allocation buffers (TLABs)
// If the heap supports thread-local allocation buffers, it should override
// the following methods:
// Returns "true" iff the heap supports thread-local allocation buffers.
// The default is "no".
virtual bool supports_tlab_allocation() const = 0;
// The amount of space available for thread-local allocation buffers.
virtual size_t tlab_capacity(Thread *thr) const = 0;
// The amount of used space for thread-local allocation buffers for the given thread.
virtual size_t tlab_used(Thread *thr) const = 0;
virtual size_t max_tlab_size() const;
// An estimate of the maximum allocation that could be performed
// for thread-local allocation buffers without triggering any
// collection or expansion activity.
virtual size_t unsafe_max_tlab_alloc(Thread *thr) const {
guarantee(false, "thread-local allocation buffers not supported");
return 0;
}
// Can a compiler initialize a new object without store barriers?
// This permission only extends from the creation of a new object
// via a TLAB up to the first subsequent safepoint. If such permission
// is granted for this heap type, the compiler promises to call
// defer_store_barrier() below on any slow path allocation of
// a new object for which such initializing store barriers will
// have been elided.
virtual bool can_elide_tlab_store_barriers() const = 0;
// If a compiler is eliding store barriers for TLAB-allocated objects,
// there is probably a corresponding slow path which can produce
// an object allocated anywhere. The compiler's runtime support
// promises to call this function on such a slow-path-allocated
// object before performing initializations that have elided
// store barriers. Returns new_obj, or maybe a safer copy thereof.
virtual oop new_store_pre_barrier(JavaThread* thread, oop new_obj);
// Answers whether an initializing store to a new object currently
// allocated at the given address doesn't need a store
// barrier. Returns "true" if it doesn't need an initializing
// store barrier; answers "false" if it does.
virtual bool can_elide_initializing_store_barrier(oop new_obj) = 0;
// If a compiler is eliding store barriers for TLAB-allocated objects,
// we will be informed of a slow-path allocation by a call
// to new_store_pre_barrier() above. Such a call precedes the
// initialization of the object itself, and no post-store-barriers will
// be issued. Some heap types require that the barrier strictly follows
// the initializing stores. (This is currently implemented by deferring the
// barrier until the next slow-path allocation or gc-related safepoint.)
// This interface answers whether a particular heap type needs the card
// mark to be thus strictly sequenced after the stores.
virtual bool card_mark_must_follow_store() const = 0;
// If the CollectedHeap was asked to defer a store barrier above,
// this informs it to flush such a deferred store barrier to the
// remembered set.
virtual void flush_deferred_store_barrier(JavaThread* thread);
// Does this heap support heap inspection (+PrintClassHistogram?)
virtual bool supports_heap_inspection() const = 0;
// Perform a collection of the heap; intended for use in implementing
// "System.gc". This probably implies as full a collection as the
// "CollectedHeap" supports.
virtual void collect(GCCause::Cause cause) = 0;
// Perform a full collection
virtual void do_full_collection(bool clear_all_soft_refs) = 0;
// 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.
virtual void collect_as_vm_thread(GCCause::Cause cause);
// Returns the barrier set for this heap
BarrierSet* barrier_set() { return _barrier_set; }
// Returns "true" iff there is a stop-world GC in progress. (I assume
// that it should answer "false" for the concurrent part of a concurrent
// collector -- dld).
bool is_gc_active() const { return _is_gc_active; }
// Total number of GC collections (started)
unsigned int total_collections() const { return _total_collections; }
unsigned int total_full_collections() const { return _total_full_collections;}
// Increment total number of GC collections (started)
// Should be protected but used by PSMarkSweep - cleanup for 1.4.2
void increment_total_collections(bool full = false) {
_total_collections++;
if (full) {
increment_total_full_collections();
}
}
void increment_total_full_collections() { _total_full_collections++; }
// Return the AdaptiveSizePolicy for the heap.
virtual AdaptiveSizePolicy* size_policy() = 0;
// Return the CollectorPolicy for the heap
virtual CollectorPolicy* collector_policy() const = 0;
void oop_iterate_no_header(OopClosure* cl);
// Iterate over all the ref-containing fields of all objects, calling
// "cl.do_oop" on each.
virtual void oop_iterate(ExtendedOopClosure* cl) = 0;
// Iterate over all objects, calling "cl.do_object" on each.
virtual void object_iterate(ObjectClosure* cl) = 0;
// Similar to object_iterate() except iterates only
// over live objects.
virtual void safe_object_iterate(ObjectClosure* cl) = 0;
// NOTE! There is no requirement that a collector implement these
// functions.
//
// A CollectedHeap is divided into a dense sequence of "blocks"; that is,
// each address in the (reserved) heap is a member of exactly
// one block. The defining characteristic of a block is that it is
// possible to find its size, and thus to progress forward to the next
// block. (Blocks may be of different sizes.) Thus, blocks may
// represent Java objects, or they might be free blocks in a
// free-list-based heap (or subheap), as long as the two kinds are
// distinguishable and the size of each is determinable.
// Returns the address of the start of the "block" that contains the
// address "addr". We say "blocks" instead of "object" since some heaps
// may not pack objects densely; a chunk may either be an object or a
// non-object.
virtual HeapWord* block_start(const void* addr) const = 0;
// Requires "addr" to be the start of a chunk, and returns its size.
// "addr + size" is required to be the start of a new chunk, or the end
// of the active area of the heap.
virtual size_t block_size(const HeapWord* addr) const = 0;
// Requires "addr" to be the start of a block, and returns "TRUE" iff
// the block is an object.
virtual bool block_is_obj(const HeapWord* addr) const = 0;
// Returns the longest time (in ms) that has elapsed since the last
// time that any part of the heap was examined by a garbage collection.
virtual jlong millis_since_last_gc() = 0;
// Perform any cleanup actions necessary before allowing a verification.
virtual void prepare_for_verify() = 0;
// Generate any dumps preceding or following a full gc
void pre_full_gc_dump(GCTimer* timer);
void post_full_gc_dump(GCTimer* timer);
VirtualSpaceSummary create_heap_space_summary();
GCHeapSummary create_heap_summary();
MetaspaceSummary create_metaspace_summary();
// Print heap information on the given outputStream.
virtual void print_on(outputStream* st) const = 0;
// The default behavior is to call print_on() on tty.
virtual void print() const {
print_on(tty);
}
// Print more detailed heap information on the given
// outputStream. The default behavior is to call print_on(). It is
// up to each subclass to override it and add any additional output
// it needs.
virtual void print_extended_on(outputStream* st) const {
print_on(st);
}
virtual void print_on_error(outputStream* st) const {
st->print_cr("Heap:");
print_extended_on(st);
st->cr();
_barrier_set->print_on(st);
}
// Print all GC threads (other than the VM thread)
// used by this heap.
virtual void print_gc_threads_on(outputStream* st) const = 0;
// The default behavior is to call print_gc_threads_on() on tty.
void print_gc_threads() {
print_gc_threads_on(tty);
}
// Iterator for all GC threads (other than VM thread)
virtual void gc_threads_do(ThreadClosure* tc) const = 0;
// Print any relevant tracing info that flags imply.
// Default implementation does nothing.
virtual void print_tracing_info() const = 0;
void print_heap_before_gc();
void print_heap_after_gc();
// Registering and unregistering an nmethod (compiled code) with the heap.
// Override with specific mechanism for each specialized heap type.
virtual void register_nmethod(nmethod* nm);
virtual void unregister_nmethod(nmethod* nm);
void trace_heap_before_gc(GCTracer* gc_tracer);
void trace_heap_after_gc(GCTracer* gc_tracer);
// Heap verification
virtual void verify(bool silent, VerifyOption option) = 0;
// Non product verification and debugging.
#ifndef PRODUCT
// Support for PromotionFailureALot. Return true if it's time to cause a
// promotion failure. The no-argument version uses
// this->_promotion_failure_alot_count as the counter.
inline bool promotion_should_fail(volatile size_t* count);
inline bool promotion_should_fail();
// Reset the PromotionFailureALot counters. Should be called at the end of a
// GC in which promotion failure occurred.
inline void reset_promotion_should_fail(volatile size_t* count);
inline void reset_promotion_should_fail();
#endif // #ifndef PRODUCT
#ifdef ASSERT
static int fired_fake_oom() {
return (CIFireOOMAt > 1 && _fire_out_of_memory_count >= CIFireOOMAt);
}
#endif
public:
// This is a convenience method that is used in cases where
// the actual number of GC worker threads is not pertinent but
// only whether there more than 0. Use of this method helps
// reduce the occurrence of ParallelGCThreads to uses where the
// actual number may be germane.
static bool use_parallel_gc_threads() { return ParallelGCThreads > 0; }
/////////////// Unit tests ///////////////
NOT_PRODUCT(static void test_is_in();)
};
// Class to set and reset the GC cause for a CollectedHeap.
class GCCauseSetter : StackObj {
CollectedHeap* _heap;
GCCause::Cause _previous_cause;
public:
GCCauseSetter(CollectedHeap* heap, GCCause::Cause cause) {
assert(SafepointSynchronize::is_at_safepoint(),
"This method manipulates heap state without locking");
_heap = heap;
_previous_cause = _heap->gc_cause();
_heap->set_gc_cause(cause);
}
~GCCauseSetter() {
assert(SafepointSynchronize::is_at_safepoint(),
"This method manipulates heap state without locking");
_heap->set_gc_cause(_previous_cause);
}
};
#endif // SHARE_VM_GC_INTERFACE_COLLECTEDHEAP_HPP