| /* |
| * Copyright 2001-2007 Sun Microsystems, Inc. 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, |
| * CA 95054 USA or visit www.sun.com if you need additional information or |
| * have any questions. |
| * |
| */ |
| |
| // 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 BarrierSet; |
| class ThreadClosure; |
| class AdaptiveSizePolicy; |
| class Thread; |
| |
| // |
| // CollectedHeap |
| // SharedHeap |
| // GenCollectedHeap |
| // G1CollectedHeap |
| // ParallelScavengeHeap |
| // |
| class CollectedHeap : public CHeapObj { |
| friend class VMStructs; |
| friend class IsGCActiveMark; // Block structured external access to _is_gc_active |
| |
| #ifdef ASSERT |
| static int _fire_out_of_memory_count; |
| #endif |
| |
| protected: |
| MemRegion _reserved; |
| BarrierSet* _barrier_set; |
| bool _is_gc_active; |
| unsigned int _total_collections; // ... started |
| unsigned int _total_full_collections; // ... started |
| size_t _max_heap_capacity; |
| 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(); |
| |
| // Create a new tlab |
| virtual HeapWord* allocate_new_tlab(size_t size); |
| |
| // Fix up tlabs to make the heap well-formed again, |
| // optionally retiring the tlabs. |
| virtual void fill_all_tlabs(bool retire); |
| |
| // Accumulate statistics on all tlabs. |
| virtual void accumulate_statistics_all_tlabs(); |
| |
| // Reinitialize tlabs before resuming mutators. |
| virtual void resize_all_tlabs(); |
| |
| debug_only(static void check_for_valid_allocation_state();) |
| |
| protected: |
| // Allocate from the current thread's TLAB, with broken-out slow path. |
| inline static HeapWord* allocate_from_tlab(Thread* thread, size_t size); |
| static HeapWord* allocate_from_tlab_slow(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(size_t size, bool is_noref, TRAPS); |
| |
| // Like allocate_init, but the block returned by a successful allocation |
| // is guaranteed initialized to zeros. |
| inline static HeapWord* common_mem_allocate_init(size_t size, bool is_noref, TRAPS); |
| |
| // Same as common_mem version, except memory is allocated in the permanent area |
| // If there is no permanent area, revert to common_mem_allocate_noinit |
| inline static HeapWord* common_permanent_mem_allocate_noinit(size_t size, TRAPS); |
| |
| // Same as common_mem version, except memory is allocated in the permanent area |
| // If there is no permanent area, revert to common_mem_allocate_init |
| inline static HeapWord* common_permanent_mem_allocate_init(size_t size, TRAPS); |
| |
| // Helper functions for (VM) allocation. |
| inline static void post_allocation_setup_common(KlassHandle klass, |
| HeapWord* obj, size_t size); |
| inline static void post_allocation_setup_no_klass_install(KlassHandle klass, |
| HeapWord* objPtr, |
| size_t size); |
| |
| inline static void post_allocation_setup_obj(KlassHandle klass, |
| HeapWord* obj, size_t size); |
| |
| inline static void post_allocation_setup_array(KlassHandle klass, |
| HeapWord* obj, size_t size, |
| int length); |
| |
| // Clears an allocated object. |
| inline static void init_obj(HeapWord* obj, size_t size); |
| |
| // 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; |
| |
| public: |
| enum Name { |
| Abstract, |
| SharedHeap, |
| GenCollectedHeap, |
| ParallelScavengeHeap, |
| G1CollectedHeap |
| }; |
| |
| 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; |
| |
| MemRegion reserved_region() const { return _reserved; } |
| |
| // Return the number of bytes currently reserved, committed, and used, |
| // respectively, for holding objects. |
| size_t reserved_obj_bytes() const { return _reserved.byte_size(); } |
| |
| // Future cleanup here. The following functions should specify bytes or |
| // heapwords as part of their signature. |
| 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; |
| |
| virtual size_t permanent_capacity() const = 0; |
| virtual size_t permanent_used() 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., |
| // perm gen space or, 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" if "p" points to the head of an allocated object in 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); |
| } |
| |
| // 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); |
| } |
| |
| // Returns "TRUE" if "p" is allocated as "permanent" data. |
| // If the heap does not use "permanent" data, returns the same |
| // value is_in_reserved() would return. |
| // NOTE: this actually returns true if "p" is in reserved space |
| // for the space not that it is actually allocated (i.e. in committed |
| // space). If you need the more conservative answer use is_permanent(). |
| virtual bool is_in_permanent(const void *p) const = 0; |
| |
| // Returns "TRUE" if "p" is in the committed area of "permanent" data. |
| // If the heap does not use "permanent" data, returns the same |
| // value is_in() would return. |
| virtual bool is_permanent(const void *p) const = 0; |
| |
| bool is_in_permanent_or_null(const void *p) const { |
| return p == NULL || is_in_permanent(p); |
| } |
| |
| // Returns "TRUE" if "p" is a method oop in the |
| // current heap, with high probability. This predicate |
| // is not stable, in general. |
| bool is_valid_method(oop p) const; |
| |
| 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; } |
| |
| // Preload classes into the shared portion of the heap, and then dump |
| // that data to a file so that it can be loaded directly by another |
| // VM (then terminate). |
| virtual void preload_and_dump(TRAPS) { ShouldNotReachHere(); } |
| |
| // 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 large_typearray_allocate(KlassHandle klass, int size, int length, TRAPS); |
| |
| // Special obj/array allocation facilities. |
| // Some heaps may want to manage "permanent" data uniquely. These default |
| // to the general routines if the heap does not support such handling. |
| inline static oop permanent_obj_allocate(KlassHandle klass, int size, TRAPS); |
| // permanent_obj_allocate_no_klass_install() does not do the installation of |
| // the klass pointer in the newly created object (as permanent_obj_allocate() |
| // above does). This allows for a delay in the installation of the klass |
| // pointer that is needed during the create of klassKlass's. The |
| // method post_allocation_install_obj_klass() is used to install the |
| // klass pointer. |
| inline static oop permanent_obj_allocate_no_klass_install(KlassHandle klass, |
| int size, |
| TRAPS); |
| inline static void post_allocation_install_obj_klass(KlassHandle klass, |
| oop obj, |
| int size); |
| inline static oop permanent_array_allocate(KlassHandle klass, int size, int length, TRAPS); |
| |
| // Raw memory allocation facilities |
| // The obj and array allocate methods are covers for these methods. |
| // The permanent allocation method should default to mem_allocate if |
| // permanent memory isn't supported. |
| virtual HeapWord* mem_allocate(size_t size, |
| bool is_noref, |
| bool is_tlab, |
| bool* gc_overhead_limit_was_exceeded) = 0; |
| virtual HeapWord* permanent_mem_allocate(size_t size) = 0; |
| |
| // The boundary between a "large" and "small" array of primitives, in words. |
| virtual size_t large_typearray_limit() = 0; |
| |
| // 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); |
| |
| // Return an estimate of the maximum allocation that could be performed |
| // without triggering any collection or expansion activity. In a |
| // generational collector, for example, this is probably the largest |
| // allocation that could be supported (without expansion) in the youngest |
| // generation. It is "unsafe" because no locks are taken; the result |
| // should be treated as an approximation, not a guarantee, for use in |
| // heuristic resizing decisions. |
| virtual size_t unsafe_max_alloc() = 0; |
| |
| // 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 { |
| return false; |
| } |
| // The amount of space available for thread-local allocation buffers. |
| virtual size_t tlab_capacity(Thread *thr) const { |
| guarantee(false, "thread-local allocation buffers not supported"); |
| return 0; |
| } |
| // 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. |
| virtual bool can_elide_tlab_store_barriers() const { |
| guarantee(kind() < CollectedHeap::G1CollectedHeap, "else change or refactor this"); |
| return true; |
| } |
| // 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_barrier(oop new_obj); |
| |
| // Can a compiler elide a store barrier when it writes |
| // a permanent oop into the heap? Applies when the compiler |
| // is storing x to the heap, where x->is_perm() is true. |
| virtual bool can_elide_permanent_oop_store_barriers() const; |
| |
| // Does this heap support heap inspection (+PrintClassHistogram?) |
| virtual bool supports_heap_inspection() const { |
| return false; // Until RFE 5023697 is implemented |
| } |
| |
| // 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; |
| |
| // 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) = 0; |
| |
| // 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; |
| |
| // Iterate over all the ref-containing fields of all objects, calling |
| // "cl.do_oop" on each. This includes objects in permanent memory. |
| virtual void oop_iterate(OopClosure* cl) = 0; |
| |
| // Iterate over all objects, calling "cl.do_object" on each. |
| // This includes objects in permanent memory. |
| virtual void object_iterate(ObjectClosure* cl) = 0; |
| |
| // Behaves the same as oop_iterate, except only traverses |
| // interior pointers contained in permanent memory. If there |
| // is no permanent memory, does nothing. |
| virtual void permanent_oop_iterate(OopClosure* cl) = 0; |
| |
| // Behaves the same as object_iterate, except only traverses |
| // object contained in permanent memory. If there is no |
| // permanent memory, does nothing. |
| virtual void permanent_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; |
| |
| virtual void print() const = 0; |
| virtual void print_on(outputStream* st) const = 0; |
| |
| // Print all GC threads (other than the VM thread) |
| // used by this heap. |
| virtual void print_gc_threads_on(outputStream* st) const = 0; |
| 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; |
| |
| // Heap verification |
| virtual void verify(bool allow_dirty, bool silent) = 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 ocurred. |
| 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 |
| }; |
| |
| // 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); |
| } |
| }; |