--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/hotspot/src/share/vm/memory/genCollectedHeap.hpp Sat Dec 01 00:00:00 2007 +0000
@@ -0,0 +1,491 @@
+/*
+ * Copyright 2000-2007 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.
+ *
+ */
+
+class SubTasksDone;
+
+// A "GenCollectedHeap" is a SharedHeap that uses generational
+// collection. It is represented with a sequence of Generation's.
+class GenCollectedHeap : public SharedHeap {
+ friend class GenCollectorPolicy;
+ friend class Generation;
+ friend class DefNewGeneration;
+ friend class TenuredGeneration;
+ friend class ConcurrentMarkSweepGeneration;
+ friend class CMSCollector;
+ friend class GenMarkSweep;
+ friend class VM_GenCollectForAllocation;
+ friend class VM_GenCollectFull;
+ friend class VM_GenCollectFullConcurrent;
+ friend class VM_GC_HeapInspection;
+ friend class VM_HeapDumper;
+ friend class HeapInspection;
+ friend class GCCauseSetter;
+ friend class VMStructs;
+public:
+ enum SomeConstants {
+ max_gens = 10
+ };
+
+ friend class VM_PopulateDumpSharedSpace;
+
+ protected:
+ // Fields:
+ static GenCollectedHeap* _gch;
+
+ private:
+ int _n_gens;
+ Generation* _gens[max_gens];
+ GenerationSpec** _gen_specs;
+
+ // The generational collector policy.
+ GenCollectorPolicy* _gen_policy;
+
+ // If a generation would bail out of an incremental collection,
+ // it sets this flag. If the flag is set, satisfy_failed_allocation
+ // will attempt allocating in all generations before doing a full GC.
+ bool _incremental_collection_will_fail;
+ bool _last_incremental_collection_failed;
+
+ // In support of ExplicitGCInvokesConcurrent functionality
+ unsigned int _full_collections_completed;
+
+ // Data structure for claiming the (potentially) parallel tasks in
+ // (gen-specific) strong roots processing.
+ SubTasksDone* _gen_process_strong_tasks;
+
+ // In block contents verification, the number of header words to skip
+ NOT_PRODUCT(static size_t _skip_header_HeapWords;)
+
+ // GC is not allowed during the dump of the shared classes. Keep track
+ // of this in order to provide an reasonable error message when terminating.
+ bool _preloading_shared_classes;
+
+protected:
+ // Directs each generation up to and including "collectedGen" to recompute
+ // its desired size.
+ void compute_new_generation_sizes(int collectedGen);
+
+ // Helper functions for allocation
+ HeapWord* attempt_allocation(size_t size,
+ bool is_tlab,
+ bool first_only);
+
+ // Helper function for two callbacks below.
+ // Considers collection of the first max_level+1 generations.
+ void do_collection(bool full,
+ bool clear_all_soft_refs,
+ size_t size,
+ bool is_tlab,
+ int max_level);
+
+ // Callback from VM_GenCollectForAllocation operation.
+ // This function does everything necessary/possible to satisfy an
+ // allocation request that failed in the youngest generation that should
+ // have handled it (including collection, expansion, etc.)
+ HeapWord* satisfy_failed_allocation(size_t size, bool is_tlab);
+
+ // Callback from VM_GenCollectFull operation.
+ // Perform a full collection of the first max_level+1 generations.
+ void do_full_collection(bool clear_all_soft_refs, int max_level);
+
+ // Does the "cause" of GC indicate that
+ // we absolutely __must__ clear soft refs?
+ bool must_clear_all_soft_refs();
+
+public:
+ GenCollectedHeap(GenCollectorPolicy *policy);
+
+ GCStats* gc_stats(int level) const;
+
+ // Returns JNI_OK on success
+ virtual jint initialize();
+ char* allocate(size_t alignment, PermanentGenerationSpec* perm_gen_spec,
+ size_t* _total_reserved, int* _n_covered_regions,
+ ReservedSpace* heap_rs);
+
+ // Does operations required after initialization has been done.
+ void post_initialize();
+
+ // Initialize ("weak") refs processing support
+ virtual void ref_processing_init();
+
+ virtual CollectedHeap::Name kind() const {
+ return CollectedHeap::GenCollectedHeap;
+ }
+
+ // The generational collector policy.
+ GenCollectorPolicy* gen_policy() const { return _gen_policy; }
+
+ // Adaptive size policy
+ virtual AdaptiveSizePolicy* size_policy() {
+ return gen_policy()->size_policy();
+ }
+
+ size_t capacity() const;
+ size_t used() const;
+
+ // Save the "used_region" for generations level and lower,
+ // and, if perm is true, for perm gen.
+ void save_used_regions(int level, bool perm);
+
+ size_t max_capacity() const;
+
+ HeapWord* mem_allocate(size_t size,
+ bool is_large_noref,
+ bool is_tlab,
+ bool* gc_overhead_limit_was_exceeded);
+
+ // We may support a shared contiguous allocation area, if the youngest
+ // generation does.
+ bool supports_inline_contig_alloc() const;
+ HeapWord** top_addr() const;
+ HeapWord** end_addr() const;
+
+ // Return an estimate of the maximum allocation that could be performed
+ // without triggering any collection activity. In a generational
+ // collector, for example, this is probably the largest allocation that
+ // could be supported in the youngest generation. It is "unsafe" because
+ // no locks are taken; the result should be treated as an approximation,
+ // not a guarantee.
+ size_t unsafe_max_alloc();
+
+ // Does this heap support heap inspection? (+PrintClassHistogram)
+ virtual bool supports_heap_inspection() const { return true; }
+
+ // Perform a full collection of the heap; intended for use in implementing
+ // "System.gc". This implies as full a collection as the CollectedHeap
+ // supports. Caller does not hold the Heap_lock on entry.
+ void collect(GCCause::Cause cause);
+
+ // 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 collect_as_vm_thread(GCCause::Cause cause);
+
+ // The same as above but assume that the caller holds the Heap_lock.
+ void collect_locked(GCCause::Cause cause);
+
+ // Perform a full collection of the first max_level+1 generations.
+ // Mostly used for testing purposes. Caller does not hold the Heap_lock on entry.
+ void collect(GCCause::Cause cause, int max_level);
+
+ // Returns "TRUE" iff "p" points into the allocated area of the heap.
+ // The methods is_in(), is_in_closed_subset() and is_in_youngest() may
+ // be expensive to compute in general, so, to prevent
+ // their inadvertent use in product jvm's, we restrict their use to
+ // assertion checking or verification only.
+ bool is_in(const void* p) const;
+
+ // override
+ bool is_in_closed_subset(const void* p) const {
+ if (UseConcMarkSweepGC) {
+ return is_in_reserved(p);
+ } else {
+ return is_in(p);
+ }
+ }
+
+ // Returns "TRUE" iff "p" points into the youngest generation.
+ bool is_in_youngest(void* p);
+
+ // Iteration functions.
+ void oop_iterate(OopClosure* cl);
+ void oop_iterate(MemRegion mr, OopClosure* cl);
+ void object_iterate(ObjectClosure* cl);
+ void object_iterate_since_last_GC(ObjectClosure* cl);
+ Space* space_containing(const void* addr) const;
+
+ // 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;
+
+ // 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. Assumes (and verifies in non-product
+ // builds) that addr is in the allocated part of the heap and is
+ // the start of a chunk.
+ virtual size_t block_size(const HeapWord* addr) const;
+
+ // Requires "addr" to be the start of a block, and returns "TRUE" iff
+ // the block is an object. Assumes (and verifies in non-product
+ // builds) that addr is in the allocated part of the heap and is
+ // the start of a chunk.
+ virtual bool block_is_obj(const HeapWord* addr) const;
+
+ // Section on TLAB's.
+ virtual bool supports_tlab_allocation() const;
+ virtual size_t tlab_capacity(Thread* thr) const;
+ virtual size_t unsafe_max_tlab_alloc(Thread* thr) const;
+ virtual HeapWord* allocate_new_tlab(size_t size);
+
+ // The "requestor" generation is performing some garbage collection
+ // action for which it would be useful to have scratch space. The
+ // requestor promises to allocate no more than "max_alloc_words" in any
+ // older generation (via promotion say.) Any blocks of space that can
+ // be provided are returned as a list of ScratchBlocks, sorted by
+ // decreasing size.
+ ScratchBlock* gather_scratch(Generation* requestor, size_t max_alloc_words);
+
+ size_t large_typearray_limit();
+
+ // Ensure parsability: override
+ virtual void ensure_parsability(bool retire_tlabs);
+
+ // Time in ms since the longest time a collector ran in
+ // in any generation.
+ virtual jlong millis_since_last_gc();
+
+ // Total number of full collections completed.
+ unsigned int total_full_collections_completed() {
+ assert(_full_collections_completed <= _total_full_collections,
+ "Can't complete more collections than were started");
+ return _full_collections_completed;
+ }
+
+ // Update above counter, as appropriate, at the end of a stop-world GC cycle
+ unsigned int update_full_collections_completed();
+ // Update above counter, as appropriate, at the end of a concurrent GC cycle
+ unsigned int update_full_collections_completed(unsigned int count);
+
+ // Update "time of last gc" for all constituent generations
+ // to "now".
+ void update_time_of_last_gc(jlong now) {
+ for (int i = 0; i < _n_gens; i++) {
+ _gens[i]->update_time_of_last_gc(now);
+ }
+ perm_gen()->update_time_of_last_gc(now);
+ }
+
+ // Update the gc statistics for each generation.
+ // "level" is the level of the lastest collection
+ void update_gc_stats(int current_level, bool full) {
+ for (int i = 0; i < _n_gens; i++) {
+ _gens[i]->update_gc_stats(current_level, full);
+ }
+ perm_gen()->update_gc_stats(current_level, full);
+ }
+
+ // Override.
+ bool no_gc_in_progress() { return !is_gc_active(); }
+
+ // Override.
+ void prepare_for_verify();
+
+ // Override.
+ void verify(bool allow_dirty, bool silent);
+
+ // Override.
+ void print() const;
+ void print_on(outputStream* st) const;
+ virtual void print_gc_threads_on(outputStream* st) const;
+ virtual void gc_threads_do(ThreadClosure* tc) const;
+ virtual void print_tracing_info() const;
+
+ // PrintGC, PrintGCDetails support
+ void print_heap_change(size_t prev_used) const;
+ void print_perm_heap_change(size_t perm_prev_used) const;
+
+ // The functions below are helper functions that a subclass of
+ // "CollectedHeap" can use in the implementation of its virtual
+ // functions.
+
+ class GenClosure : public StackObj {
+ public:
+ virtual void do_generation(Generation* gen) = 0;
+ };
+
+ // Apply "cl.do_generation" to all generations in the heap (not including
+ // the permanent generation). If "old_to_young" determines the order.
+ void generation_iterate(GenClosure* cl, bool old_to_young);
+
+ void space_iterate(SpaceClosure* cl);
+
+ // Return "true" if all generations (but perm) have reached the
+ // maximal committed limit that they can reach, without a garbage
+ // collection.
+ virtual bool is_maximal_no_gc() const;
+
+ // Return the generation before "gen", or else NULL.
+ Generation* prev_gen(Generation* gen) const {
+ int l = gen->level();
+ if (l == 0) return NULL;
+ else return _gens[l-1];
+ }
+
+ // Return the generation after "gen", or else NULL.
+ Generation* next_gen(Generation* gen) const {
+ int l = gen->level() + 1;
+ if (l == _n_gens) return NULL;
+ else return _gens[l];
+ }
+
+ Generation* get_gen(int i) const {
+ if (i >= 0 && i < _n_gens)
+ return _gens[i];
+ else
+ return NULL;
+ }
+
+ int n_gens() const {
+ assert(_n_gens == gen_policy()->number_of_generations(), "Sanity");
+ return _n_gens;
+ }
+
+ // Convenience function to be used in situations where the heap type can be
+ // asserted to be this type.
+ static GenCollectedHeap* heap();
+
+ void set_par_threads(int t);
+
+
+ // Invoke the "do_oop" method of one of the closures "not_older_gens"
+ // or "older_gens" on root locations for the generation at
+ // "level". (The "older_gens" closure is used for scanning references
+ // from older generations; "not_older_gens" is used everywhere else.)
+ // If "younger_gens_as_roots" is false, younger generations are
+ // not scanned as roots; in this case, the caller must be arranging to
+ // scan the younger generations itself. (For example, a generation might
+ // explicitly mark reachable objects in younger generations, to avoid
+ // excess storage retention.) If "collecting_perm_gen" is false, then
+ // roots that may only contain references to permGen objects are not
+ // scanned. The "so" argument determines which of the roots
+ // the closure is applied to:
+ // "SO_None" does none;
+ // "SO_AllClasses" applies the closure to all entries in the SystemDictionary;
+ // "SO_SystemClasses" to all the "system" classes and loaders;
+ // "SO_Symbols_and_Strings" applies the closure to all entries in
+ // SymbolsTable and StringTable.
+ void gen_process_strong_roots(int level, bool younger_gens_as_roots,
+ bool collecting_perm_gen,
+ SharedHeap::ScanningOption so,
+ OopsInGenClosure* older_gens,
+ OopsInGenClosure* not_older_gens);
+
+ // Apply "blk" to all the weak roots of the system. These include
+ // JNI weak roots, the code cache, system dictionary, symbol table,
+ // string table, and referents of reachable weak refs.
+ void gen_process_weak_roots(OopClosure* root_closure,
+ OopClosure* non_root_closure);
+
+ // Set the saved marks of generations, if that makes sense.
+ // In particular, if any generation might iterate over the oops
+ // in other generations, it should call this method.
+ void save_marks();
+
+ // Apply "cur->do_oop" or "older->do_oop" to all the oops in objects
+ // allocated since the last call to save_marks in generations at or above
+ // "level" (including the permanent generation.) The "cur" closure is
+ // applied to references in the generation at "level", and the "older"
+ // closure to older (and permanent) generations.
+#define GCH_SINCE_SAVE_MARKS_ITERATE_DECL(OopClosureType, nv_suffix) \
+ void oop_since_save_marks_iterate(int level, \
+ OopClosureType* cur, \
+ OopClosureType* older);
+
+ ALL_SINCE_SAVE_MARKS_CLOSURES(GCH_SINCE_SAVE_MARKS_ITERATE_DECL)
+
+#undef GCH_SINCE_SAVE_MARKS_ITERATE_DECL
+
+ // Returns "true" iff no allocations have occurred in any generation at
+ // "level" or above (including the permanent generation) since the last
+ // call to "save_marks".
+ bool no_allocs_since_save_marks(int level);
+
+ // If a generation bails out of an incremental collection,
+ // it sets this flag.
+ bool incremental_collection_will_fail() {
+ return _incremental_collection_will_fail;
+ }
+ void set_incremental_collection_will_fail() {
+ _incremental_collection_will_fail = true;
+ }
+ void clear_incremental_collection_will_fail() {
+ _incremental_collection_will_fail = false;
+ }
+
+ bool last_incremental_collection_failed() const {
+ return _last_incremental_collection_failed;
+ }
+ void set_last_incremental_collection_failed() {
+ _last_incremental_collection_failed = true;
+ }
+ void clear_last_incremental_collection_failed() {
+ _last_incremental_collection_failed = false;
+ }
+
+ // Promotion of obj into gen failed. Try to promote obj to higher non-perm
+ // gens in ascending order; return the new location of obj if successful.
+ // Otherwise, try expand-and-allocate for obj in each generation starting at
+ // gen; return the new location of obj if successful. Otherwise, return NULL.
+ oop handle_failed_promotion(Generation* gen,
+ oop obj,
+ size_t obj_size,
+ oop* ref);
+
+private:
+ // Accessor for memory state verification support
+ NOT_PRODUCT(
+ static size_t skip_header_HeapWords() { return _skip_header_HeapWords; }
+ )
+
+ // Override
+ void check_for_non_bad_heap_word_value(HeapWord* addr,
+ size_t size) PRODUCT_RETURN;
+
+ // For use by mark-sweep. As implemented, mark-sweep-compact is global
+ // in an essential way: compaction is performed across generations, by
+ // iterating over spaces.
+ void prepare_for_compaction();
+
+ // Perform a full collection of the first max_level+1 generations.
+ // This is the low level interface used by the public versions of
+ // collect() and collect_locked(). Caller holds the Heap_lock on entry.
+ void collect_locked(GCCause::Cause cause, int max_level);
+
+ // Returns success or failure.
+ bool create_cms_collector();
+
+ // In support of ExplicitGCInvokesConcurrent functionality
+ bool should_do_concurrent_full_gc(GCCause::Cause cause);
+ void collect_mostly_concurrent(GCCause::Cause cause);
+
+protected:
+ virtual void gc_prologue(bool full);
+ virtual void gc_epilogue(bool full);
+
+public:
+ virtual void preload_and_dump(TRAPS) KERNEL_RETURN;
+};