Tue, 13 Apr 2010 13:52:10 -0700
6858496: Clear all SoftReferences before an out-of-memory due to GC overhead limit.
Summary: Ensure a full GC that clears SoftReferences before throwing an out-of-memory
Reviewed-by: ysr, jcoomes
1 /*
2 * Copyright 2001-2007 Sun Microsystems, Inc. All Rights Reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
20 * CA 95054 USA or visit www.sun.com if you need additional information or
21 * have any questions.
22 *
23 */
25 class ObjectClosure;
26 class JavaThread;
28 // A ptrQueue whose elements are "oops", pointers to object heads.
29 class ObjPtrQueue: public PtrQueue {
30 public:
31 ObjPtrQueue(PtrQueueSet* qset_, bool perm = false) :
32 PtrQueue(qset_, perm, qset_->is_active()) { }
33 // Apply the closure to all elements, and reset the index to make the
34 // buffer empty.
35 void apply_closure(ObjectClosure* cl);
37 // Apply the closure to all elements of "buf", down to "index" (inclusive.)
38 static void apply_closure_to_buffer(ObjectClosure* cl,
39 void** buf, size_t index, size_t sz);
41 void verify_oops_in_buffer() NOT_DEBUG_RETURN;
42 };
46 class SATBMarkQueueSet: public PtrQueueSet {
47 ObjectClosure* _closure;
48 ObjectClosure** _par_closures; // One per ParGCThread.
50 ObjPtrQueue _shared_satb_queue;
52 // Utility function to support sequential and parallel versions. If
53 // "par" is true, then "worker" is the par thread id; if "false", worker
54 // is ignored.
55 bool apply_closure_to_completed_buffer_work(bool par, int worker);
57 #ifdef ASSERT
58 void dump_active_values(JavaThread* first, bool expected_active);
59 #endif // ASSERT
61 public:
62 SATBMarkQueueSet();
64 void initialize(Monitor* cbl_mon, Mutex* fl_lock,
65 int process_completed_threshold,
66 Mutex* lock);
68 static void handle_zero_index_for_thread(JavaThread* t);
70 // Apply "set_active(b)" to all Java threads' SATB queues. It should be
71 // called only with the world stopped. The method will assert that the
72 // SATB queues of all threads it visits, as well as the SATB queue
73 // set itself, has an active value same as expected_active.
74 void set_active_all_threads(bool b, bool expected_active);
76 // Register "blk" as "the closure" for all queues. Only one such closure
77 // is allowed. The "apply_closure_to_completed_buffer" method will apply
78 // this closure to a completed buffer, and "iterate_closure_all_threads"
79 // applies it to partially-filled buffers (the latter should only be done
80 // with the world stopped).
81 void set_closure(ObjectClosure* closure);
82 // Set the parallel closures: pointer is an array of pointers to
83 // closures, one for each parallel GC thread.
84 void set_par_closure(int i, ObjectClosure* closure);
86 // If there is a registered closure for buffers, apply it to all entries
87 // in all currently-active buffers. This should only be applied at a
88 // safepoint. (Currently must not be called in parallel; this should
89 // change in the future.)
90 void iterate_closure_all_threads();
91 // Parallel version of the above.
92 void par_iterate_closure_all_threads(int worker);
94 // If there exists some completed buffer, pop it, then apply the
95 // registered closure to all its elements, and return true. If no
96 // completed buffers exist, return false.
97 bool apply_closure_to_completed_buffer() {
98 return apply_closure_to_completed_buffer_work(false, 0);
99 }
100 // Parallel version of the above.
101 bool par_apply_closure_to_completed_buffer(int worker) {
102 return apply_closure_to_completed_buffer_work(true, worker);
103 }
105 ObjPtrQueue* shared_satb_queue() { return &_shared_satb_queue; }
107 // If a marking is being abandoned, reset any unprocessed log buffers.
108 void abandon_partial_marking();
110 };