Fri, 01 Oct 2010 16:43:05 -0400
6980838: G1: guarantee(false) failed: thread has an unexpected active value in its SATB queue
Summary: Under certain circumstances a safepoint could happen between a JavaThread object being created and that object being added to the Java threads list. This could cause the active field of that thread's SATB queue to get out-of-sync with respect to the other Java threads. The solution is to activate the SATB queue, when necessary, before adding the thread to the Java threads list, not when the JavaThread object is created. The changeset also includes a small fix to rename the surrogate locker thread from "Surrogate Locker Thread (CMS)" to "Surrogate Locker Thread (Concurrent GC)" since it's also used in G1.
Reviewed-by: iveresov, ysr, johnc, jcoomes
1 /*
2 * Copyright (c) 2001, 2010, Oracle and/or its affiliates. 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
25 class FreeIdSet;
27 // A closure class for processing card table entries. Note that we don't
28 // require these closure objects to be stack-allocated.
29 class CardTableEntryClosure: public CHeapObj {
30 public:
31 // Process the card whose card table entry is "card_ptr". If returns
32 // "false", terminate the iteration early.
33 virtual bool do_card_ptr(jbyte* card_ptr, int worker_i = 0) = 0;
34 };
36 // A ptrQueue whose elements are "oops", pointers to object heads.
37 class DirtyCardQueue: public PtrQueue {
38 public:
39 DirtyCardQueue(PtrQueueSet* qset_, bool perm = false) :
40 // Dirty card queues are always active, so we create them with their
41 // active field set to true.
42 PtrQueue(qset_, perm, true /* active */) { }
44 // Apply the closure to all elements, and reset the index to make the
45 // buffer empty. If a closure application returns "false", return
46 // "false" immediately, halting the iteration. If "consume" is true,
47 // deletes processed entries from logs.
48 bool apply_closure(CardTableEntryClosure* cl,
49 bool consume = true,
50 size_t worker_i = 0);
52 // Apply the closure to all elements of "buf", down to "index"
53 // (inclusive.) If returns "false", then a closure application returned
54 // "false", and we return immediately. If "consume" is true, entries are
55 // set to NULL as they are processed, so they will not be processed again
56 // later.
57 static bool apply_closure_to_buffer(CardTableEntryClosure* cl,
58 void** buf, size_t index, size_t sz,
59 bool consume = true,
60 int worker_i = 0);
61 void **get_buf() { return _buf;}
62 void set_buf(void **buf) {_buf = buf;}
63 size_t get_index() { return _index;}
64 void reinitialize() { _buf = 0; _sz = 0; _index = 0;}
65 };
69 class DirtyCardQueueSet: public PtrQueueSet {
70 CardTableEntryClosure* _closure;
72 DirtyCardQueue _shared_dirty_card_queue;
74 // Override.
75 bool mut_process_buffer(void** buf);
77 // Protected by the _cbl_mon.
78 FreeIdSet* _free_ids;
80 // The number of completed buffers processed by mutator and rs thread,
81 // respectively.
82 jint _processed_buffers_mut;
83 jint _processed_buffers_rs_thread;
85 public:
86 DirtyCardQueueSet(bool notify_when_complete = true);
88 void initialize(Monitor* cbl_mon, Mutex* fl_lock,
89 int process_completed_threshold,
90 int max_completed_queue,
91 Mutex* lock, PtrQueueSet* fl_owner = NULL);
93 // The number of parallel ids that can be claimed to allow collector or
94 // mutator threads to do card-processing work.
95 static size_t num_par_ids();
97 static void handle_zero_index_for_thread(JavaThread* t);
99 // Register "blk" as "the closure" for all queues. Only one such closure
100 // is allowed. The "apply_closure_to_completed_buffer" method will apply
101 // this closure to a completed buffer, and "iterate_closure_all_threads"
102 // applies it to partially-filled buffers (the latter should only be done
103 // with the world stopped).
104 void set_closure(CardTableEntryClosure* closure);
106 // If there is a registered closure for buffers, apply it to all entries
107 // in all currently-active buffers. This should only be applied at a
108 // safepoint. (Currently must not be called in parallel; this should
109 // change in the future.) If "consume" is true, processed entries are
110 // discarded.
111 void iterate_closure_all_threads(bool consume = true,
112 size_t worker_i = 0);
114 // If there exists some completed buffer, pop it, then apply the
115 // registered closure to all its elements, nulling out those elements
116 // processed. If all elements are processed, returns "true". If no
117 // completed buffers exist, returns false. If a completed buffer exists,
118 // but is only partially completed before a "yield" happens, the
119 // partially completed buffer (with its processed elements set to NULL)
120 // is returned to the completed buffer set, and this call returns false.
121 bool apply_closure_to_completed_buffer(int worker_i = 0,
122 int stop_at = 0,
123 bool during_pause = false);
125 // If there exists some completed buffer, pop it, then apply the
126 // specified closure to all its elements, nulling out those elements
127 // processed. If all elements are processed, returns "true". If no
128 // completed buffers exist, returns false. If a completed buffer exists,
129 // but is only partially completed before a "yield" happens, the
130 // partially completed buffer (with its processed elements set to NULL)
131 // is returned to the completed buffer set, and this call returns false.
132 bool apply_closure_to_completed_buffer(CardTableEntryClosure* cl,
133 int worker_i = 0,
134 int stop_at = 0,
135 bool during_pause = false);
137 // Helper routine for the above.
138 bool apply_closure_to_completed_buffer_helper(CardTableEntryClosure* cl,
139 int worker_i,
140 BufferNode* nd);
142 BufferNode* get_completed_buffer(int stop_at);
144 // Applies the current closure to all completed buffers,
145 // non-consumptively.
146 void apply_closure_to_all_completed_buffers();
148 DirtyCardQueue* shared_dirty_card_queue() {
149 return &_shared_dirty_card_queue;
150 }
152 // Deallocate any completed log buffers
153 void clear();
155 // If a full collection is happening, reset partial logs, and ignore
156 // completed ones: the full collection will make them all irrelevant.
157 void abandon_logs();
159 // If any threads have partial logs, add them to the global list of logs.
160 void concatenate_logs();
161 void clear_n_completed_buffers() { _n_completed_buffers = 0;}
163 jint processed_buffers_mut() {
164 return _processed_buffers_mut;
165 }
166 jint processed_buffers_rs_thread() {
167 return _processed_buffers_rs_thread;
168 }
170 };