20192
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1 /*
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2 * Copyright (c) 2014, Oracle and/or its affiliates. All rights reserved.
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3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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4 *
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5 * This code is free software; you can redistribute it and/or modify it
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6 * under the terms of the GNU General Public License version 2 only, as
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7 * published by the Free Software Foundation.
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8 *
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9 * This code is distributed in the hope that it will be useful, but WITHOUT
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10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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12 * version 2 for more details (a copy is included in the LICENSE file that
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13 * accompanied this code).
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14 *
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15 * You should have received a copy of the GNU General Public License version
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16 * 2 along with this work; if not, write to the Free Software Foundation,
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17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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18 *
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19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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20 * or visit www.oracle.com if you need additional information or have any
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21 * questions.
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22 *
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23 */
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24
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25 #include "precompiled.hpp"
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26 #include "gc_implementation/shared/suspendibleThreadSet.hpp"
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27 #include "runtime/mutexLocker.hpp"
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28 #include "runtime/thread.inline.hpp"
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29
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30 uint SuspendibleThreadSet::_nthreads = 0;
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31 uint SuspendibleThreadSet::_nthreads_stopped = 0;
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32 bool SuspendibleThreadSet::_suspend_all = false;
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33 double SuspendibleThreadSet::_suspend_all_start = 0.0;
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34
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35 void SuspendibleThreadSet::join() {
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36 MonitorLockerEx ml(STS_lock, Mutex::_no_safepoint_check_flag);
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37 while (_suspend_all) {
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38 ml.wait(Mutex::_no_safepoint_check_flag);
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39 }
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40 _nthreads++;
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41 }
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42
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43 void SuspendibleThreadSet::leave() {
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44 MonitorLockerEx ml(STS_lock, Mutex::_no_safepoint_check_flag);
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45 assert(_nthreads > 0, "Invalid");
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46 _nthreads--;
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47 if (_suspend_all) {
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48 ml.notify_all();
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49 }
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50 }
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51
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52 void SuspendibleThreadSet::yield() {
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53 if (_suspend_all) {
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54 MonitorLockerEx ml(STS_lock, Mutex::_no_safepoint_check_flag);
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55 if (_suspend_all) {
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56 _nthreads_stopped++;
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57 if (_nthreads_stopped == _nthreads) {
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58 if (ConcGCYieldTimeout > 0) {
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59 double now = os::elapsedTime();
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60 guarantee((now - _suspend_all_start) * 1000.0 < (double)ConcGCYieldTimeout, "Long delay");
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61 }
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62 }
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63 ml.notify_all();
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64 while (_suspend_all) {
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65 ml.wait(Mutex::_no_safepoint_check_flag);
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66 }
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67 assert(_nthreads_stopped > 0, "Invalid");
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68 _nthreads_stopped--;
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69 ml.notify_all();
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70 }
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71 }
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72 }
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73
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74 void SuspendibleThreadSet::synchronize() {
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75 assert(Thread::current()->is_VM_thread(), "Must be the VM thread");
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76 if (ConcGCYieldTimeout > 0) {
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77 _suspend_all_start = os::elapsedTime();
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78 }
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79 MonitorLockerEx ml(STS_lock, Mutex::_no_safepoint_check_flag);
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80 assert(!_suspend_all, "Only one at a time");
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81 _suspend_all = true;
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82 while (_nthreads_stopped < _nthreads) {
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83 ml.wait(Mutex::_no_safepoint_check_flag);
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84 }
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85 }
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86
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87 void SuspendibleThreadSet::desynchronize() {
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88 assert(Thread::current()->is_VM_thread(), "Must be the VM thread");
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89 MonitorLockerEx ml(STS_lock, Mutex::_no_safepoint_check_flag);
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90 assert(_nthreads_stopped == _nthreads, "Invalid");
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91 _suspend_all = false;
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92 ml.notify_all();
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93 }
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