J. Duke | 319a3b9 | 2007-12-01 00:00:00 +0000 | [diff] [blame^] | 1 | /* |
| 2 | * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
| 3 | * |
| 4 | * This code is free software; you can redistribute it and/or modify it |
| 5 | * under the terms of the GNU General Public License version 2 only, as |
| 6 | * published by the Free Software Foundation. |
| 7 | * |
| 8 | * This code is distributed in the hope that it will be useful, but WITHOUT |
| 9 | * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
| 10 | * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
| 11 | * version 2 for more details (a copy is included in the LICENSE file that |
| 12 | * accompanied this code). |
| 13 | * |
| 14 | * You should have received a copy of the GNU General Public License version |
| 15 | * 2 along with this work; if not, write to the Free Software Foundation, |
| 16 | * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
| 17 | * |
| 18 | * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, |
| 19 | * CA 95054 USA or visit www.sun.com if you need additional information or |
| 20 | * have any questions. |
| 21 | */ |
| 22 | |
| 23 | /* |
| 24 | * This file is available under and governed by the GNU General Public |
| 25 | * License version 2 only, as published by the Free Software Foundation. |
| 26 | * However, the following notice accompanied the original version of this |
| 27 | * file: |
| 28 | * |
| 29 | * Written by Doug Lea with assistance from members of JCP JSR-166 |
| 30 | * Expert Group and released to the public domain, as explained at |
| 31 | * http://creativecommons.org/licenses/publicdomain |
| 32 | */ |
| 33 | |
| 34 | /* |
| 35 | * @test |
| 36 | * @bug 4486658 |
| 37 | * @compile -source 1.5 SimpleReentrantLockLoops.java |
| 38 | * @run main/timeout=4500 SimpleReentrantLockLoops |
| 39 | * @summary multiple threads using a single lock |
| 40 | */ |
| 41 | |
| 42 | import java.util.concurrent.*; |
| 43 | import java.util.concurrent.locks.*; |
| 44 | import java.util.*; |
| 45 | |
| 46 | public final class SimpleReentrantLockLoops { |
| 47 | static final ExecutorService pool = Executors.newCachedThreadPool(); |
| 48 | static final LoopHelpers.SimpleRandom rng = new LoopHelpers.SimpleRandom(); |
| 49 | static boolean print = false; |
| 50 | static int iters = 1000000; |
| 51 | |
| 52 | public static void main(String[] args) throws Exception { |
| 53 | int maxThreads = 5; |
| 54 | if (args.length > 0) |
| 55 | maxThreads = Integer.parseInt(args[0]); |
| 56 | |
| 57 | print = true; |
| 58 | |
| 59 | int reps = 2; |
| 60 | for (int i = 1; i <= maxThreads; i += (i+1) >>> 1) { |
| 61 | int n = reps; |
| 62 | if (reps > 1) --reps; |
| 63 | while (n-- > 0) { |
| 64 | System.out.print("Threads: " + i); |
| 65 | new ReentrantLockLoop(i).test(); |
| 66 | Thread.sleep(100); |
| 67 | } |
| 68 | } |
| 69 | pool.shutdown(); |
| 70 | if (! pool.awaitTermination(Long.MAX_VALUE, TimeUnit.NANOSECONDS)) |
| 71 | throw new Error(); |
| 72 | } |
| 73 | |
| 74 | static final class ReentrantLockLoop implements Runnable { |
| 75 | private int v = rng.next(); |
| 76 | private volatile int result = 17; |
| 77 | private final ReentrantLock lock = new ReentrantLock(); |
| 78 | private final LoopHelpers.BarrierTimer timer = new LoopHelpers.BarrierTimer(); |
| 79 | private final CyclicBarrier barrier; |
| 80 | private final int nthreads; |
| 81 | ReentrantLockLoop(int nthreads) { |
| 82 | this.nthreads = nthreads; |
| 83 | barrier = new CyclicBarrier(nthreads+1, timer); |
| 84 | } |
| 85 | |
| 86 | final void test() throws Exception { |
| 87 | for (int i = 0; i < nthreads; ++i) |
| 88 | pool.execute(this); |
| 89 | barrier.await(); |
| 90 | barrier.await(); |
| 91 | if (print) { |
| 92 | long time = timer.getTime(); |
| 93 | long tpi = time / ((long)iters * nthreads); |
| 94 | System.out.print("\t" + LoopHelpers.rightJustify(tpi) + " ns per lock"); |
| 95 | double secs = (double)(time) / 1000000000.0; |
| 96 | System.out.println("\t " + secs + "s run time"); |
| 97 | } |
| 98 | |
| 99 | int r = result; |
| 100 | if (r == 0) // avoid overoptimization |
| 101 | System.out.println("useless result: " + r); |
| 102 | } |
| 103 | |
| 104 | public final void run() { |
| 105 | try { |
| 106 | barrier.await(); |
| 107 | int sum = v; |
| 108 | int x = 0; |
| 109 | int n = iters; |
| 110 | do { |
| 111 | lock.lock(); |
| 112 | try { |
| 113 | if ((n & 255) == 0) |
| 114 | v = x = LoopHelpers.compute2(LoopHelpers.compute1(v)); |
| 115 | else |
| 116 | v = x += ~(v - n); |
| 117 | } |
| 118 | finally { |
| 119 | lock.unlock(); |
| 120 | } |
| 121 | // Once in a while, do something more expensive |
| 122 | if ((~n & 255) == 0) { |
| 123 | sum += LoopHelpers.compute1(LoopHelpers.compute2(x)); |
| 124 | } |
| 125 | else |
| 126 | sum += sum ^ x; |
| 127 | } while (n-- > 0); |
| 128 | barrier.await(); |
| 129 | result += sum; |
| 130 | } |
| 131 | catch (Exception ie) { |
| 132 | return; |
| 133 | } |
| 134 | } |
| 135 | } |
| 136 | |
| 137 | } |