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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  19  * or visit www.oracle.com if you need additional information or have any
  20  * 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/publicdomain/zero/1.0/
  32  */
  33 
  34 /*
  35  * @test
  36  * @bug 4486658 5031862
  37  * @run main TimeoutLockLoops
  38  * @key intermittent
  39  * @summary Checks for responsiveness of locks to timeouts.
  40  * Runs under the assumption that ITERS computations require more than
  41  * TIMEOUT msecs to complete, which seems to be a safe assumption for
  42  * another decade.
  43  */
  44 
  45 import java.util.concurrent.*;
  46 import java.util.concurrent.locks.*;
  47 import java.util.*;
  48 
  49 public final class TimeoutLockLoops {
  50     static final ExecutorService pool = Executors.newCachedThreadPool();
  51     static final LoopHelpers.SimpleRandom rng = new LoopHelpers.SimpleRandom();
  52     static boolean print = false;
  53     static final int ITERS = Integer.MAX_VALUE;
  54     static final long TIMEOUT = 100;
  55 
  56     public static void main(String[] args) throws Exception {
  57         int maxThreads = 100;
  58         if (args.length > 0)
  59             maxThreads = Integer.parseInt(args[0]);
  60 
  61 
  62         print = true;
  63 
  64         for (int i = 1; i <= maxThreads; i += (i+1) >>> 1) {
  65             System.out.print("Threads: " + i);
  66             new ReentrantLockLoop(i).test();
  67             Thread.sleep(10);
  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 boolean completed;
  77         private volatile int result = 17;
  78         private final ReentrantLock lock = new ReentrantLock();
  79         private final LoopHelpers.BarrierTimer timer = new LoopHelpers.BarrierTimer();
  80         private final CyclicBarrier barrier;
  81         private final int nthreads;
  82         ReentrantLockLoop(int nthreads) {
  83             this.nthreads = nthreads;
  84             barrier = new CyclicBarrier(nthreads+1, timer);
  85         }
  86 
  87         final void test() throws Exception {
  88             for (int i = 0; i < nthreads; ++i) {
  89                 lock.lock();
  90                 pool.execute(this);
  91                 lock.unlock();
  92             }
  93             barrier.await();
  94             Thread.sleep(TIMEOUT);
  95             while (!lock.tryLock()); // Jam lock
  96             //            lock.lock();
  97             barrier.await();
  98             if (print) {
  99                 long time = timer.getTime();
 100                 double secs = (double)(time) / 1000000000.0;
 101                 System.out.println("\t " + secs + "s run time");
 102             }
 103 
 104             if (completed)
 105                 throw new Error("Some thread completed instead of timing out");
 106             int r = result;
 107             if (r == 0) // avoid overoptimization
 108                 System.out.println("useless result: " + r);
 109         }
 110 
 111         public final void run() {
 112             try {
 113                 barrier.await();
 114                 int sum = v;
 115                 int x = 17;
 116                 int n = ITERS;
 117                 final ReentrantLock lock = this.lock;
 118                 for (;;) {
 119                     if (x != 0) {
 120                         if (n-- <= 0)
 121                             break;
 122                     }
 123                     if (!lock.tryLock(TIMEOUT, TimeUnit.MILLISECONDS))
 124                         break;
 125                     try {
 126                         v = x = LoopHelpers.compute1(v);
 127                     }
 128                     finally {
 129                         lock.unlock();
 130                     }
 131                     sum += LoopHelpers.compute2(x);
 132                 }
 133                 if (n <= 0)
 134                     completed = true;
 135                 barrier.await();
 136                 result += sum;
 137             }
 138             catch (Exception ex) {
 139                 ex.printStackTrace();
 140                 return;
 141             }
 142         }
 143     }
 144 
 145 
 146 }
--- EOF ---