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  * @summary Checks for responsiveness of locks to timeouts.
  39  * Runs under the assumption that ITERS computations require more than
  40  * TIMEOUT msecs to complete, which seems to be a safe assumption for
  41  * another decade.
  42  */
  43 
  44 import java.util.concurrent.*;
  45 import java.util.concurrent.locks.*;
  46 import java.util.*;
  47 
  48 public final class TimeoutLockLoops {
  49     static final ExecutorService pool = Executors.newCachedThreadPool();
  50     static final LoopHelpers.SimpleRandom rng = new LoopHelpers.SimpleRandom();
  51     static boolean print = false;
  52     static final int ITERS = Integer.MAX_VALUE;
  53     static final long TIMEOUT = 100;
  54 
  55     public static void main(String[] args) throws Exception {
  56         int maxThreads = 100;
  57         if (args.length > 0)
  58             maxThreads = Integer.parseInt(args[0]);
  59 
  60 
  61         print = true;
  62 
  63         for (int i = 1; i <= maxThreads; i += (i+1) >>> 1) {
  64             System.out.print("Threads: " + i);
  65             new ReentrantLockLoop(i).test();
  66             Thread.sleep(10);
  67         }
  68         pool.shutdown();
  69         if (! pool.awaitTermination(Long.MAX_VALUE, TimeUnit.NANOSECONDS))
  70             throw new Error();
  71     }
  72 
  73     static final class ReentrantLockLoop implements Runnable {
  74         private int v = rng.next();
  75         private volatile boolean completed;
  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                 lock.lock();
  89                 pool.execute(this);
  90                 lock.unlock();
  91             }
  92             barrier.await();
  93             Thread.sleep(TIMEOUT);
  94             while (!lock.tryLock()); // Jam lock
  95             //            lock.lock();
  96             barrier.await();
  97             if (print) {
  98                 long time = timer.getTime();
  99                 double secs = (double)(time) / 1000000000.0;
 100                 System.out.println("\t " + secs + "s run time");
 101             }
 102 
 103             if (completed)
 104                 throw new Error("Some thread completed instead of timing out");
 105             int r = result;
 106             if (r == 0) // avoid overoptimization
 107                 System.out.println("useless result: " + r);
 108         }
 109 
 110         public final void run() {
 111             try {
 112                 barrier.await();
 113                 int sum = v;
 114                 int x = 17;
 115                 int n = ITERS;
 116                 final ReentrantLock lock = this.lock;
 117                 for (;;) {
 118                     if (x != 0) {
 119                         if (n-- <= 0)
 120                             break;
 121                     }
 122                     if (!lock.tryLock(TIMEOUT, TimeUnit.MILLISECONDS))
 123                         break;
 124                     try {
 125                         v = x = LoopHelpers.compute1(v);
 126                     }
 127                     finally {
 128                         lock.unlock();
 129                     }
 130                     sum += LoopHelpers.compute2(x);
 131                 }
 132                 if (n <= 0)
 133                     completed = true;
 134                 barrier.await();
 135                 result += sum;
 136             }
 137             catch (Exception ex) {
 138                 ex.printStackTrace();
 139                 return;
 140             }
 141         }
 142     }
 143 
 144 
 145 }
--- EOF ---