test/loops/TimeoutMutexLoops.java

/*
 * Written by Doug Lea with assistance from members of JCP JSR-166
 * Expert Group and released to the public domain, as explained at
 * http://creativecommons.org/publicdomain/zero/1.0/
 */
/*
 * @test
 * Checks for responsiveness of locks to timeouts. Runs under the
 * assumption that ITERS computations require more than TIMEOUT msecs
 * to complete, which seems to be a safe assumption for another
 * decade.
 */

import java.util.concurrent.*;
import java.util.concurrent.locks.*;
import java.util.*;

public final class TimeoutMutexLoops {
    static final ExecutorService pool = Executors.newCachedThreadPool();
    static final LoopHelpers.SimpleRandom rng = new LoopHelpers.SimpleRandom();
    static boolean print = false;
    static final int ITERS = Integer.MAX_VALUE;
    static final long TIMEOUT = 100;

    public static void main(String[] args) throws Exception {
        int maxThreads = 100;
        if (args.length > 0)
            maxThreads = Integer.parseInt(args[0]);

        print = true;

        for (int i = 1; i <= maxThreads; i += (i+1) >>> 1) {
            System.out.print("Threads: " + i);
            new MutexLoop(i).test();
            Thread.sleep(TIMEOUT);
        }
        pool.shutdown();
    }

    static final class MutexLoop implements Runnable {
        private int v = rng.next();
        private volatile boolean completed;
        private volatile int result = 17;
        private final Mutex lock = new Mutex();
        private final LoopHelpers.BarrierTimer timer = new LoopHelpers.BarrierTimer();
        private final CyclicBarrier barrier;
        private final int nthreads;
        MutexLoop(int nthreads) {
            this.nthreads = nthreads;
            barrier = new CyclicBarrier(nthreads+1, timer);
        }

        final void test() throws Exception {
            for (int i = 0; i < nthreads; ++i)
                pool.execute(this);
            barrier.await();
            Thread.sleep(TIMEOUT);
            lock.lock();
            barrier.await();
            if (print) {
                long time = timer.getTime();
                double secs = (double) time / 1000000000.0;
                System.out.println("\t " + secs + "s run time");
            }

            if (completed)
                throw new Error("Some thread completed instead of timing out");
            int r = result;
            if (r == 0) // avoid overoptimization
                System.out.println("useless result: " + r);
        }

        public final void run() {
            try {
                barrier.await();
                int sum = v;
                int x = 0;
                int n = ITERS;
                do {
                    if (!lock.tryLock(TIMEOUT, TimeUnit.MILLISECONDS))
                        break;
                    try {
                        v = x = LoopHelpers.compute1(v);
                    }
                    finally {
                        lock.unlock();
                    }
                    sum += LoopHelpers.compute2(x);
                } while (n-- > 0);
                if (n <= 0)
                    completed = true;
                barrier.await();
                result += sum;
            }
            catch (Exception ie) {
                return;
            }
        }
    }

}
Revision:	1.5
Committed:	Tue Mar 15 19:47:06 2011 UTC (13 years, 2 months ago) by jsr166
Branch:	MAIN
CVS Tags:	release-1_7_0
Changes since 1.4:	+1 -1 lines
Log Message:	Update Creative Commons license URL in legal notices
#	User	Rev	Content
1	dl	1.1	/*
2	dl	1.2	* Written by Doug Lea with assistance from members of JCP JSR-166
3			* Expert Group and released to the public domain, as explained at
4	jsr166	1.5	* http://creativecommons.org/publicdomain/zero/1.0/
5	dl	1.2	*/
6			/*
7	dl	1.1	* @test
8			* Checks for responsiveness of locks to timeouts. Runs under the
9			* assumption that ITERS computations require more than TIMEOUT msecs
10			* to complete, which seems to be a safe assumption for another
11			* decade.
12			*/
13
14			import java.util.concurrent.*;
15			import java.util.concurrent.locks.*;
16			import java.util.*;
17
18			public final class TimeoutMutexLoops {
19			static final ExecutorService pool = Executors.newCachedThreadPool();
20			static final LoopHelpers.SimpleRandom rng = new LoopHelpers.SimpleRandom();
21			static boolean print = false;
22			static final int ITERS = Integer.MAX_VALUE;
23	jsr166	1.3	static final long TIMEOUT = 100;
24	dl	1.1
25			public static void main(String[] args) throws Exception {
26			int maxThreads = 100;
27	jsr166	1.3	if (args.length > 0)
28	dl	1.1	maxThreads = Integer.parseInt(args[0]);
29
30			print = true;
31
32			for (int i = 1; i <= maxThreads; i += (i+1) >>> 1) {
33			System.out.print("Threads: " + i);
34			new MutexLoop(i).test();
35			Thread.sleep(TIMEOUT);
36			}
37			pool.shutdown();
38			}
39
40			static final class MutexLoop implements Runnable {
41			private int v = rng.next();
42			private volatile boolean completed;
43			private volatile int result = 17;
44			private final Mutex lock = new Mutex();
45			private final LoopHelpers.BarrierTimer timer = new LoopHelpers.BarrierTimer();
46			private final CyclicBarrier barrier;
47			private final int nthreads;
48			MutexLoop(int nthreads) {
49			this.nthreads = nthreads;
50			barrier = new CyclicBarrier(nthreads+1, timer);
51			}
52
53			final void test() throws Exception {
54	jsr166	1.3	for (int i = 0; i < nthreads; ++i)
55	dl	1.1	pool.execute(this);
56			barrier.await();
57			Thread.sleep(TIMEOUT);
58			lock.lock();
59			barrier.await();
60			if (print) {
61			long time = timer.getTime();
62	jsr166	1.4	double secs = (double) time / 1000000000.0;
63	dl	1.1	System.out.println("\t " + secs + "s run time");
64			}
65
66			if (completed)
67			throw new Error("Some thread completed instead of timing out");
68			int r = result;
69			if (r == 0) // avoid overoptimization
70			System.out.println("useless result: " + r);
71			}
72
73			public final void run() {
74			try {
75	jsr166	1.3	barrier.await();
76	dl	1.1	int sum = v;
77			int x = 0;
78			int n = ITERS;
79			do {
80			if (!lock.tryLock(TIMEOUT, TimeUnit.MILLISECONDS))
81			break;
82			try {
83			v = x = LoopHelpers.compute1(v);
84			}
85			finally {
86			lock.unlock();
87			}
88			sum += LoopHelpers.compute2(x);
89			} while (n-- > 0);
90			if (n <= 0)
91			completed = true;
92			barrier.await();
93			result += sum;
94			}
95	jsr166	1.3	catch (Exception ie) {
96			return;
97	dl	1.1	}
98			}
99			}
100
101			}