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.CyclicBarrier;
import java.util.concurrent.BlockingQueue;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.TimeUnit;

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:	1.7
Committed:	Sat Dec 31 19:25:33 2016 UTC (7 years, 4 months ago) by jsr166
Branch:	MAIN
Changes since 1.6:	+5 -3 lines
Log Message:	organize imports
#	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	jsr166	1.7	import java.util.concurrent.CyclicBarrier;
15			import java.util.concurrent.BlockingQueue;
16			import java.util.concurrent.ExecutorService;
17			import java.util.concurrent.Executors;
18			import java.util.concurrent.TimeUnit;
19	dl	1.1
20			public final class TimeoutMutexLoops {
21			static final ExecutorService pool = Executors.newCachedThreadPool();
22			static final LoopHelpers.SimpleRandom rng = new LoopHelpers.SimpleRandom();
23			static boolean print = false;
24			static final int ITERS = Integer.MAX_VALUE;
25	jsr166	1.3	static final long TIMEOUT = 100;
26	dl	1.1
27			public static void main(String[] args) throws Exception {
28			int maxThreads = 100;
29	jsr166	1.3	if (args.length > 0)
30	dl	1.1	maxThreads = Integer.parseInt(args[0]);
31
32			print = true;
33
34			for (int i = 1; i <= maxThreads; i += (i+1) >>> 1) {
35			System.out.print("Threads: " + i);
36			new MutexLoop(i).test();
37			Thread.sleep(TIMEOUT);
38			}
39			pool.shutdown();
40			}
41
42			static final class MutexLoop implements Runnable {
43			private int v = rng.next();
44			private volatile boolean completed;
45			private volatile int result = 17;
46			private final Mutex lock = new Mutex();
47			private final LoopHelpers.BarrierTimer timer = new LoopHelpers.BarrierTimer();
48			private final CyclicBarrier barrier;
49			private final int nthreads;
50			MutexLoop(int nthreads) {
51			this.nthreads = nthreads;
52			barrier = new CyclicBarrier(nthreads+1, timer);
53			}
54
55			final void test() throws Exception {
56	jsr166	1.3	for (int i = 0; i < nthreads; ++i)
57	dl	1.1	pool.execute(this);
58			barrier.await();
59			Thread.sleep(TIMEOUT);
60			lock.lock();
61			barrier.await();
62			if (print) {
63			long time = timer.getTime();
64	jsr166	1.4	double secs = (double) time / 1000000000.0;
65	dl	1.1	System.out.println("\t " + secs + "s run time");
66			}
67
68			if (completed)
69			throw new Error("Some thread completed instead of timing out");
70			int r = result;
71			if (r == 0) // avoid overoptimization
72			System.out.println("useless result: " + r);
73			}
74
75			public final void run() {
76			try {
77	jsr166	1.3	barrier.await();
78	dl	1.1	int sum = v;
79			int x = 0;
80			int n = ITERS;
81			do {
82			if (!lock.tryLock(TIMEOUT, TimeUnit.MILLISECONDS))
83			break;
84			try {
85			v = x = LoopHelpers.compute1(v);
86			}
87			finally {
88			lock.unlock();
89			}
90			sum += LoopHelpers.compute2(x);
91			} while (n-- > 0);
92			if (n <= 0)
93			completed = true;
94			barrier.await();
95			result += sum;
96			}
97	jsr166	1.3	catch (Exception ie) {
98			return;
99	dl	1.1	}
100			}
101			}
102
103			}