test/loops/LockOncePerThreadLoops.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/
 */

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

public final class LockOncePerThreadLoops {
    static final ExecutorService pool = Executors.newCachedThreadPool();
    static final LoopHelpers.SimpleRandom rng = new LoopHelpers.SimpleRandom();
    static boolean print = false;
    static int nlocks = 500000;
    static int nthreads = 100;
    static int replications = 20;

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

        if (args.length > 1)
            nlocks = Integer.parseInt(args[1]);

        print = true;

        for (int i = 0; i < replications; ++i) {
            System.out.print("Iteration: " + i);
            new ReentrantLockLoop().test();
            Thread.sleep(100);
        }
        pool.shutdown();
    }

    static final class ReentrantLockLoop implements Runnable {
        private int v = rng.next();
        private volatile int result = 17;
        final ReentrantLock[]locks = new ReentrantLock[nlocks];

        private final ReentrantLock lock = new ReentrantLock();
        private final LoopHelpers.BarrierTimer timer = new LoopHelpers.BarrierTimer();
        private final CyclicBarrier barrier;
        ReentrantLockLoop() {
            barrier = new CyclicBarrier(nthreads+1, timer);
            for (int i = 0; i < nlocks; ++i)
                locks[i] = new ReentrantLock();
        }

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

            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;
                for (int i = 0; i < locks.length; ++i) {
                    locks[i].lock();
                    try {
                            v = x += ~(v - i);
                    }
                    finally {
                        locks[i].unlock();
                    }
                    // Once in a while, do something more expensive
                    if ((~i & 255) == 0) {
                        sum += LoopHelpers.compute1(LoopHelpers.compute2(x));
                    }
                    else
                        sum += sum ^ x;
                }
                barrier.await();
                result += sum;
            }
            catch (Exception ie) {
                return;
            }
        }
    }

}
Revision:	1.5
Committed:	Tue Mar 15 19:47:05 2011 UTC (13 years, 1 month 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			* Written by Doug Lea with assistance from members of JCP JSR-166
3	dl	1.2	* Expert Group and released to the public domain, as explained at
4	jsr166	1.5	* http://creativecommons.org/publicdomain/zero/1.0/
5	dl	1.1	*/
6
7			import java.util.concurrent.*;
8			import java.util.concurrent.locks.*;
9			import java.util.*;
10
11			public final class LockOncePerThreadLoops {
12			static final ExecutorService pool = Executors.newCachedThreadPool();
13			static final LoopHelpers.SimpleRandom rng = new LoopHelpers.SimpleRandom();
14			static boolean print = false;
15			static int nlocks = 500000;
16			static int nthreads = 100;
17			static int replications = 20;
18
19			public static void main(String[] args) throws Exception {
20	jsr166	1.3	if (args.length > 0)
21	dl	1.1	replications = Integer.parseInt(args[0]);
22
23	jsr166	1.3	if (args.length > 1)
24	dl	1.1	nlocks = Integer.parseInt(args[1]);
25
26			print = true;
27
28			for (int i = 0; i < replications; ++i) {
29			System.out.print("Iteration: " + i);
30			new ReentrantLockLoop().test();
31			Thread.sleep(100);
32			}
33			pool.shutdown();
34			}
35
36			static final class ReentrantLockLoop implements Runnable {
37			private int v = rng.next();
38			private volatile int result = 17;
39			final ReentrantLock[]locks = new ReentrantLock[nlocks];
40
41			private final ReentrantLock lock = new ReentrantLock();
42			private final LoopHelpers.BarrierTimer timer = new LoopHelpers.BarrierTimer();
43			private final CyclicBarrier barrier;
44			ReentrantLockLoop() {
45			barrier = new CyclicBarrier(nthreads+1, timer);
46			for (int i = 0; i < nlocks; ++i)
47			locks[i] = new ReentrantLock();
48			}
49
50			final void test() throws Exception {
51	jsr166	1.3	for (int i = 0; i < nthreads; ++i)
52	dl	1.1	pool.execute(this);
53			barrier.await();
54			barrier.await();
55			if (print) {
56			long time = timer.getTime();
57	jsr166	1.4	double secs = (double) time / 1000000000.0;
58	dl	1.1	System.out.println("\t " + secs + "s run time");
59			}
60
61			int r = result;
62			if (r == 0) // avoid overoptimization
63			System.out.println("useless result: " + r);
64			}
65
66			public final void run() {
67			try {
68	jsr166	1.3	barrier.await();
69	dl	1.1	int sum = v;
70			int x = 0;
71			for (int i = 0; i < locks.length; ++i) {
72			locks[i].lock();
73			try {
74			v = x += ~(v - i);
75			}
76			finally {
77			locks[i].unlock();
78			}
79			// Once in a while, do something more expensive
80			if ((~i & 255) == 0) {
81			sum += LoopHelpers.compute1(LoopHelpers.compute2(x));
82			}
83			else
84			sum += sum ^ x;
85			}
86			barrier.await();
87			result += sum;
88			}
89	jsr166	1.3	catch (Exception ie) {
90			return;
91	dl	1.1	}
92			}
93			}
94
95			}