test/loops/NoopLockLoops.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/licenses/publicdomain
 */

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

public final class NoopLockLoops {
    static final ExecutorService pool = Executors.newCachedThreadPool();
    static final LoopHelpers.SimpleRandom rng = new LoopHelpers.SimpleRandom();
    static boolean print = false;
    static int iters = 20000000;

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

        new ReentrantLockLoop(1).test();
        new ReentrantLockLoop(1).test();
        print = true;

        int k = 1;
        for (int i = 1; i <= maxThreads;) {
            System.out.print("Threads: " + i);
            new ReentrantLockLoop(i).test();
            Thread.sleep(100);
            if (i == k) {
                k = i << 1;
                i = i + (i >>> 1);
            }
            else
                i = k;
        }
        pool.shutdown();
    }

    static final class ReentrantLockLoop implements Runnable {
        private int v = rng.next();
        private volatile int result = 17;
        private final LoopHelpers.BarrierTimer timer = new LoopHelpers.BarrierTimer();
        private final CyclicBarrier barrier;
        private final int nthreads;
        private volatile int readBarrier;
        ReentrantLockLoop(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();
            barrier.await();
            if (print) {
                long time = timer.getTime();
                long tpi = time / ((long)iters * nthreads);
                System.out.print("\t" + LoopHelpers.rightJustify(tpi) + " ns per lock");
                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 + 1;
                int x = sum + 1;
                int n = iters;
                while (n-- > 0) {
                    synchronized(this) {
                        x = LoopHelpers.compute4(x);
                    }
                    sum += x;
                    if ((x += readBarrier) == 0)
                        ++readBarrier;

                }
                barrier.await();
                result += sum;
            }
            catch (Exception ie) {
                return;
            }
        }
    }

}
Revision:	1.3
Committed:	Thu Oct 29 23:09:07 2009 UTC (14 years, 6 months ago) by jsr166
Branch:	MAIN
Changes since 1.2:	+7 -8 lines
Log Message:	whitespace
#	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			* http://creativecommons.org/licenses/publicdomain
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 NoopLockLoops {
12			static final ExecutorService pool = Executors.newCachedThreadPool();
13			static final LoopHelpers.SimpleRandom rng = new LoopHelpers.SimpleRandom();
14			static boolean print = false;
15			static int iters = 20000000;
16
17			public static void main(String[] args) throws Exception {
18			int maxThreads = 100;
19	jsr166	1.3	if (args.length > 0)
20	dl	1.1	maxThreads = Integer.parseInt(args[0]);
21
22			new ReentrantLockLoop(1).test();
23			new ReentrantLockLoop(1).test();
24			print = true;
25
26			int k = 1;
27			for (int i = 1; i <= maxThreads;) {
28			System.out.print("Threads: " + i);
29			new ReentrantLockLoop(i).test();
30			Thread.sleep(100);
31			if (i == k) {
32			k = i << 1;
33			i = i + (i >>> 1);
34	jsr166	1.3	}
35			else
36	dl	1.1	i = k;
37			}
38			pool.shutdown();
39			}
40
41			static final class ReentrantLockLoop implements Runnable {
42			private int v = rng.next();
43			private volatile int result = 17;
44			private final LoopHelpers.BarrierTimer timer = new LoopHelpers.BarrierTimer();
45			private final CyclicBarrier barrier;
46			private final int nthreads;
47			private volatile int readBarrier;
48			ReentrantLockLoop(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			barrier.await();
58			if (print) {
59			long time = timer.getTime();
60			long tpi = time / ((long)iters * nthreads);
61			System.out.print("\t" + LoopHelpers.rightJustify(tpi) + " ns per lock");
62			double secs = (double)(time) / 1000000000.0;
63			System.out.println("\t " + secs + "s run time");
64			}
65
66			int r = result;
67			if (r == 0) // avoid overoptimization
68			System.out.println("useless result: " + r);
69			}
70
71			public final void run() {
72			try {
73	jsr166	1.3	barrier.await();
74	dl	1.1	int sum = v + 1;
75			int x = sum + 1;
76			int n = iters;
77			while (n-- > 0) {
78			synchronized(this) {
79			x = LoopHelpers.compute4(x);
80			}
81			sum += x;
82			if ((x += readBarrier) == 0)
83			++readBarrier;
84
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			}