test/loops/SimpleLoops.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.*;
import java.util.concurrent.*;
import java.util.concurrent.locks.*;

public final class SimpleLoops {
    static final ExecutorService pool = Executors.newCachedThreadPool();
    static final LoopHelpers.SimpleRandom rng = new LoopHelpers.SimpleRandom();
    static boolean print = false;
    static int iters = 10000000;

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

        print = true;

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

    static final class Loop 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;
        Loop(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 = 0;
                int n = iters;
                while (n-- > 0) {
                    int k = (sum & 3);
                    if (k > 0) {
                        x = v;
                        while (k-- > 0)
                            x = LoopHelpers.compute1(x);
                        v = x;
                    }
                    else x = sum + 1;
                    if ((x += readBarrier) == 0)
                        ++readBarrier;
                    for (int l = x & 7; l > 0; --l)
                        sum += LoopHelpers.compute1(sum);
                }
                barrier.await();
                result += sum;
            }
            catch (Exception ie) {
                return;
            }
        }
    }

}
Revision:	1.7
Committed:	Wed Dec 31 17:00:58 2014 UTC (9 years, 4 months ago) by jsr166
Branch:	MAIN
Changes since 1.6:	+1 -1 lines
Log Message:	lexicographic import order
#	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	jsr166	1.7	import java.util.*;
7	dl	1.1	import java.util.concurrent.*;
8			import java.util.concurrent.locks.*;
9
10			public final class SimpleLoops {
11			static final ExecutorService pool = Executors.newCachedThreadPool();
12			static final LoopHelpers.SimpleRandom rng = new LoopHelpers.SimpleRandom();
13			static boolean print = false;
14			static int iters = 10000000;
15
16			public static void main(String[] args) throws Exception {
17			int maxThreads = 100;
18	jsr166	1.3	if (args.length > 0)
19	dl	1.1	maxThreads = Integer.parseInt(args[0]);
20
21			print = true;
22
23	jsr166	1.6	for (int k = 1, i = 1; i <= maxThreads;) {
24	dl	1.1	System.out.print("Threads: " + 1);
25			new Loop(1).test();
26			Thread.sleep(100);
27			if (i == k) {
28			k = i << 1;
29			i = i + (i >>> 1);
30	jsr166	1.3	}
31			else
32	dl	1.1	i = k;
33			}
34			pool.shutdown();
35			}
36
37			static final class Loop implements Runnable {
38			private int v = rng.next();
39			private volatile int result = 17;
40			private final LoopHelpers.BarrierTimer timer = new LoopHelpers.BarrierTimer();
41			private final CyclicBarrier barrier;
42			private final int nthreads;
43			private volatile int readBarrier;
44			Loop(int nthreads) {
45			this.nthreads = nthreads;
46			barrier = new CyclicBarrier(nthreads+1, timer);
47			}
48
49			final void test() throws Exception {
50	jsr166	1.3	for (int i = 0; i < nthreads; ++i)
51	dl	1.1	pool.execute(this);
52			barrier.await();
53			barrier.await();
54			if (print) {
55			long time = timer.getTime();
56	jsr166	1.4	long tpi = time / ((long) iters * nthreads);
57	dl	1.1	System.out.print("\t" + LoopHelpers.rightJustify(tpi) + " ns per lock");
58	jsr166	1.4	double secs = (double) time / 1000000000.0;
59	dl	1.1	System.out.println("\t " + secs + "s run time");
60			}
61
62			int r = result;
63			if (r == 0) // avoid overoptimization
64			System.out.println("useless result: " + r);
65			}
66
67			public final void run() {
68			try {
69	jsr166	1.3	barrier.await();
70	dl	1.1	int sum = v + 1;
71			int x = 0;
72			int n = iters;
73			while (n-- > 0) {
74			int k = (sum & 3);
75			if (k > 0) {
76			x = v;
77			while (k-- > 0)
78			x = LoopHelpers.compute1(x);
79			v = x;
80			}
81			else x = sum + 1;
82			if ((x += readBarrier) == 0)
83			++readBarrier;
84			for (int l = x & 7; l > 0; --l)
85			sum += LoopHelpers.compute1(sum);
86	jsr166	1.3	}
87	dl	1.1	barrier.await();
88			result += sum;
89			}
90	jsr166	1.3	catch (Exception ie) {
91			return;
92	dl	1.1	}
93			}
94			}
95
96			}