test/loops/SimpleLockLoops.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.CyclicBarrier;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;

public final class SimpleLockLoops {
    static final ExecutorService pool = Executors.newCachedThreadPool();
    static final LoopHelpers.SimpleRandom rng = new LoopHelpers.SimpleRandom();
    static boolean print = false;
    static int iters = 2000000;

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

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

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

    static final class LockLoop implements Runnable {
        private int v = rng.next();
        private volatile int result = 17;
        private final Object lock = new Object();
        private final LoopHelpers.BarrierTimer timer = new LoopHelpers.BarrierTimer();
        private final CyclicBarrier barrier;
        private final int nthreads;
        private volatile int readBarrier;
        LockLoop(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() {
            final Object lock = this.lock;
            try {
                barrier.await();
                int sum = v + 1;
                int x = 0;
                int n = iters;
                while (n-- > 0) {
                    synchronized (lock) {
                        int k = (sum & 3);
                        if (k > 0) {
                            x = v;
                            while (k-- > 0)
                                x = LoopHelpers.compute6(x);
                            v = x;
                        }
                        else x = sum + 1;
                    }
                    if ((x += readBarrier) == 0)
                        ++readBarrier;
                    for (int l = x & 7; l > 0; --l)
                        sum += LoopHelpers.compute6(sum);
                }
                barrier.await();
                result += sum;
            }
            catch (Exception ie) {
                return;
            }
        }
    }

}
Revision:	1.11
Committed:	Sat Dec 31 02:19:51 2016 UTC (7 years, 4 months ago) by jsr166
Branch:	MAIN
CVS Tags:	HEAD
Changes since 1.10:	+3 -3 lines
Log Message:	organize imports
#	User	Rev	Content
1	dl	1.1	/*
2			* Written by Doug Lea with assistance from members of JCP JSR-166
3	dl	1.3	* Expert Group and released to the public domain, as explained at
4	jsr166	1.8	* http://creativecommons.org/publicdomain/zero/1.0/
5	dl	1.1	*/
6
7	jsr166	1.11	import java.util.concurrent.CyclicBarrier;
8			import java.util.concurrent.ExecutorService;
9			import java.util.concurrent.Executors;
10	dl	1.1
11			public final class SimpleLockLoops {
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 = 2000000;
16
17			public static void main(String[] args) throws Exception {
18			int maxThreads = 100;
19	jsr166	1.5	if (args.length > 0)
20	dl	1.1	maxThreads = Integer.parseInt(args[0]);
21
22	dl	1.4	new LockLoop(1).test();
23			new LockLoop(1).test();
24	dl	1.1	print = true;
25
26	jsr166	1.9	for (int k = 1, i = 1; i <= maxThreads;) {
27	dl	1.1	System.out.print("Threads: " + i);
28	dl	1.4	new LockLoop(i).test();
29	dl	1.1	Thread.sleep(100);
30			if (i == k) {
31			k = i << 1;
32			i = i + (i >>> 1);
33	jsr166	1.5	}
34			else
35	dl	1.1	i = k;
36			}
37			pool.shutdown();
38			}
39
40	dl	1.4	static final class LockLoop implements Runnable {
41	dl	1.1	private int v = rng.next();
42			private volatile int result = 17;
43	dl	1.4	private final Object lock = new Object();
44	dl	1.1	private final LoopHelpers.BarrierTimer timer = new LoopHelpers.BarrierTimer();
45			private final CyclicBarrier barrier;
46			private final int nthreads;
47			private volatile int readBarrier;
48	dl	1.4	LockLoop(int nthreads) {
49	dl	1.1	this.nthreads = nthreads;
50			barrier = new CyclicBarrier(nthreads+1, timer);
51			}
52
53			final void test() throws Exception {
54	jsr166	1.5	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	jsr166	1.6	long tpi = time / ((long) iters * nthreads);
61	dl	1.1	System.out.print("\t" + LoopHelpers.rightJustify(tpi) + " ns per lock");
62	jsr166	1.6	double secs = (double) time / 1000000000.0;
63	dl	1.1	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	dl	1.4	final Object lock = this.lock;
73	dl	1.1	try {
74	jsr166	1.5	barrier.await();
75	dl	1.1	int sum = v + 1;
76			int x = 0;
77			int n = iters;
78			while (n-- > 0) {
79	jsr166	1.7	synchronized (lock) {
80	dl	1.1	int k = (sum & 3);
81			if (k > 0) {
82			x = v;
83			while (k-- > 0)
84	dl	1.2	x = LoopHelpers.compute6(x);
85	dl	1.1	v = x;
86			}
87			else x = sum + 1;
88			}
89			if ((x += readBarrier) == 0)
90			++readBarrier;
91			for (int l = x & 7; l > 0; --l)
92	dl	1.2	sum += LoopHelpers.compute6(sum);
93	jsr166	1.5	}
94	dl	1.1	barrier.await();
95			result += sum;
96			}
97	jsr166	1.5	catch (Exception ie) {
98			return;
99	dl	1.1	}
100			}
101			}
102
103			}