test/loops/SimpleWriteLockLoops.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 SimpleWriteLockLoops {
    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;

        int reps = 2;
        for (int i = 1; i <= maxThreads; i += (i+1) >>> 1) {
            int n = reps;
            if (reps > 1) --reps;
            while (n-- > 0) {
                System.out.print("Threads: " + i);
                new WriteLockLoop(i).test();
                Thread.sleep(100);
            }
        }
        pool.shutdown();
    }

    static final class WriteLockLoop implements Runnable {
        private int v = rng.next();
        private volatile int result = 17;
        private volatile int readBarrier;
        private final ReentrantReadWriteLock lock = new ReentrantReadWriteLock();
        private final LoopHelpers.BarrierTimer timer = new LoopHelpers.BarrierTimer();
        private final CyclicBarrier barrier;
        private final int nthreads;
        WriteLockLoop(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 Lock lock = this.lock.writeLock();
            try {
                barrier.await();
                int sum = v + 1;
                int x = 0;
                int n = iters;
                while (n-- > 0) {
                    lock.lock();
                    int k = (sum & 3);
                    if (k > 0) {
                        x = v;
                        while (k-- > 0)
                            x = LoopHelpers.compute6(x);
                        v = x;
                    }
                    else x = sum + 1;
                    lock.unlock();
                    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:	1.7
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	1.3	* Expert Group and released to the public domain, as explained at
4	jsr166	1.6	* http://creativecommons.org/publicdomain/zero/1.0/
5	dl	1.1	*/
6
7	jsr166	1.7	import java.util.*;
8	dl	1.1	import java.util.concurrent.*;
9			import java.util.concurrent.locks.*;
10
11			public final class SimpleWriteLockLoops {
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 = 10000000;
16
17			public static void main(String[] args) throws Exception {
18			int maxThreads = 100;
19	jsr166	1.4	if (args.length > 0)
20	dl	1.1	maxThreads = Integer.parseInt(args[0]);
21
22			print = true;
23
24			int reps = 2;
25			for (int i = 1; i <= maxThreads; i += (i+1) >>> 1) {
26			int n = reps;
27			if (reps > 1) --reps;
28			while (n-- > 0) {
29			System.out.print("Threads: " + i);
30			new WriteLockLoop(i).test();
31			Thread.sleep(100);
32			}
33			}
34			pool.shutdown();
35			}
36
37			static final class WriteLockLoop implements Runnable {
38			private int v = rng.next();
39			private volatile int result = 17;
40			private volatile int readBarrier;
41			private final ReentrantReadWriteLock lock = new ReentrantReadWriteLock();
42			private final LoopHelpers.BarrierTimer timer = new LoopHelpers.BarrierTimer();
43			private final CyclicBarrier barrier;
44			private final int nthreads;
45			WriteLockLoop(int nthreads) {
46			this.nthreads = nthreads;
47			barrier = new CyclicBarrier(nthreads+1, timer);
48			}
49
50			final void test() throws Exception {
51	jsr166	1.4	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	1.5	long tpi = time / ((long) iters * nthreads);
58	dl	1.1	System.out.print("\t" + LoopHelpers.rightJustify(tpi) + " ns per lock");
59	jsr166	1.5	double secs = (double) time / 1000000000.0;
60	dl	1.1	System.out.println("\t " + secs + "s run time");
61			}
62
63			int r = result;
64			if (r == 0) // avoid overoptimization
65			System.out.println("useless result: " + r);
66			}
67
68			public final void run() {
69			final Lock lock = this.lock.writeLock();
70			try {
71	jsr166	1.4	barrier.await();
72	dl	1.1	int sum = v + 1;
73			int x = 0;
74			int n = iters;
75			while (n-- > 0) {
76			lock.lock();
77			int k = (sum & 3);
78			if (k > 0) {
79			x = v;
80			while (k-- > 0)
81	dl	1.2	x = LoopHelpers.compute6(x);
82	dl	1.1	v = x;
83			}
84			else x = sum + 1;
85			lock.unlock();
86			if ((x += readBarrier) == 0)
87			++readBarrier;
88			for (int l = x & 7; l > 0; --l)
89	dl	1.2	sum += LoopHelpers.compute6(sum);
90	jsr166	1.4	}
91	dl	1.1	barrier.await();
92			result += sum;
93			}
94	jsr166	1.4	catch (Exception ie) {
95			return;
96	dl	1.1	}
97			}
98			}
99
100			}