test/loops/SimpleReentrantConditionWaitLoops.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.*;

/**
 * A variant of SimpleReentrantLockLoops that also has a very short timed wait.
 * Demonstrates 2% performance improvement on x86 with weakened atomics in AQS.
 */
public final class SimpleReentrantConditionWaitLoops {
    static final ExecutorService pool = Executors.newCachedThreadPool();
    static final LoopHelpers.SimpleRandom rng = new LoopHelpers.SimpleRandom();
    static final int ITERS = Integer.getInteger("iters", 2000000);
    static final int MAX_THREADS = Integer.getInteger("maxThreads", 1);
    static boolean print = false;

    public static void main(String[] args) throws Exception {

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

        for (int k = 1, i = 1; i <= MAX_THREADS;) {
            System.out.print("Threads: " + i);
            new ReentrantConditionWaitLoop(i).test();
            Thread.sleep(10);
            if (i == k) {
                k = i << 1;
                i = i + (i >>> 1);
            }
            else
                i = k;
        }
        pool.shutdown();
        if (!pool.awaitTermination(10, TimeUnit.SECONDS))
            throw new Error("pool failed to terminate!");
    }

    static final class ReentrantConditionWaitLoop implements Runnable {
        private int v = rng.next();
        private volatile int result = 17;
        private final ReentrantLock lock = new ReentrantLock();
        private final LoopHelpers.BarrierTimer timer = new LoopHelpers.BarrierTimer();
        private final CyclicBarrier barrier;
        private final int nthreads;
        private volatile int readBarrier;
        ReentrantConditionWaitLoop(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 ReentrantLock lock = this.lock;
            final Condition condition = lock.newCondition();
            try {
                barrier.await();
                int sum = v + 1;
                int x = 0;
                int n = ITERS;
                while (n-- > 0) {
                    lock.lock();
                    condition.await(10, TimeUnit.NANOSECONDS);
                    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:	1.3
Committed:	Wed Dec 31 17:00:58 2014 UTC (9 years, 4 months ago) by jsr166
Branch:	MAIN
Changes since 1.2:	+1 -1 lines
Log Message:	lexicographic import order
#	User	Rev	Content
1	jsr166	1.1	/*
2			* Written by Doug Lea with assistance from members of JCP JSR-166
3			* Expert Group and released to the public domain, as explained at
4			* http://creativecommons.org/publicdomain/zero/1.0/
5			*/
6
7	jsr166	1.3	import java.util.*;
8	jsr166	1.1	import java.util.concurrent.*;
9			import java.util.concurrent.locks.*;
10
11			/**
12			* A variant of SimpleReentrantLockLoops that also has a very short timed wait.
13			* Demonstrates 2% performance improvement on x86 with weakened atomics in AQS.
14			*/
15			public final class SimpleReentrantConditionWaitLoops {
16			static final ExecutorService pool = Executors.newCachedThreadPool();
17			static final LoopHelpers.SimpleRandom rng = new LoopHelpers.SimpleRandom();
18	jsr166	1.2	static final int ITERS = Integer.getInteger("iters", 2000000);
19	jsr166	1.1	static final int MAX_THREADS = Integer.getInteger("maxThreads", 1);
20			static boolean print = false;
21
22			public static void main(String[] args) throws Exception {
23
24			new ReentrantConditionWaitLoop(1).test();
25			new ReentrantConditionWaitLoop(1).test();
26			print = true;
27
28			for (int k = 1, i = 1; i <= MAX_THREADS;) {
29			System.out.print("Threads: " + i);
30			new ReentrantConditionWaitLoop(i).test();
31			Thread.sleep(10);
32			if (i == k) {
33			k = i << 1;
34			i = i + (i >>> 1);
35			}
36			else
37			i = k;
38			}
39			pool.shutdown();
40			if (!pool.awaitTermination(10, TimeUnit.SECONDS))
41			throw new Error("pool failed to terminate!");
42			}
43
44			static final class ReentrantConditionWaitLoop implements Runnable {
45			private int v = rng.next();
46			private volatile int result = 17;
47			private final ReentrantLock lock = new ReentrantLock();
48			private final LoopHelpers.BarrierTimer timer = new LoopHelpers.BarrierTimer();
49			private final CyclicBarrier barrier;
50			private final int nthreads;
51			private volatile int readBarrier;
52			ReentrantConditionWaitLoop(int nthreads) {
53			this.nthreads = nthreads;
54			barrier = new CyclicBarrier(nthreads+1, timer);
55			}
56
57			final void test() throws Exception {
58			for (int i = 0; i < nthreads; ++i)
59			pool.execute(this);
60			barrier.await();
61			barrier.await();
62			if (print) {
63			long time = timer.getTime();
64			long tpi = time / ((long) ITERS * nthreads);
65			System.out.print("\t" + LoopHelpers.rightJustify(tpi) + " ns per lock");
66			double secs = (double) time / 1000000000.0;
67			System.out.println("\t " + secs + "s run time");
68			}
69
70			int r = result;
71			if (r == 0) // avoid overoptimization
72			System.out.println("useless result: " + r);
73			}
74
75			public final void run() {
76			final ReentrantLock lock = this.lock;
77			final Condition condition = lock.newCondition();
78			try {
79			barrier.await();
80			int sum = v + 1;
81			int x = 0;
82			int n = ITERS;
83			while (n-- > 0) {
84			lock.lock();
85			condition.await(10, TimeUnit.NANOSECONDS);
86			int k = (sum & 3);
87			if (k > 0) {
88			x = v;
89			while (k-- > 0)
90			x = LoopHelpers.compute6(x);
91			v = x;
92			}
93			else x = sum + 1;
94			lock.unlock();
95			if ((x += readBarrier) == 0)
96			++readBarrier;
97			for (int l = x & 7; l > 0; --l)
98			sum += LoopHelpers.compute6(sum);
99			}
100			barrier.await();
101			result += sum;
102			}
103			catch (Exception ie) {
104			return;
105			}
106			}
107			}
108
109			}