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.concurrent.CyclicBarrier;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.locks.Condition;
import java.util.concurrent.locks.ReentrantLock;

/**
 * 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:	1.4
Committed:	Sat Dec 31 19:32:00 2016 UTC (7 years, 4 months ago) by jsr166
Branch:	MAIN
CVS Tags:	HEAD
Changes since 1.3:	+6 -3 lines
Log Message:	organize imports
#	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	1.4	import java.util.concurrent.CyclicBarrier;
8			import java.util.concurrent.ExecutorService;
9			import java.util.concurrent.Executors;
10			import java.util.concurrent.TimeUnit;
11			import java.util.concurrent.locks.Condition;
12			import java.util.concurrent.locks.ReentrantLock;
13	jsr166	1.1
14			/**
15			* A variant of SimpleReentrantLockLoops that also has a very short timed wait.
16			* Demonstrates 2% performance improvement on x86 with weakened atomics in AQS.
17			*/
18			public final class SimpleReentrantConditionWaitLoops {
19			static final ExecutorService pool = Executors.newCachedThreadPool();
20			static final LoopHelpers.SimpleRandom rng = new LoopHelpers.SimpleRandom();
21	jsr166	1.2	static final int ITERS = Integer.getInteger("iters", 2000000);
22	jsr166	1.1	static final int MAX_THREADS = Integer.getInteger("maxThreads", 1);
23			static boolean print = false;
24
25			public static void main(String[] args) throws Exception {
26
27			new ReentrantConditionWaitLoop(1).test();
28			new ReentrantConditionWaitLoop(1).test();
29			print = true;
30
31			for (int k = 1, i = 1; i <= MAX_THREADS;) {
32			System.out.print("Threads: " + i);
33			new ReentrantConditionWaitLoop(i).test();
34			Thread.sleep(10);
35			if (i == k) {
36			k = i << 1;
37			i = i + (i >>> 1);
38			}
39			else
40			i = k;
41			}
42			pool.shutdown();
43			if (!pool.awaitTermination(10, TimeUnit.SECONDS))
44			throw new Error("pool failed to terminate!");
45			}
46
47			static final class ReentrantConditionWaitLoop implements Runnable {
48			private int v = rng.next();
49			private volatile int result = 17;
50			private final ReentrantLock lock = new ReentrantLock();
51			private final LoopHelpers.BarrierTimer timer = new LoopHelpers.BarrierTimer();
52			private final CyclicBarrier barrier;
53			private final int nthreads;
54			private volatile int readBarrier;
55			ReentrantConditionWaitLoop(int nthreads) {
56			this.nthreads = nthreads;
57			barrier = new CyclicBarrier(nthreads+1, timer);
58			}
59
60			final void test() throws Exception {
61			for (int i = 0; i < nthreads; ++i)
62			pool.execute(this);
63			barrier.await();
64			barrier.await();
65			if (print) {
66			long time = timer.getTime();
67			long tpi = time / ((long) ITERS * nthreads);
68			System.out.print("\t" + LoopHelpers.rightJustify(tpi) + " ns per lock");
69			double secs = (double) time / 1000000000.0;
70			System.out.println("\t " + secs + "s run time");
71			}
72
73			int r = result;
74			if (r == 0) // avoid overoptimization
75			System.out.println("useless result: " + r);
76			}
77
78			public final void run() {
79			final ReentrantLock lock = this.lock;
80			final Condition condition = lock.newCondition();
81			try {
82			barrier.await();
83			int sum = v + 1;
84			int x = 0;
85			int n = ITERS;
86			while (n-- > 0) {
87			lock.lock();
88			condition.await(10, TimeUnit.NANOSECONDS);
89			int k = (sum & 3);
90			if (k > 0) {
91			x = v;
92			while (k-- > 0)
93			x = LoopHelpers.compute6(x);
94			v = x;
95			}
96			else x = sum + 1;
97			lock.unlock();
98			if ((x += readBarrier) == 0)
99			++readBarrier;
100			for (int l = x & 7; l > 0; --l)
101			sum += LoopHelpers.compute6(sum);
102			}
103			barrier.await();
104			result += sum;
105			}
106			catch (Exception ie) {
107			return;
108			}
109			}
110			}
111
112			}