test/loops/ContextSwitchTest.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/licenses/publicdomain
 */

import java.util.concurrent.*;
import java.util.concurrent.locks.*;
import java.util.concurrent.atomic.*;
import java.util.*;

public final class ContextSwitchTest {
    final static int iters = 1000000;
    static AtomicReference turn = new AtomicReference();
    public static void main(String[] args) throws Exception {
        MyThread a = new MyThread();
        MyThread b = new MyThread();
        a.other = b;
        b.other = a;
        turn.set(a);
        long startTime = System.nanoTime();
        a.start();
        b.start();
        a.join();
        b.join();
        long endTime = System.nanoTime();
        int np = a.nparks + b.nparks;
        System.out.println((endTime - startTime) / np);
    }

    private static int nextRandom(int x) { 
        int t = (x % 127773) * 16807 - (x / 127773) * 2836;
        return (t > 0)? t : t + 0x7fffffff;
    }

    static final class MyThread extends Thread {
        volatile Thread other;
        volatile int nparks;
        volatile int result;

        public void run() {
            int x = 17;
            int p = 0;
            for (int i = 0; i < iters; ++i) {
                while (!turn.compareAndSet(other, this)) {
                    LockSupport.park();
                    ++p;
                }
                x = nextRandom(x);
                LockSupport.unpark(other);
            }
            LockSupport.unpark(other);
            nparks = p;
            result = x;
            System.out.println("parks: " + p);
            
        }
    }
}


Revision:	1.2
Committed:	Mon May 9 19:33:30 2005 UTC (19 years ago) by dl
Branch:	MAIN
Changes since 1.1:	+6 -0 lines
Log Message:	Add headers
#	User	Rev	Content
1	dl	1.2	/*
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/licenses/publicdomain
5			*/
6
7	dl	1.1	import java.util.concurrent.*;
8			import java.util.concurrent.locks.*;
9			import java.util.concurrent.atomic.*;
10			import java.util.*;
11
12			public final class ContextSwitchTest {
13			final static int iters = 1000000;
14			static AtomicReference turn = new AtomicReference();
15			public static void main(String[] args) throws Exception {
16			MyThread a = new MyThread();
17			MyThread b = new MyThread();
18			a.other = b;
19			b.other = a;
20			turn.set(a);
21			long startTime = System.nanoTime();
22			a.start();
23			b.start();
24			a.join();
25			b.join();
26			long endTime = System.nanoTime();
27			int np = a.nparks + b.nparks;
28			System.out.println((endTime - startTime) / np);
29			}
30
31			private static int nextRandom(int x) {
32			int t = (x % 127773) * 16807 - (x / 127773) * 2836;
33			return (t > 0)? t : t + 0x7fffffff;
34			}
35
36			static final class MyThread extends Thread {
37			volatile Thread other;
38			volatile int nparks;
39			volatile int result;
40
41			public void run() {
42			int x = 17;
43			int p = 0;
44			for (int i = 0; i < iters; ++i) {
45			while (!turn.compareAndSet(other, this)) {
46			LockSupport.park();
47			++p;
48			}
49			x = nextRandom(x);
50			LockSupport.unpark(other);
51			}
52			LockSupport.unpark(other);
53			nparks = p;
54			result = x;
55			System.out.println("parks: " + p);
56
57			}
58			}
59			}
60
61