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/* |
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* Written by Doug Lea with assistance from members of JCP JSR-166 |
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* Expert Group and released to the public domain, as explained at |
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* http://creativecommons.org/licenses/publicdomain |
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*/ |
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|
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import java.util.concurrent.*; |
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import java.util.concurrent.locks.*; |
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import java.util.concurrent.atomic.*; |
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import java.util.*; |
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|
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public final class ContextSwitchTest { |
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final static int iters = 1000000; |
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static AtomicReference turn = new AtomicReference(); |
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public static void main(String[] args) throws Exception { |
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MyThread a = new MyThread(); |
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MyThread b = new MyThread(); |
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a.other = b; |
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b.other = a; |
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turn.set(a); |
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long startTime = System.nanoTime(); |
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a.start(); |
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b.start(); |
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a.join(); |
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b.join(); |
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long endTime = System.nanoTime(); |
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int np = a.nparks + b.nparks; |
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System.out.println((endTime - startTime) / np); |
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} |
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|
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private static int nextRandom(int x) { |
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int t = (x % 127773) * 16807 - (x / 127773) * 2836; |
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return (t > 0)? t : t + 0x7fffffff; |
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} |
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|
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static final class MyThread extends Thread { |
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volatile Thread other; |
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volatile int nparks; |
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volatile int result; |
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|
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public void run() { |
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int x = 17; |
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int p = 0; |
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for (int i = 0; i < iters; ++i) { |
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while (!turn.compareAndSet(other, this)) { |
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LockSupport.park(); |
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++p; |
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} |
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x = nextRandom(x); |
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LockSupport.unpark(other); |
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} |
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LockSupport.unpark(other); |
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nparks = p; |
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result = x; |
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System.out.println("parks: " + p); |
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|
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} |
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} |
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} |
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