48 lines
1.2 KiB
Java
48 lines
1.2 KiB
Java
//: concurrency/SimpleMicroBenchmark.java
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// The dangers of microbenchmarking.
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import java.util.concurrent.locks.*;
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abstract class Incrementable {
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protected long counter = 0;
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public abstract void increment();
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}
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class SynchronizingTest extends Incrementable {
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@Override
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public synchronized void increment() { ++counter; }
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}
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class LockingTest extends Incrementable {
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private Lock lock = new ReentrantLock();
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@Override
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public void increment() {
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lock.lock();
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try {
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++counter;
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} finally {
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lock.unlock();
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}
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}
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}
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public class SimpleMicroBenchmark {
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static long test(Incrementable incr) {
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long start = System.nanoTime();
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for(long i = 0; i < 10000000L; i++)
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incr.increment();
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return System.nanoTime() - start;
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}
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public static void main(String[] args) {
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long synchTime = test(new SynchronizingTest());
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long lockTime = test(new LockingTest());
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System.out.printf("synchronized: %1$10d\n", synchTime);
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System.out.printf("Lock: %1$10d\n", lockTime);
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System.out.printf("Lock/synchronized = %1$.3f",
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(double)lockTime/(double)synchTime);
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}
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} /* Output: (75% match)
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synchronized: 244919117
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Lock: 939098964
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Lock/synchronized = 3.834
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*///:~
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