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// Copyright Yahoo. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
package com.yahoo.concurrent;
import java.util.List;
import java.util.concurrent.atomic.AtomicInteger;
/**
* Benchmark to compare ThreadLocalDirectory with java.util.concurrent's atomic
* variables. Very low precision since it's an adapted unit test.
*
* @author <a href="mailto:steinar@yahoo-inc.com">Steinar Knutsen</a>
*/
public class ThreadLocalDirectoryBenchmark {
private static final int ITERATIONS = 500000;
private final AtomicInteger atomicCounter = new AtomicInteger(0);
private volatile int volatileCounter = 0;
private int naiveCounter = 0;
private static class SumUpdater implements ThreadLocalDirectory.Updater<Integer, Integer> {
@Override
public Integer update(Integer current, Integer x) {
return Integer.valueOf(current.intValue() + x.intValue());
}
@Override
public Integer createGenerationInstance(Integer previous) {
return Integer.valueOf(0);
}
}
private static class Counter implements Runnable {
ThreadLocalDirectory<Integer, Integer> r;
Counter(ThreadLocalDirectory<Integer, Integer> r) {
this.r = r;
}
@Override
public void run() {
LocalInstance<Integer, Integer> s = r.getLocalInstance();
for (int i = 0; i < ITERATIONS; ++i) {
r.update(Integer.valueOf(i), s);
}
}
}
private static class MutableSumUpdater implements ThreadLocalDirectory.Updater<IntWrapper, IntWrapper> {
@Override
public IntWrapper update(IntWrapper current, IntWrapper x) {
current.counter += x.counter;
return current;
}
@Override
public IntWrapper createGenerationInstance(IntWrapper previous) {
return new IntWrapper();
}
}
private static class IntWrapper {
public int counter = 0;
}
private static class WrapperCounter implements Runnable {
ThreadLocalDirectory<IntWrapper, IntWrapper> r;
WrapperCounter(ThreadLocalDirectory<IntWrapper, IntWrapper> r) {
this.r = r;
}
@Override
public void run() {
LocalInstance<IntWrapper, IntWrapper> s = r.getLocalInstance();
IntWrapper w = new IntWrapper();
for (int i = 0; i < ITERATIONS; ++i) {
w.counter = i;
r.update(w, s);
}
}
}
private class AtomicCounter implements Runnable {
@Override
public void run() {
for (int i = 0; i < ITERATIONS; ++i) {
atomicCounter.addAndGet(i);
}
}
}
/**
* This just bangs on a shared volatile to give an idea of the basic cost of
* sharing a single variable with a memory barrier.
*/
private class VolatileSillyness implements Runnable {
@Override
public void run() {
for (int i = 0; i < ITERATIONS; ++i) {
volatileCounter += i;
}
}
}
/**
* This just bangs on a shared to give some sort of lower bound for time
* elapsed.
*/
private class SillySillyness implements Runnable {
@Override
public void run() {
for (int i = 0; i < ITERATIONS; ++i) {
naiveCounter += i;
}
}
}
private void sumFromMultipleThreads() {
SumUpdater updater = new SumUpdater();
ThreadLocalDirectory<Integer, Integer> s = new ThreadLocalDirectory<Integer, Integer>(updater);
Thread[] threads = new Thread[500];
for (int i = 0; i < 500; ++i) {
Counter c = new Counter(s);
threads[i] = new Thread(c);
}
runAll(threads);
List<Integer> measurements = s.fetch();
long sum = 0;
for (Integer i : measurements) {
sum += i.intValue();
}
System.out.println("Sum from all threads: " + sum);
}
private void sumMutableFromMultipleThreads() {
MutableSumUpdater updater = new MutableSumUpdater();
ThreadLocalDirectory<IntWrapper, IntWrapper> s = new ThreadLocalDirectory<IntWrapper, IntWrapper>(updater);
Thread[] threads = new Thread[500];
for (int i = 0; i < 500; ++i) {
WrapperCounter c = new WrapperCounter(s);
threads[i] = new Thread(c);
}
runAll(threads);
List<IntWrapper> measurements = s.fetch();
long sum = 0;
for (IntWrapper i : measurements) {
sum += i.counter;
}
System.out.println("Sum from all threads: " + sum);
}
private void sumAtomicFromMultipleThreads() {
Thread[] threads = new Thread[500];
for (int i = 0; i < 500; ++i) {
AtomicCounter c = new AtomicCounter();
threads[i] = new Thread(c);
}
runAll(threads);
System.out.println("Sum from all threads: " + atomicCounter.get());
}
private void overwriteVolatileFromMultipleThreads() {
Thread[] threads = new Thread[500];
for (int i = 0; i < 500; ++i) {
VolatileSillyness c = new VolatileSillyness();
threads[i] = new Thread(c);
}
runAll(threads);
System.out.println("Checksum from all threads: " + volatileCounter);
}
private void overwriteIntegerFromMultipleThreads() {
Thread[] threads = new Thread[500];
for (int i = 0; i < 500; ++i) {
SillySillyness c = new SillySillyness();
threads[i] = new Thread(c);
}
runAll(threads);
System.out.println("Checksum from all threads: " + volatileCounter);
}
private void runAll(Thread[] threads) {
for (Thread t : threads) {
t.start();
}
for (Thread t : threads) {
try {
t.join();
} catch (InterruptedException e) {
// nop
}
}
}
public static void main(String[] args) {
ThreadLocalDirectoryBenchmark benchmark = new ThreadLocalDirectoryBenchmark();
long end;
System.out.println("ThreadLocalDirectory<Integer, Integer>");
long start = System.currentTimeMillis();
benchmark.sumFromMultipleThreads();
end = System.currentTimeMillis();
System.out.println("Elapsed using threadlocals: " + (end - start) + " ms.");
System.out.println("AtomicInteger");
start = System.currentTimeMillis();
benchmark.sumAtomicFromMultipleThreads();
end = System.currentTimeMillis();
System.out.println("Elapsed using atomic integer: " + (end - start) + " ms.");
System.out.println("volatile int += volatile int");
start = System.currentTimeMillis();
benchmark.overwriteVolatileFromMultipleThreads();
end = System.currentTimeMillis();
System.out.println("Elapsed using single shared volatile: " + (end - start) + " ms.");
System.out.println("int += int");
start = System.currentTimeMillis();
benchmark.overwriteIntegerFromMultipleThreads();
end = System.currentTimeMillis();
System.out.println("Checksum: " + benchmark.naiveCounter);
System.out.println("Elapsed using shared int: " + (end - start) + " ms.");
System.out.println("ThreadLocalDirectory<IntWrapper, IntWrapper>");
start = System.currentTimeMillis();
benchmark.sumMutableFromMultipleThreads();
end = System.currentTimeMillis();
System.out.println("Elapsed using threadlocal with mutable int wrapper: " + (end - start) + " ms.");
}
}
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