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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 static org.junit.Assert.assertEquals;
import static org.junit.Assert.assertNull;
import static org.junit.Assert.assertTrue;
import org.junit.Ignore;
import org.junit.Test;
import java.time.Duration;
import java.util.LinkedList;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.Future;
import java.util.concurrent.LinkedBlockingQueue;
import java.util.concurrent.SynchronousQueue;
import java.util.concurrent.ThreadPoolExecutor;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.atomic.AtomicInteger;
public class ExecutorsTestCase {
static private class Runner implements Runnable {
static private AtomicInteger threadCount = new AtomicInteger(0);
static private class ThreadId extends ThreadLocal<Integer> {
@Override
protected Integer initialValue() {
return threadCount.getAndIncrement();
}
}
static private ThreadId threadId = new ThreadId();
private volatile int runBy = -1;
@Override
public void run() {
runBy = threadId.get();
}
int getRunBy() { return runBy; }
}
private static class Producer implements Runnable {
private volatile int maxThreadId = 0;
private final long timeOutMS;
private final ExecutorService consumer;
Producer(ExecutorService consumer, long timeOutMS) {
this.timeOutMS = timeOutMS;
this.consumer = consumer;
}
@Override
public void run() {
long now = System.currentTimeMillis();
Runner r = new Runner();
try {
while (now + timeOutMS > System.currentTimeMillis()) {
Future<?> f = consumer.submit(r);
f.get();
maxThreadId = Math.max(maxThreadId, r.getRunBy());
Thread.sleep(1);
}
} catch (InterruptedException e) {
assertTrue(false);
} catch (ExecutionException e) {
assertTrue(false);
}
}
}
private void assertThreadId(ExecutorService s, int id) throws InterruptedException, ExecutionException {
Runner r = new Runner();
Future<?> f = s.submit(r);
assertNull(f.get());
assertEquals(id, r.getRunBy());
}
private void assertRoundRobinOrder(ExecutorService s) throws InterruptedException, ExecutionException {
assertThreadId(s, 0);
assertThreadId(s, 1);
assertThreadId(s, 2);
assertThreadId(s, 0);
assertThreadId(s, 1);
assertThreadId(s, 2);
assertThreadId(s, 0);
assertThreadId(s, 1);
}
private int measureMaxNumThreadsUsage(ThreadPoolExecutor s, long durationMS, int maxProducers) throws InterruptedException, ExecutionException {
s.prestartAllCoreThreads();
ExecutorService consumers = Executors.newCachedThreadPool();
LinkedList<Future<Producer>> futures = new LinkedList<>();
for (int i = 0; i < maxProducers; i++) {
Producer p = new Producer(s, durationMS);
futures.add(consumers.submit(p, p));
}
int maxThreadId = 0;
try {
while (! futures.isEmpty()) {
Producer p = futures.remove().get();
maxThreadId = Math.max(maxThreadId, p.maxThreadId);
}
} catch (InterruptedException e) {
assertTrue(false);
} catch (ExecutionException e) {
assertTrue(false);
}
return maxThreadId;
}
private void assertStackOrder(ThreadPoolExecutor s) throws InterruptedException, ExecutionException {
s.prestartAllCoreThreads();
Thread.sleep(10); //Sleep to allow last executing thread to get back on the stack
assertThreadId(s, 0);
Thread.sleep(10);
assertThreadId(s, 0);
Thread.sleep(10);
assertThreadId(s, 0);
Thread.sleep(10);
assertThreadId(s, 0);
Thread.sleep(10);
assertThreadId(s, 0);
Thread.sleep(10);
assertThreadId(s, 0);
Thread.sleep(10);
assertThreadId(s, 0);
}
@Ignore // Ignored as it is not deterministic, and probably hard to make deterministic to.
@Test
public void requireThatExecutionOrderIsPredictable() throws InterruptedException, ExecutionException {
Runner.threadCount.set(0);
assertRoundRobinOrder(new ThreadPoolExecutor(3, 3, 0L, TimeUnit.SECONDS, new LinkedBlockingQueue<Runnable>()));
Runner.threadCount.set(0);
assertRoundRobinOrder(new ThreadPoolExecutor(3, 3, 0L, TimeUnit.SECONDS, new SynchronousQueue<Runnable>(true)));
Runner.threadCount.set(0);
assertStackOrder(new ThreadPoolExecutor(3, 3, 0L, TimeUnit.SECONDS, new SynchronousQueue<Runnable>(false)));
}
@Ignore // Ignored as it might not be deterministic
public void requireThatExecutionOrderIsPredictableUnderLoad() throws InterruptedException, ExecutionException {
Runner.threadCount.set(0);
assertEquals(99, measureMaxNumThreadsUsage(new ThreadPoolExecutor(100, 100, 0L, TimeUnit.SECONDS, new LinkedBlockingQueue<Runnable>()), 3000, 10));
Runner.threadCount.set(0);
assertEquals(99, measureMaxNumThreadsUsage(new ThreadPoolExecutor(100, 100, 0L, TimeUnit.SECONDS, new SynchronousQueue<Runnable>(true)), 3000, 10));
Runner.threadCount.set(0);
//Max 9 concurrent tasks. Might not be deterministic
assertEquals(9, measureMaxNumThreadsUsage(new ThreadPoolExecutor(100, 100, 0L, TimeUnit.SECONDS, new SynchronousQueue<Runnable>(false)), 3000, 10));
Runner.threadCount.set(0);
}
@Test
public void requireHzAndAdjustment() {
assertEquals(1000, SystemTimer.detectHz());
assertEquals(1, SystemTimer.adjustTimeoutByDetectedHz(Duration.ofMillis(1)).toMillis());
assertEquals(20, SystemTimer.adjustTimeoutByDetectedHz(Duration.ofMillis(20)).toMillis());
assertEquals(1, SystemTimer.adjustTimeoutByDetectedHz(Duration.ofMillis(1), 1000).toMillis());
assertEquals(10, SystemTimer.adjustTimeoutByDetectedHz(Duration.ofMillis(1), 100).toMillis());
assertEquals(100, SystemTimer.adjustTimeoutByDetectedHz(Duration.ofMillis(1), 10).toMillis());
assertEquals(20, SystemTimer.adjustTimeoutByDetectedHz(Duration.ofMillis(20), 1000).toMillis());
assertEquals(200, SystemTimer.adjustTimeoutByDetectedHz(Duration.ofMillis(20), 100).toMillis());
assertEquals(2000, SystemTimer.adjustTimeoutByDetectedHz(Duration.ofMillis(20), 10).toMillis());
}
}
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