org.apache.hadoop.util.BlockingThreadPoolExecutorService Maven / Gradle / Ivy
/**
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.hadoop.util;
import java.util.concurrent.BlockingQueue;
import java.util.concurrent.LinkedBlockingQueue;
import java.util.concurrent.RejectedExecutionHandler;
import java.util.concurrent.ThreadFactory;
import java.util.concurrent.ThreadPoolExecutor;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.atomic.AtomicInteger;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.apache.hadoop.classification.InterfaceAudience;
/**
* This ExecutorService blocks the submission of new tasks when its queue is
* already full by using a semaphore. Task submissions require permits, task
* completions release permits.
*
* This is inspired by
* this s4 threadpool
*/
@InterfaceAudience.Private
public final class BlockingThreadPoolExecutorService
extends SemaphoredDelegatingExecutor {
private static final Logger LOG = LoggerFactory
.getLogger(BlockingThreadPoolExecutorService.class);
private static final AtomicInteger POOLNUMBER = new AtomicInteger(1);
private final ThreadPoolExecutor eventProcessingExecutor;
/**
* Returns a {@link java.util.concurrent.ThreadFactory} that names each
* created thread uniquely,
* with a common prefix.
*
* @param prefix The prefix of every created Thread's name
* @return a {@link java.util.concurrent.ThreadFactory} that names threads
*/
static ThreadFactory getNamedThreadFactory(final String prefix) {
SecurityManager s = System.getSecurityManager();
final ThreadGroup threadGroup = (s != null) ? s.getThreadGroup() :
Thread.currentThread().getThreadGroup();
return new ThreadFactory() {
private final AtomicInteger threadNumber = new AtomicInteger(1);
private final int poolNum = POOLNUMBER.getAndIncrement();
private final ThreadGroup group = threadGroup;
@Override
public Thread newThread(Runnable r) {
final String name =
prefix + "-pool" + poolNum + "-t" + threadNumber.getAndIncrement();
return new Thread(group, r, name);
}
};
}
/**
* Get a named {@link ThreadFactory} that just builds daemon threads.
*
* @param prefix name prefix for all threads created from the factory
* @return a thread factory that creates named, daemon threads with
* the supplied exception handler and normal priority
*/
public static ThreadFactory newDaemonThreadFactory(final String prefix) {
final ThreadFactory namedFactory = getNamedThreadFactory(prefix);
return new ThreadFactory() {
@Override
public Thread newThread(Runnable r) {
Thread t = namedFactory.newThread(r);
if (!t.isDaemon()) {
t.setDaemon(true);
}
if (t.getPriority() != Thread.NORM_PRIORITY) {
t.setPriority(Thread.NORM_PRIORITY);
}
return t;
}
};
}
private BlockingThreadPoolExecutorService(int permitCount,
ThreadPoolExecutor eventProcessingExecutor) {
super(eventProcessingExecutor, permitCount, false);
this.eventProcessingExecutor = eventProcessingExecutor;
}
/**
* A thread pool that that blocks clients submitting additional tasks if
* there are already {@code activeTasks} running threads and {@code
* waitingTasks} tasks waiting in its queue.
*
* @param activeTasks maximum number of active tasks
* @param waitingTasks maximum number of waiting tasks
* @param keepAliveTime time until threads are cleaned up in {@code unit}
* @param unit time unit
* @param prefixName prefix of name for threads
*/
public static BlockingThreadPoolExecutorService newInstance(
int activeTasks,
int waitingTasks,
long keepAliveTime, TimeUnit unit,
String prefixName) {
/* Although we generally only expect up to waitingTasks tasks in the
queue, we need to be able to buffer all tasks in case dequeueing is
slower than enqueueing. */
final BlockingQueue workQueue =
new LinkedBlockingQueue<>(waitingTasks + activeTasks);
ThreadPoolExecutor eventProcessingExecutor =
new ThreadPoolExecutor(activeTasks, activeTasks, keepAliveTime, unit,
workQueue, newDaemonThreadFactory(prefixName),
new RejectedExecutionHandler() {
@Override
public void rejectedExecution(Runnable r,
ThreadPoolExecutor executor) {
// This is not expected to happen.
LOG.error("Could not submit task to executor {}",
executor.toString());
}
});
eventProcessingExecutor.allowCoreThreadTimeOut(true);
return new BlockingThreadPoolExecutorService(waitingTasks + activeTasks,
eventProcessingExecutor);
}
/**
* Get the actual number of active threads.
* @return the active thread count
*/
int getActiveCount() {
return eventProcessingExecutor.getActiveCount();
}
@Override
public String toString() {
final StringBuilder sb = new StringBuilder(
"BlockingThreadPoolExecutorService{");
sb.append(super.toString())
.append(", activeCount=").append(getActiveCount())
.append('}');
return sb.toString();
}
}