| /** |
| * 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 com.google.common.util.concurrent.MoreExecutors; |
| |
| 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. |
| * <p> |
| * This is inspired by <a href="https://github.com/apache/incubator-s4/blob/master/subprojects/s4-comm/src/main/java/org/apache/s4/comm/staging/BlockingThreadPoolExecutorService.java"> |
| * this s4 threadpool</a> |
| */ |
| @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(MoreExecutors.listeningDecorator(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<Runnable> 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()); |
| sb.append(", activeCount=").append(getActiveCount()); |
| sb.append('}'); |
| return sb.toString(); |
| } |
| } |