// Copyright 2017 JanusGraph Authors
//
// Licensed 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.janusgraph.graphdb.util;
import java.util.concurrent.LinkedBlockingQueue;
import java.util.concurrent.ThreadPoolExecutor;
import java.util.concurrent.TimeUnit;
/**
* Utility class for implementing a thread pool that closes gracefully and provides back-pressure when submitting jobs.
*
* @author Matthias Broecheler (me@matthiasb.com)
*/
public class WorkerPool implements AutoCloseable {
private final ThreadPoolExecutor processor;
private final long shutdownWaitMS = 10000;
public WorkerPool(int numThreads) {
processor = new ThreadPoolExecutor(numThreads, numThreads, 0L, TimeUnit.MILLISECONDS, new LinkedBlockingQueue<Runnable>(128));
processor.setRejectedExecutionHandler(new ThreadPoolExecutor.CallerRunsPolicy());
}
public void submit(Runnable runnable) {
processor.submit(runnable);
}
@Override
public void close() throws Exception {
processor.shutdown();
processor.awaitTermination(shutdownWaitMS,TimeUnit.MILLISECONDS);
if (!processor.isTerminated()) {
//log.error("Processor did not terminate in time");
processor.shutdownNow();
}
}
}