org.polymap.core.runtime.UnboundPoolExecutor.java Source code

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Here is the source code for org.polymap.core.runtime.UnboundPoolExecutor.java

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/* 
 * polymap.org
 * Copyright 2013, Falko Brutigam. All rights reserved.
 *
 * This is free software; you can redistribute it and/or modify it
 * under the terms of the GNU Lesser General Public License as
 * published by the Free Software Foundation; either version 2.1 of
 * the License, or (at your option) any later version.
 *
 * This software is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
 * Lesser General Public License for more details.
 */
package org.polymap.core.runtime;

import java.util.Random;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.RejectedExecutionHandler;
import java.util.concurrent.SynchronousQueue;
import java.util.concurrent.ThreadFactory;
import java.util.concurrent.ThreadPoolExecutor;
import java.util.concurrent.TimeUnit;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

/**
 * A thread pool executor with (nearly) unbound pool size.
 *
 * @author <a href="http://www.polymap.de">Falko Brutigam</a>
 */
public class UnboundPoolExecutor {

    private static Log log = LogFactory.getLog(UnboundPoolExecutor.class);

    public static int DEFAULT_THREAD_PRIORITY = Thread.NORM_PRIORITY - 1;

    public static int MAX_THREADS_PER_PROC = 32;

    public static ExecutorService newInstance() {
        final int procs = Runtime.getRuntime().availableProcessors();
        final int maxThreads = procs * MAX_THREADS_PER_PROC;

        // thread factory
        ThreadFactory threadFactory = new ThreadFactory() {
            volatile int threadNumber = 0;

            public Thread newThread(Runnable r) {
                String prefix = "polymap-";
                Thread t = new Thread(r, prefix + threadNumber++);
                t.setDaemon(false);
                t.setPriority(DEFAULT_THREAD_PRIORITY);
                return t;
            }
        };

        // thread pool
        ThreadPoolExecutor executor = new ThreadPoolExecutor(procs, maxThreads, 180L, TimeUnit.SECONDS,
                new SynchronousQueue<Runnable>(), threadFactory);

        // rejected? -> wait and try again
        executor.setRejectedExecutionHandler(new RejectedExecutionHandler() {
            Random rand = new Random();

            public void rejectedExecution(Runnable r, ThreadPoolExecutor _executor) {
                do {
                    try {
                        Thread.sleep(rand.nextInt(1000) + 100);
                    } catch (InterruptedException e) {
                    }
                } while (_executor.getActiveCount() >= maxThreads);

                _executor.execute(r);
            }
        });

        //executor.allowCoreThreadTimeOut( true );        
        return executor;
    }

}