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

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

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/* 
 * polymap.org
 * Copyright 2012, 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.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.AtomicBoolean;
import java.util.concurrent.atomic.AtomicInteger;

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

/**
 * 
 *
 * @author <a href="http://www.polymap.de">Falko Brutigam</a>
 */
public class PolymapThreadPoolExecutor extends ThreadPoolExecutor implements ThreadFactory {

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

    public static PolymapThreadPoolExecutor newInstance() {
        // policy:
        //   - first: spawn up to proc*6 threads (stopped when idle for 180s)
        //   - then: queue 3 times more jobs (for faster feeding workers)
        //   - then: block until queue can take another job
        //   - and/or: expand corePoolSize (via bounds checkecker thread)
        int procs = Runtime.getRuntime().availableProcessors();
        final int nThreads = procs * 6;
        final int maxThreads = nThreads * 5;

        // Proper queue bound semantics but just half the task througput of
        // LinkedBlockingQueue in PerfTest
        // BlockingQueue queue = new ArrayBlockingQueue( nThreads * 5 );

        // Fastest. But unfortunatelle does not limit the number of queued
        // task, which might result in OOM or similar problem.
        final LinkedBlockingQueue queue = new LinkedBlockingQueue( /*nThreads * 3*/ );

        // Slowest queue. Does not feed the workers well if pool size exeeds.
        // BlockingQueue queue = new SynchronousQueue();

        final PolymapThreadPoolExecutor result = new PolymapThreadPoolExecutor(nThreads, maxThreads, 3 * 60, queue);
        result.allowCoreThreadTimeOut(true);

        // async queue bounds checker for unbound LinkedQueue
        Thread boundsChecker = new Thread("ThreadPoolBoundsChecker") {
            public void run() {
                int bound = result.getCorePoolSize() * 3;
                while (queue != null) {
                    try {
                        Thread.sleep(1000);
                        //                        log.info( "queued:" + queue.size() 
                        //                                + " - pool:" + result.getCorePoolSize() 
                        //                                + " - largest:" + result.getLargestPoolSize() 
                        //                                + " - completed:" + result.getCompletedTaskCount() );
                        // need more threads?
                        if (queue.size() > bound && result.getCorePoolSize() < maxThreads) {
                            int n = result.getCorePoolSize() + nThreads;
                            log.info("Thread Pool: increasing core pool size to: " + n);
                            result.setCorePoolSize(n);
                        }
                        // shrink down?
                        if (queue.isEmpty() && result.getActiveCount() == 0
                                && result.getCorePoolSize() > nThreads) {
                            log.info("Thread Pool: decreasing core pool size to: " + nThreads);
                            result.setCorePoolSize(nThreads);
                        }
                    } catch (Throwable e) {
                        log.warn("", e);
                    }
                }
            }
        };
        boundsChecker.setPriority(Thread.MIN_PRIORITY);
        boundsChecker.start();

        return result;
    }

    // instance *******************************************

    private final AtomicInteger threadNumber = new AtomicInteger(1);

    private static AtomicBoolean queueFull = new AtomicBoolean();

    public PolymapThreadPoolExecutor(int minPoolSize, int maxPoolSize, int keepAliveSecs, BlockingQueue queue) {
        super(minPoolSize, maxPoolSize, keepAliveSecs, TimeUnit.SECONDS, queue);

        // thread factory
        setThreadFactory(this);

        // rejected? -> wait and try again
        setRejectedExecutionHandler(new RejectedExecutionHandler() {
            public void rejectedExecution(Runnable r, ThreadPoolExecutor executor) {
                //log.warn( "Unable to queue task: " + r );
                // wait (a long time) and try again (until StackOverflow)
                synchronized (queueFull) {
                    queueFull.set(true);
                    try {
                        queueFull.wait(1000);
                    } catch (InterruptedException e) {
                    }
                }
                executor.execute(r);
            }
        });

    }

    protected void afterExecute(Runnable r, Throwable t) {
        super.afterExecute(r, t);
        if (queueFull.get()) {
            synchronized (queueFull) {
                queueFull.set(false);
                queueFull.notifyAll();
            }
        }
    }

    public Thread newThread(Runnable r) {
        String prefix = "polymap-worker-";
        Thread t = new Thread(r, prefix + threadNumber.getAndIncrement());
        t.setDaemon(false);
        t.setPriority(Thread.NORM_PRIORITY - 1);
        return t;
    }

}