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Jetty example source code file (BoundedThreadPool.java)
The Jetty BoundedThreadPool.java source code// ======================================================================== // Copyright 2004-2005 Mort Bay Consulting Pty. Ltd. // ------------------------------------------------------------------------ // 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.mortbay.thread; import java.io.Serializable; import java.util.ArrayList; import java.util.HashSet; import java.util.Iterator; import java.util.LinkedList; import java.util.List; import java.util.Set; import org.mortbay.component.AbstractLifeCycle; import org.mortbay.log.Log; /* ------------------------------------------------------------ */ /** A pool of threads. * <p> * Avoids the expense of thread creation by pooling threads after * their run methods exit for reuse. * <p> * If the maximum pool size is reached, jobs wait for a free thread. * By default there is no maximum pool size. Idle threads timeout * and terminate until the minimum number of threads are running. * <p> * @author Greg Wilkins <gregw@mortbay.com> * @author Juancarlo Anez <juancarlo@modelistica.com> */ public class BoundedThreadPool extends AbstractLifeCycle implements Serializable, ThreadPool { private static int __id; private boolean _daemon; private int _id; private List _idle; private final Object _lock = new Object(); private final Object _joinLock = new Object(); private long _lastShrink; private int _maxIdleTimeMs=60000; private int _maxThreads=255; private int _minThreads=1; private String _name; private List _queue; private Set _threads; private boolean _warned=false; int _lowThreads=0; int _priority= Thread.NORM_PRIORITY; /* ------------------------------------------------------------------- */ /* Construct */ public BoundedThreadPool() { _name="btpool"+__id++; } /* ------------------------------------------------------------ */ /** Run job. * @return true */ public boolean dispatch(Runnable job) { synchronized(_lock) { if (!isRunning() || job==null) return false; // Are there no threads available? int idle=_idle.size(); if (idle>0) { PoolThread thread=(PoolThread)_idle.remove(idle-1); thread.dispatch(job); } else { // Are we at max size? if (_threads.size()<_maxThreads) { // No - create a new thread! newThread(job); } else { if (!_warned) { _warned=true; Log.debug("Out of threads for {}",this); } _queue.add(job); } } } return true; } /* ------------------------------------------------------------ */ /** Get the number of idle threads in the pool. * @see #getThreads * @return Number of threads */ public int getIdleThreads() { return _idle==null?0:_idle.size(); } /* ------------------------------------------------------------ */ /** * @return low resource threads threshhold */ public int getLowThreads() { return _lowThreads; } /* ------------------------------------------------------------ */ /** Get the maximum thread idle time. * Delegated to the named or anonymous Pool. * @see #setMaxIdleTimeMs * @return Max idle time in ms. */ public int getMaxIdleTimeMs() { return _maxIdleTimeMs; } /* ------------------------------------------------------------ */ /** Set the maximum number of threads. * Delegated to the named or anonymous Pool. * @see #setMaxThreads * @return maximum number of threads. */ public int getMaxThreads() { return _maxThreads; } /* ------------------------------------------------------------ */ /** Get the minimum number of threads. * Delegated to the named or anonymous Pool. * @see #setMinThreads * @return minimum number of threads. */ public int getMinThreads() { return _minThreads; } /* ------------------------------------------------------------ */ /** * @return The name of the BoundedThreadPool. */ public String getName() { return _name; } /* ------------------------------------------------------------ */ /** Get the number of threads in the pool. * @see #getIdleThreads * @return Number of threads */ public int getThreads() { return _threads.size(); } /* ------------------------------------------------------------ */ /** Get the priority of the pool threads. * @return the priority of the pool threads. */ public int getThreadsPriority() { return _priority; } /* ------------------------------------------------------------ */ public int getQueueSize() { synchronized(_lock) { return _queue.size(); } } /* ------------------------------------------------------------ */ /** * Delegated to the named or anonymous Pool. */ public boolean isDaemon() { return _daemon; } /* ------------------------------------------------------------ */ public boolean isLowOnThreads() { synchronized(_lock) { // maybe make this volatile? return _queue.size()>_lowThreads; } } /* ------------------------------------------------------------ */ public void join() throws InterruptedException { synchronized (_joinLock) { while (isRunning()) _joinLock.wait(); } // TODO remove this semi busy loop! while (isStopping()) Thread.sleep(10); } /* ------------------------------------------------------------ */ /** * Delegated to the named or anonymous Pool. */ public void setDaemon(boolean daemon) { _daemon=daemon; } /* ------------------------------------------------------------ */ /** * @param lowThreads low resource threads threshhold */ public void setLowThreads(int lowThreads) { _lowThreads = lowThreads; } /* ------------------------------------------------------------ */ /** Set the maximum thread idle time. * Threads that are idle for longer than this period may be * stopped. * Delegated to the named or anonymous Pool. * @see #getMaxIdleTimeMs * @param maxIdleTimeMs Max idle time in ms. */ public void setMaxIdleTimeMs(int maxIdleTimeMs) { _maxIdleTimeMs=maxIdleTimeMs; } /* ------------------------------------------------------------ */ /** Set the maximum number of threads. * Delegated to the named or anonymous Pool. * @see #getMaxThreads * @param maxThreads maximum number of threads. */ public void setMaxThreads(int maxThreads) { if (isStarted() && maxThreads<_minThreads) throw new IllegalArgumentException("!minThreads<maxThreads"); _maxThreads=maxThreads; } /* ------------------------------------------------------------ */ /** Set the minimum number of threads. * Delegated to the named or anonymous Pool. * @see #getMinThreads * @param minThreads minimum number of threads */ public void setMinThreads(int minThreads) { if (isStarted() && (minThreads<=0 || minThreads>_maxThreads)) throw new IllegalArgumentException("!0<=minThreads |
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