/*
* JBoss, Home of Professional Open Source
* Copyright 2005, JBoss Inc., and individual contributors as indicated
* by the @authors tag. See the copyright.txt in the distribution for a
* full listing of individual contributors.
*
* 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.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this software; if not, write to the Free
* Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
* 02110-1301 USA, or see the FSF site: http://www.fsf.org.
*/
package org.jboss.util.threadpool;
import java.security.AccessController;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Map;
import java.util.PriorityQueue;
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.jboss.logging.Logger;
import org.jboss.util.collection.WeakValueHashMap;
import org.jboss.util.loading.ClassLoaderSource;
import org.jboss.util.loading.ContextClassLoaderSwitcher;
/**
* A basic thread pool.
* TODO: this port to jdk concurrent still needs to be tested.
*
* @author <a href="mailto:adrian@jboss.org">Adrian Brock</a>
* @author Scott.Stark@jboss.org
* @version $Revision: 2789 $
*/
@SuppressWarnings("unchecked")
public class BasicThreadPool implements ThreadPool, BasicThreadPoolMBean
{
// Constants -----------------------------------------------------
/** The jboss thread group */
private static final ThreadGroup JBOSS_THREAD_GROUP = new ThreadGroup("JBoss Pooled Threads");
/** The thread groups */
private static final Map threadGroups = Collections.synchronizedMap(new WeakValueHashMap());
/** The internal pool number */
private static final AtomicInteger lastPoolNumber = new AtomicInteger(0);
private static Logger log = Logger.getLogger(BasicThreadPool.class);
// Attributes ----------------------------------------------------
/** The thread pool name */
private String name;
/** The internal pool number */
private int poolNumber;
/** The blocking mode */
private BlockingMode blockingMode = BlockingMode.ABORT;
/** The pooled executor */
private ThreadPoolExecutor executor;
/** The queue */
private LinkedBlockingQueue queue;
/** The thread group */
private ThreadGroup threadGroup;
/** Source for the thread contrext classloader to assign to threads */
private ClassLoaderSource classLoaderSource;
private ContextClassLoaderSwitcher classLoaderSwitcher;
/** The last thread number */
private AtomicInteger lastThreadNumber = new AtomicInteger(0);
/** Has the pool been stopped? */
private AtomicBoolean stopped = new AtomicBoolean(false);
/** The Heap<TimeoutInfo> of tasks ordered by their completion timeout */
private PriorityQueue<TimeoutInfo> tasksWithTimeouts = new PriorityQueue<TimeoutInfo>(13);
/** The task completion timeout monitor runnable */
private TimeoutMonitor timeoutTask;
/** The trace level logging flag */
private boolean trace;
// Static --------------------------------------------------------
// Constructors --------------------------------------------------
/**
* Create a new thread pool
*/
public BasicThreadPool()
{
this("ThreadPool");
}
/**
* Create a new thread pool with a default queue size of 1024, max pool
* size of 100, min pool size of 4, and a keep alive of 60 seconds.
*
* @param name the pool name
*/
public BasicThreadPool(String name)
{
this(name, JBOSS_THREAD_GROUP);
}
/**
* Create a new thread pool with a default queue size of 1024, max pool
* size of 100, min pool size of 4, and a keep alive of 60 seconds.
*
* @param name the pool name
* @param threadGroup threadGroup
*/
public BasicThreadPool(String name, ThreadGroup threadGroup)
{
trace = log.isTraceEnabled();
ThreadFactory factory = new ThreadPoolThreadFactory();
queue = new LinkedBlockingQueue(1024);
executor = new RestoreTCCLThreadPoolExecutor(4, 4, 60, TimeUnit.SECONDS, queue);
executor.setThreadFactory(factory);
executor.setRejectedExecutionHandler(new ThreadPoolExecutor.AbortPolicy());
poolNumber = lastPoolNumber.incrementAndGet();
setName(name);
this.threadGroup = threadGroup;
}
// Public --------------------------------------------------------
// ThreadPool ----------------------------------------------------
public void stop(boolean immediate)
{
log.debug("stop, immediate="+immediate);
stopped.set(true);
if (immediate)
executor.shutdownNow();
else
executor.shutdown();
}
public void waitForTasks() throws InterruptedException
{
executor.awaitTermination(Long.MAX_VALUE, TimeUnit.MILLISECONDS);
}
public void waitForTasks(long maxWaitTime) throws InterruptedException
{
executor.awaitTermination(maxWaitTime, TimeUnit.MILLISECONDS);
}
public void runTaskWrapper(TaskWrapper wrapper)
{
if( trace )
log.trace("runTaskWrapper, wrapper="+wrapper);
if (stopped.get())
{
wrapper.rejectTask(new ThreadPoolStoppedException("Thread pool has been stopped"));
return;
}
wrapper.acceptTask();
long completionTimeout = wrapper.getTaskCompletionTimeout();
TimeoutInfo info = null;
if( completionTimeout > 0 )
{
checkTimeoutMonitor();
// Install the task in the
info = new TimeoutInfo(wrapper, completionTimeout);
tasksWithTimeouts.add(info);
}
int waitType = wrapper.getTaskWaitType();
switch (waitType)
{
case Task.WAIT_FOR_COMPLETE:
{
executeOnThread(wrapper);
break;
}
default:
{
execute(wrapper);
}
}
waitForTask(wrapper);
}
public void runTask(Task task)
{
BasicTaskWrapper wrapper = new BasicTaskWrapper(task);
runTaskWrapper(wrapper);
}
public void run(Runnable runnable)
{
run(runnable, 0, 0);
}
public void run(Runnable runnable, long startTimeout, long completeTimeout)
{
RunnableTaskWrapper wrapper = new RunnableTaskWrapper(runnable, startTimeout, completeTimeout);
runTaskWrapper(wrapper);
}
public ThreadGroup getThreadGroup()
{
return threadGroup;
}
// ThreadPoolMBean implementation --------------------------------
public String getName()
{
return name;
}
public void setName(String name)
{
this.name = name;
}
public int getPoolNumber()
{
return poolNumber;
}
public String getThreadGroupName()
{
return threadGroup.getName();
}
public void setThreadGroupName(String threadGroupName)
{
ThreadGroup group;
synchronized(threadGroups)
{
group = (ThreadGroup) threadGroups.get(threadGroupName);
if (group == null)
{
group = new ThreadGroup(JBOSS_THREAD_GROUP, threadGroupName);
threadGroups.put(threadGroupName, group);
}
}
threadGroup = group;
}
public int getQueueSize()
{
return queue.size();
}
public int getMaximumQueueSize()
{
int maxSize = queue.remainingCapacity() + queue.size();
return maxSize;
}
/**
* This resets the work queue capacity. This requires recreating the
* work queue and ThreadPoolExecutor, so this needs to be called
* before doing any work with the pool.
*
* @param size new work queue capacity
*/
public void setMaximumQueueSize(int size)
{
// Reset the executor work queue
ArrayList tmp = new ArrayList();
queue.drainTo(tmp);
queue = new LinkedBlockingQueue(size);
queue.addAll(tmp);
ThreadFactory tf = executor.getThreadFactory();
RejectedExecutionHandler handler = executor.getRejectedExecutionHandler();
long keepAlive = executor.getKeepAliveTime(TimeUnit.SECONDS);
int cs = executor.getCorePoolSize();
int mcs = executor.getMaximumPoolSize();
executor = new ThreadPoolExecutor(cs, mcs, keepAlive, TimeUnit.SECONDS, queue);
executor.setThreadFactory(tf);
executor.setRejectedExecutionHandler(handler);
}
public int getPoolSize()
{
return executor.getPoolSize();
}
public int getMinimumPoolSize()
{
return executor.getCorePoolSize();
}
public void setMinimumPoolSize(int size)
{
synchronized (executor)
{
// Don't let the min size > max size
if (executor.getMaximumPoolSize() < size)
{
executor.setCorePoolSize(size);
executor.setMaximumPoolSize(size);
}
}
}
public int getMaximumPoolSize()
{
return executor.getMaximumPoolSize();
}
public void setMaximumPoolSize(int size)
{
synchronized (executor)
{
executor.setCorePoolSize(size);
executor.setMaximumPoolSize(size);
}
}
public long getKeepAliveTime()
{
return executor.getKeepAliveTime(TimeUnit.MILLISECONDS);
}
public void setKeepAliveTime(long time)
{
executor.setKeepAliveTime(time, TimeUnit.MILLISECONDS);
}
public BlockingMode getBlockingMode()
{
return blockingMode;
}
public void setBlockingMode(BlockingMode mode)
{
blockingMode = mode;
if( blockingMode == BlockingMode.RUN )
{
executor.setRejectedExecutionHandler(new ThreadPoolExecutor.CallerRunsPolicy());
}
else if( blockingMode == BlockingMode.WAIT )
{
executor.setRejectedExecutionHandler(new ThreadPoolExecutor.CallerRunsPolicy());
}
else if( blockingMode == BlockingMode.DISCARD )
{
executor.setRejectedExecutionHandler(new ThreadPoolExecutor.DiscardPolicy());
}
else if( blockingMode == BlockingMode.DISCARD_OLDEST )
{
executor.setRejectedExecutionHandler(new ThreadPoolExecutor.DiscardOldestPolicy());
}
else if( blockingMode == BlockingMode.ABORT )
{
executor.setRejectedExecutionHandler(new ThreadPoolExecutor.AbortPolicy());
}
else
{
throw new IllegalArgumentException("Failed to recognize mode: "+mode);
}
}
/**
* For backward compatibility with the previous string based mode
* @param name - the string form of the mode enum
*/
public void setBlockingMode(String name)
{
blockingMode = BlockingMode.toBlockingMode(name);
if( blockingMode == null )
blockingMode = BlockingMode.ABORT;
}
/**
* For backward compatibility with the previous string based mode
* This is needed for microcontainer as it gets confused with overloaded
* setters.
* @param name - the string form of the mode enum
*/
public void setBlockingModeString(String name)
{
blockingMode = BlockingMode.toBlockingMode(name);
if( blockingMode == null )
blockingMode = BlockingMode.ABORT;
}
public ClassLoaderSource getClassLoaderSource()
{
return classLoaderSource;
}
public void setClassLoaderSource(ClassLoaderSource classLoaderSource)
{
if (classLoaderSource == null)
{
this.classLoaderSource = null;
this.classLoaderSwitcher = null;
}
else if (classLoaderSwitcher == null)
{
try
{
this.classLoaderSwitcher = (ContextClassLoaderSwitcher) AccessController.doPrivileged(ContextClassLoaderSwitcher.INSTANTIATOR);
this.classLoaderSource = classLoaderSource;
}
catch (SecurityException e)
{
log.error("Cannot manage context classloader for pool threads; " +
"Do not have setContextClassLoader permission");
}
}
else
{
this.classLoaderSource = classLoaderSource;
}
}
public ThreadPool getInstance()
{
return this;
}
public void stop()
{
stop(false);
}
// Object overrides ----------------------------------------------
public String toString()
{
return name + '(' + poolNumber + ')';
}
// Package protected ---------------------------------------------
// Protected -----------------------------------------------------
/**
* Execute a task on the same thread
*
* @param wrapper the task wrapper
*/
protected void executeOnThread(TaskWrapper wrapper)
{
if( trace )
log.trace("executeOnThread, wrapper="+wrapper);
wrapper.run();
}
/**
* Execute a task
*
* @param wrapper the task wrapper
*/
protected void execute(TaskWrapper wrapper)
{
if( trace )
log.trace("execute, wrapper="+wrapper);
try
{
executor.execute(wrapper);
}
catch (Throwable t)
{
wrapper.rejectTask(new ThreadPoolFullException("Error scheduling work: " + wrapper, t));
}
}
/**
* Wait for a task
*
* @param wrapper the task wrapper
*/
protected void waitForTask(TaskWrapper wrapper)
{
wrapper.waitForTask();
}
/**
* Used to lazily create the task completion timeout thread and monitor
*/
protected synchronized void checkTimeoutMonitor()
{
if( timeoutTask == null )
timeoutTask = new TimeoutMonitor(name, log);
}
protected TimeoutInfo getNextTimeout()
{
TimeoutInfo info = null;
if(this.tasksWithTimeouts.isEmpty() == false)
{
info = this.tasksWithTimeouts.remove();
}
return info;
}
protected void setDefaultThreadContextClassLoader(Thread thread)
{
if (classLoaderSwitcher != null)
{
ClassLoader cl = classLoaderSource == null ? null : classLoaderSource.getClassLoader();
classLoaderSwitcher.setContextClassLoader(thread, cl);
}
}
// Private -------------------------------------------------------
// Inner classes -------------------------------------------------
/**
* A factory for threads
*/
private class ThreadPoolThreadFactory implements ThreadFactory
{
public Thread newThread(Runnable runnable)
{
String threadName = BasicThreadPool.this.toString() + "-" + lastThreadNumber.incrementAndGet();
Thread thread = new Thread(threadGroup, runnable, threadName);
thread.setDaemon(true);
BasicThreadPool.this.setDefaultThreadContextClassLoader(thread);
return thread;
}
}
private class RestoreTCCLThreadPoolExecutor extends ThreadPoolExecutor
{
public RestoreTCCLThreadPoolExecutor(int corePoolSize, int maximumPoolSize,
long keepAliveTime, TimeUnit unit,
BlockingQueue<Runnable> workQueue)
{
super(corePoolSize, maximumPoolSize, keepAliveTime, unit, workQueue);
}
@Override
protected void afterExecute(Runnable r, Throwable t)
{
try
{
super.afterExecute(r, t);
}
finally
{
BasicThreadPool.this.setDefaultThreadContextClassLoader(Thread.currentThread());
}
}
}
/** An encapsulation of a task and its completion timeout
*/
private static class TimeoutInfo implements Comparable
{
long start;
long timeoutMS;
TaskWrapper wrapper;
boolean firstStop;
TimeoutInfo(TaskWrapper wrapper, long timeout)
{
this.start = System.currentTimeMillis();
this.timeoutMS = start + timeout;
this.wrapper = wrapper;
}
public void setTimeout(long timeout)
{
this.start = System.currentTimeMillis();
this.timeoutMS = start + timeout;
}
/** Order TimeoutInfo based on the timestamp at which the task needs to
* be completed by.
* @param o a TimeoutInfo
* @return the diff between this timeoutMS and the argument timeoutMS
*/
public int compareTo(Object o)
{
TimeoutInfo ti = (TimeoutInfo) o;
long to0 = timeoutMS;
long to1 = ti.timeoutMS;
int diff = (int) (to0 - to1);
return diff;
}
TaskWrapper getTaskWrapper()
{
return wrapper;
}
public long getTaskCompletionTimeout()
{
return wrapper.getTaskCompletionTimeout();
}
/** Get the time remaining to the complete timeout timestamp in MS.
* @param now - the current System.currentTimeMillis value
* @return the time remaining to the complete timeout timestamp in MS.
*/
public long getTaskCompletionTimeout(long now)
{
return timeoutMS - now;
}
/** Invoke stopTask on the wrapper and indicate whether this was the first
* time the task has been notified to stop.
* @return true if this is the first stopTask, false on the second.
*/
public boolean stopTask()
{
wrapper.stopTask();
boolean wasFirstStop = firstStop == false;
firstStop = true;
return wasFirstStop;
}
}
/**
* The monitor runnable which validates that threads are completing within
* the task completion timeout limits.
*/
private class TimeoutMonitor implements Runnable
{
@SuppressWarnings("hiding")
final Logger log;
TimeoutMonitor(String name, Logger log)
{
this.log = log;
Thread t = new Thread(this, name+" TimeoutMonitor");
t.setDaemon(true);
t.start();
}
/** The monitor thread loops until the pool is shutdown. It waits for
* tasks with completion timeouts and sleeps until the next completion
* timeout and then interrupts the associated task thread, and invokes
* stopTask on the TaskWrapper. A new timeout check is then inserted with
* a 1 second timeout to validate that the TaskWrapper has exited the
* run method. If it has not, then the associated task thread is stopped
* using the deprecated Thread.stop method since this is the only way to
* abort a thread that is in spin loop for example.
*
* @todo this is not responsive to new tasks with timeouts smaller than
* the current shortest completion expiration. We probably should interrupt
* the thread on each insertion into the timeout heap to ensure better
* responsiveness.
*/
public void run()
{
boolean isStopped = stopped.get();
while( isStopped == false )
{
boolean trace = log.isTraceEnabled();
try
{
TimeoutInfo info = getNextTimeout();
if( info != null )
{
long now = System.currentTimeMillis();
long timeToTimeout = info.getTaskCompletionTimeout(now);
if( timeToTimeout > 0 )
{
if( trace )
{
log.trace("Will check wrapper="+info.getTaskWrapper()
+" after "+timeToTimeout);
}
Thread.sleep(timeToTimeout);
}
// Check the status of the task
TaskWrapper wrapper = info.getTaskWrapper();
if( wrapper.isComplete() == false )
{
if( trace )
log.trace("Failed completion check for wrapper="+wrapper);
if( info.stopTask() == true )
{
// Requeue the TimeoutInfo to see that the task exits run
info.setTimeout(1000);
tasksWithTimeouts.add(info);
if( trace )
log.trace("Rescheduled completion check for wrapper="+wrapper);
}
}
}
else
{
Thread.sleep(1000);
}
}
catch(InterruptedException e)
{
log.debug("Timeout monitor has been interrupted", e);
}
catch(Throwable e)
{
log.debug("Timeout monitor saw unexpected error", e);
}
isStopped = stopped.get();
}
}
}
}