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The Waikato Environment for Knowledge Analysis (WEKA), a machine
learning workbench. This version represents the developer version, the
"bleeding edge" of development, you could say. New functionality gets added
to this version.
/*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program 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 General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see m_TaskStatus = new Hashtable();
/** Is there a task running */
private boolean m_TaskRunning = false;
/** Clean up interval (in ms) */
protected static long CLEANUPTIMEOUT = 3600000;
/**
* Constructor
*
* @param hostName name of the host
* @exception RemoteException if something goes wrong
*/
public RemoteEngine(String hostName) throws RemoteException {
super();
m_HostName = hostName;
/*
* launch a clean-up thread. Will purge any failed or finished tasks still
* in the TaskStatus hashtable after an hour
*/
Thread cleanUpThread;
cleanUpThread = new Thread() {
@Override
public void run() {
while (true) {
try {
// sleep for a while
Thread.sleep(CLEANUPTIMEOUT);
} catch (InterruptedException ie) {
}
if (m_TaskStatus.size() > 0) {
purge();
} else {
System.err.println("RemoteEngine : purge - no tasks to check.");
}
}
}
};
cleanUpThread.setPriority(Thread.MIN_PRIORITY);
cleanUpThread.setDaemon(true);
cleanUpThread.start();
}
/**
* Takes a task object and queues it for execution
*
* @param t the Task object to execute
* @return an identifier for the Task that can be used when querying Task
* status
*/
@Override
public synchronized Object executeTask(Task t) throws RemoteException {
String taskId = "" + System.currentTimeMillis() + ":";
taskId += t.hashCode();
addTaskToQueue(t, taskId);
return taskId;
// return t.execute();
}
/**
* Returns status information on a particular task
*
* @param taskId the ID of the task to check
* @return a TaskStatusInfo encapsulating task status info
* @exception Exception if an error occurs
*/
@Override
public Object checkStatus(Object taskId) throws Exception {
TaskStatusInfo inf = m_TaskStatus.get(taskId);
if (inf == null) {
throw new Exception("RemoteEngine (" + m_HostName + ") : Task not found.");
}
TaskStatusInfo result = new TaskStatusInfo();
result.setExecutionStatus(inf.getExecutionStatus());
result.setStatusMessage(inf.getStatusMessage());
result.setTaskResult(inf.getTaskResult());
if (inf.getExecutionStatus() == TaskStatusInfo.FINISHED
|| inf.getExecutionStatus() == TaskStatusInfo.FAILED) {
System.err.println("Finished/failed Task id : " + taskId
+ " checked by client. Removing.");
inf.setTaskResult(null);
inf = null;
m_TaskStatus.remove(taskId);
}
inf = null;
return result;
}
/**
* Adds a new task to the queue.
*
* @param t a Task value to be added
* @param taskId the id of the task to be added
*/
private synchronized void addTaskToQueue(Task t, String taskId) {
TaskStatusInfo newTask = t.getTaskStatus();
if (newTask == null) {
newTask = new TaskStatusInfo();
}
m_TaskQueue.push(t);
m_TaskIdQueue.push(taskId);
newTask.setStatusMessage("RemoteEngine (" + m_HostName + ") : task "
+ taskId + " queued at postion: " + m_TaskQueue.size());
// add task status to HashTable
m_TaskStatus.put(taskId, newTask);
System.err.println("Task id : " + taskId + " Queued.");
if (m_TaskRunning == false) {
startTask();
}
}
/**
* Checks to see if there are any waiting tasks, and if no task is currently
* running starts a waiting task.
*/
private void startTask() {
if (m_TaskRunning == false && m_TaskQueue.size() > 0) {
Thread activeTaskThread;
activeTaskThread = new Thread() {
@Override
public void run() {
m_TaskRunning = true;
Task currentTask = (Task) m_TaskQueue.pop();
String taskId = (String) m_TaskIdQueue.pop();
TaskStatusInfo tsi = m_TaskStatus.get(taskId);
tsi.setExecutionStatus(TaskStatusInfo.PROCESSING);
tsi.setStatusMessage("RemoteEngine (" + m_HostName + ") : task "
+ taskId + " running...");
try {
System.err.println("Launching task id : " + taskId + "...");
currentTask.execute();
TaskStatusInfo runStatus = currentTask.getTaskStatus();
tsi.setExecutionStatus(runStatus.getExecutionStatus());
tsi.setStatusMessage("RemoteExperiment (" + m_HostName + ") "
+ runStatus.getStatusMessage());
tsi.setTaskResult(runStatus.getTaskResult());
} catch (Error er) {
// Object initialization can raise Error, which are not subclass of
// Exception
tsi.setExecutionStatus(TaskStatusInfo.FAILED);
if (er.getCause() instanceof java.security.AccessControlException) {
tsi.setStatusMessage("RemoteEngine (" + m_HostName
+ ") : security error, check remote policy file.");
System.err.println("Task id " + taskId
+ " Failed! Check remote policy file");
} else {
tsi.setStatusMessage("RemoteEngine (" + m_HostName
+ ") : unknown initialization error.");
System.err.println("Task id " + taskId
+ " Unknown initialization error");
er.printStackTrace();
System.err.println("Detailed message " + er.getMessage());
System.err.println("Detailed cause: " + er.getCause().toString());
}
} catch (Exception ex) {
tsi.setExecutionStatus(TaskStatusInfo.FAILED);
tsi.setStatusMessage("RemoteEngine (" + m_HostName + ") : "
+ ex.getMessage());
System.err.println("Task id " + taskId + " Failed, "
+ ex.getMessage());
} finally {
if (m_TaskStatus.size() == 0) {
purgeClasses();
}
m_TaskRunning = false;
// start any waiting tasks
startTask();
}
}
};
activeTaskThread.setPriority(Thread.MIN_PRIORITY);
activeTaskThread.start();
}
}
/**
* Attempts to purge class types from the virtual machine. May take some time
* as it relies on garbage collection
*/
private void purgeClasses() {
try {
// see if we can purge classes
ClassLoader prevCl = Thread.currentThread().getContextClassLoader();
ClassLoader urlCl = URLClassLoader.newInstance(new URL[] { new URL(
"file:.") }, prevCl);
Thread.currentThread().setContextClassLoader(urlCl);
} catch (Exception ex) {
ex.printStackTrace();
}
}
/**
* Checks the hash table for failed/finished tasks. Any that have been around
* for an @seeCLEANUPTIMEOUT or more are removed. Clients are expected to
* check on the status of their remote tasks. Checking on the status of a
* finished/failed task will remove it from the hash table, therefore any
* failed/finished tasks left lying around for more than an hour suggest that
* their client has died..
*
*/
private void purge() {
Enumeration keys = m_TaskStatus.keys();
long currentTime = System.currentTimeMillis();
System.err.println("RemoteEngine purge. Current time : " + currentTime);
while (keys.hasMoreElements()) {
String taskId = keys.nextElement();
System.err.print("Examining task id : " + taskId + "... ");
String timeString = taskId.substring(0, taskId.indexOf(':'));
long ts = Long.valueOf(timeString).longValue();
if (currentTime - ts > CLEANUPTIMEOUT) {
TaskStatusInfo tsi = m_TaskStatus.get(taskId);
if ((tsi != null)
&& (tsi.getExecutionStatus() == TaskStatusInfo.FINISHED || tsi
.getExecutionStatus() == TaskStatusInfo.FAILED)) {
System.err.println("\nTask id : " + taskId
+ " has gone stale. Removing.");
m_TaskStatus.remove(taskId);
tsi.setTaskResult(null);
tsi = null;
}
} else {
System.err.println("ok.");
}
}
if (m_TaskStatus.size() == 0) {
purgeClasses();
}
}
/**
* Returns the revision string.
*
* @return the revision
*/
@Override
public String getRevision() {
return RevisionUtils.extract("$Revision: 11247 $");
}
/**
* Main method. Gets address of the local host, creates a remote engine object
* and binds it in the RMI registry. If there is no RMI registry, then it
* tries to create one with default port 1099.
*
* @param args
*/
public static void main(String[] args) {
// make sure that all packages are loaded and available to
// the remote engines
weka.gui.GenericObjectEditor.determineClasses();
if (System.getSecurityManager() == null) {
System.setSecurityManager(new RMISecurityManager());
}
int port = 1099;
InetAddress localhost = null;
try {
localhost = InetAddress.getLocalHost();
System.err.println("Host name : " + localhost.getHostName());
} catch (Exception ex) {
ex.printStackTrace();
}
String name;
if (localhost != null) {
name = localhost.getHostName();
} else {
name = "localhost";
}
// get optional port
try {
String portOption = Utils.getOption("p", args);
if (!portOption.equals("")) {
port = Integer.parseInt(portOption);
}
} catch (Exception ex) {
System.err.println("Usage : -p ");
}
if (port != 1099) {
name = name + ":" + port;
}
name = "//" + name + "/RemoteEngine";
try {
Compute engine = new RemoteEngine(name);
try {
Naming.rebind(name, engine);
System.out.println("RemoteEngine bound in RMI registry");
} catch (RemoteException ex) {
// try to bootstrap a new registry
System.err.println("Attempting to start RMI registry on port " + port
+ "...");
java.rmi.registry.LocateRegistry.createRegistry(port);
Naming.bind(name, engine);
System.out.println("RemoteEngine bound in RMI registry");
}
} catch (Exception e) {
System.err.println("RemoteEngine exception: " + e.getMessage());
e.printStackTrace();
}
}
}