edu.rit.pj.cluster
Class JobBackend

java.lang.Object
  edu.rit.pj.cluster.JobBackend

All Implemented Interfaces:

JobBackendRef, Runnable

public class JobBackend
extends Object
implements Runnable, JobBackendRef

Class JobBackend is the main program for a job backend process in the PJ cluster middleware. The job backend process is launched by an SSH remote login from the job frontend process (class JobFrontend).

The command line for the job backend main program is:

java edu.rit.pj.cluster.JobBackend username jobnum K rank hasFrontendComm frontendHost frontendPort backendHost
username = User name
jobnum = Job number
K = Number of backend processes (>= 1)
rank = Rank of this backend process (0 .. K-1)
hasFrontendComm = Whether the frontend communicator exists (true or false)
frontendHost = Job frontend's middleware channel group host name
frontendPort = Job frontend's middleware channel group port number
backendHost = Job backend's middleware channel group host name

Method Summary

void	cancelJob(JobFrontendRef theJobFrontend, String errmsg) Cancel the job.
void	close() Close communication with this Job Backend.
void	commenceJob(JobFrontendRef theJobFrontend, InetSocketAddress[] middlewareAddress, InetSocketAddress[] worldAddress, InetSocketAddress[] frontendAddress, Properties properties, String mainClassName, String[] args) Commence the job.
String[]	getArgs() Obtain this job's command line arguments.
String	getBackendHost() Obtain the backend host name on which this job is running.
ClassLoader	getClassLoader() Obtain this job's backend class loader.
BackendFileReader	getFileReader() Obtain this job's backend file reader.
BackendFileWriter	getFileWriter() Obtain this job's backend file writer.
InetSocketAddress[]	getFrontendAddress() Obtain this job's array of hosts/ports for the frontend communicator.
ChannelGroup	getFrontendChannelGroup() Obtain this job's frontend communicator channel group.
static JobBackend	getJobBackend() Obtain the Job Backend object.
int	getJobNumber() Obtain this job's job number.
int	getK() Obtain the number of backend processes in this job.
String	getMainClassName() Obtain this job's main class name.
Properties	getProperties() Obtain this job's Java system properties.
int	getRank() Obtain the rank of this backend process in this job.
String	getUserName() Obtain this job's user name.
InetSocketAddress[]	getWorldAddress() Obtain this job's array of hosts/ports for the world communicator.
ChannelGroup	getWorldChannelGroup() Obtain this job's world communicator channel group.
boolean	hasFrontendCommunicator() Determine whether the frontend communicator exists in this job.
void	inputFileCloseResult(JobFrontendRef theJobFrontend, int ffd, IOException exc) Report the result of closing the given input file.
void	inputFileOpenResult(JobFrontendRef theJobFrontend, int bfd, int ffd, IOException exc) Report the result of opening the given input file.
void	inputFileReadResult(JobFrontendRef theJobFrontend, int ffd, byte[] buf, int len, IOException exc) Report the result of reading the given input file.
void	inputFileSkipResult(JobFrontendRef theJobFrontend, int ffd, long len, IOException exc) Report the result of skipping the given input file.
void	jobFinished(JobFrontendRef theJobFrontend) Report that the job finished.
static void	main(String[] args) Job Backend main program.
void	outputFileCloseResult(JobFrontendRef theJobFrontend, int ffd, IOException exc) Report the result of closing the given output file.
void	outputFileFlushResult(JobFrontendRef theJobFrontend, int ffd, IOException exc) Report the result of flushing the given output file.
void	outputFileOpenResult(JobFrontendRef theJobFrontend, int bfd, int ffd, IOException exc) Report the result of opening the given output file.
void	outputFileWriteResult(JobFrontendRef theJobFrontend, int ffd, IOException exc) Report the result of writing the given output file.
void	renewLease(JobFrontendRef theJobFrontend) Renew the lease on the job.
void	reportResource(JobFrontendRef theJobFrontend, String resourceName, byte[] content) Report the content for a previously-requested resource.
void	reportResource(JobFrontendRef theJobFrontend, String resourceName, ByteSequence content) Report the content for a previously-requested resource.
void	run() Run this Job Backend.
void	setComment(String comment) Set the comment string for this job backend process.
void	waitForCommence() Wait until this job commences.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Method Detail

run

public void run()

Run this Job Backend.

Specified by:

run in interface Runnable

cancelJob

public void cancelJob(JobFrontendRef theJobFrontend,
                      String errmsg)
               throws IOException

Cancel the job.

Specified by:

cancelJob in interface JobBackendRef

Parameters:

theJobFrontend - Job Frontend that is calling this method.

errmsg - Error message string.

Throws:

IOException - Thrown if an I/O error occurred.

commenceJob

public void commenceJob(JobFrontendRef theJobFrontend,
                        InetSocketAddress[] middlewareAddress,
                        InetSocketAddress[] worldAddress,
                        InetSocketAddress[] frontendAddress,
                        Properties properties,
                        String mainClassName,
                        String[] args)
                 throws IOException

Commence the job.

Specified by:

commenceJob in interface JobBackendRef

Parameters:

theJobFrontend - Job Frontend that is calling this method.

middlewareAddress - Array of hosts/ports for middleware messages. The first K elements are for the job backend processes in rank order, the K+1st element is for the job frontend process. If the

worldAddress - Array of hosts/ports for the world communicator. The K elements are for the job backend processes in rank order.

frontendAddress - Array of hosts/ports for the frontend communicator. The first K elements are for the job backend processes in rank order, the K+1st element is for the job frontend process. If the frontend communicator does not exist, frontendAddress is null.

properties - Java system properties.

mainClassName - Fully qualified class name of the Java main program class to execute.

args - Array of 0 or more Java command line arguments.

Throws:

IOException - Thrown if an I/O error occurred.

jobFinished

public void jobFinished(JobFrontendRef theJobFrontend)
                 throws IOException

Report that the job finished.

Specified by:

jobFinished in interface JobBackendRef

Parameters:

theJobFrontend - Job frontend that is calling this method.

Throws:

IOException - Thrown if an I/O error occurred.

renewLease

public void renewLease(JobFrontendRef theJobFrontend)
                throws IOException

Renew the lease on the job.

Specified by:

renewLease in interface JobBackendRef

Parameters:

theJobFrontend - Job Frontend that is calling this method.

Throws:

IOException - Thrown if an I/O error occurred.

reportResource

public void reportResource(JobFrontendRef theJobFrontend,
                           String resourceName,
                           byte[] content)
                    throws IOException

Report the content for a previously-requested resource.

Specified by:

reportResource in interface JobBackendRef

Parameters:

theJobFrontend - Job Frontend that is calling this method.

resourceName - Resource name.

content - Resource content, or null if resource not found.

Throws:

IOException - Thrown if an I/O error occurred.

reportResource

public void reportResource(JobFrontendRef theJobFrontend,
                           String resourceName,
                           ByteSequence content)
                    throws IOException

Report the content for a previously-requested resource.

Specified by:

reportResource in interface JobBackendRef

Parameters:

theJobFrontend - Job Frontend that is calling this method.

resourceName - Resource name.

content - Resource content, or null if resource not found.

Throws:

IOException - Thrown if an I/O error occurred.

outputFileOpenResult

public void outputFileOpenResult(JobFrontendRef theJobFrontend,
                                 int bfd,
                                 int ffd,
                                 IOException exc)
                          throws IOException

Report the result of opening the given output file.

Specified by:

outputFileOpenResult in interface JobBackendRef

Parameters:

theJobFrontend - Job Frontend that is calling this method.

bfd - Backend file descriptor.

ffd - Frontend file descriptor if success.

exc - Null if success, exception if failure.

Throws:

IOException - Thrown if an I/O error occurred.

outputFileWriteResult

public void outputFileWriteResult(JobFrontendRef theJobFrontend,
                                  int ffd,
                                  IOException exc)
                           throws IOException

Report the result of writing the given output file.

Specified by:

outputFileWriteResult in interface JobBackendRef

Parameters:

theJobFrontend - Job Frontend that is calling this method.

ffd - Frontend file descriptor.

exc - Null if success, exception if failure.

Throws:

IOException - Thrown if an I/O error occurred.

outputFileFlushResult

public void outputFileFlushResult(JobFrontendRef theJobFrontend,
                                  int ffd,
                                  IOException exc)
                           throws IOException

Report the result of flushing the given output file.

Specified by:

outputFileFlushResult in interface JobBackendRef

Parameters:

theJobFrontend - Job Frontend that is calling this method.

ffd - Frontend file descriptor.

exc - Null if success, exception if failure.

Throws:

IOException - Thrown if an I/O error occurred.

outputFileCloseResult

public void outputFileCloseResult(JobFrontendRef theJobFrontend,
                                  int ffd,
                                  IOException exc)
                           throws IOException

Report the result of closing the given output file.

Specified by:

outputFileCloseResult in interface JobBackendRef

Parameters:

theJobFrontend - Job Frontend that is calling this method.

ffd - Frontend file descriptor.

exc - Null if success, exception if failure.

Throws:

IOException - Thrown if an I/O error occurred.

inputFileOpenResult

public void inputFileOpenResult(JobFrontendRef theJobFrontend,
                                int bfd,
                                int ffd,
                                IOException exc)
                         throws IOException

Report the result of opening the given input file.

Specified by:

inputFileOpenResult in interface JobBackendRef

Parameters:

theJobFrontend - Job Frontend that is calling this method.

bfd - Backend file descriptor.

ffd - Frontend file descriptor if success.

exc - Null if success, exception if failure.

Throws:

IOException - Thrown if an I/O error occurred.

inputFileReadResult

public void inputFileReadResult(JobFrontendRef theJobFrontend,
                                int ffd,
                                byte[] buf,
                                int len,
                                IOException exc)
                         throws IOException

Report the result of reading the given input file.

Specified by:

inputFileReadResult in interface JobBackendRef

Parameters:

theJobFrontend - Job Frontend that is calling this method.

ffd - Frontend file descriptor.

buf - Bytes read.

len - Number of bytes read, or -1 if EOF.

exc - Null if success, exception if failure.

Throws:

IOException - Thrown if an I/O error occurred.

inputFileSkipResult

public void inputFileSkipResult(JobFrontendRef theJobFrontend,
                                int ffd,
                                long len,
                                IOException exc)
                         throws IOException

Report the result of skipping the given input file.

Specified by:

inputFileSkipResult in interface JobBackendRef

Parameters:

theJobFrontend - Job Frontend that is calling this method.

ffd - Frontend file descriptor.

len - Number of bytes skipped.

exc - Null if success, exception if failure.

Throws:

IOException - Thrown if an I/O error occurred.

inputFileCloseResult

public void inputFileCloseResult(JobFrontendRef theJobFrontend,
                                 int ffd,
                                 IOException exc)
                          throws IOException

Report the result of closing the given input file.

Specified by:

inputFileCloseResult in interface JobBackendRef

Parameters:

theJobFrontend - Job Frontend that is calling this method.

ffd - Frontend file descriptor.

exc - Null if success, exception if failure.

Throws:

IOException - Thrown if an I/O error occurred.

close

public void close()

Close communication with this Job Backend.

Specified by:

close in interface JobBackendRef

getUserName

public String getUserName()

Obtain this job's user name.

Returns:

User name.

getJobNumber

public int getJobNumber()

Obtain this job's job number.

Returns:

Job number.

getK

public int getK()

Obtain the number of backend processes in this job.

Returns:

K, the number of backend processes.

getRank

public int getRank()

Obtain the rank of this backend process in this job.

Returns:

Rank.

getBackendHost

public String getBackendHost()

Obtain the backend host name on which this job is running.

Returns:

Host name.

hasFrontendCommunicator

public boolean hasFrontendCommunicator()

Determine whether the frontend communicator exists in this job.

Returns:

True if the frontend communicator exists, false if it doesn't.

getClassLoader

public ClassLoader getClassLoader()

Obtain this job's backend class loader.

Returns:

Class loader.

getFileWriter

public BackendFileWriter getFileWriter()

Obtain this job's backend file writer.

Returns:

Backend file writer.

getFileReader

public BackendFileReader getFileReader()

Obtain this job's backend file reader.

Returns:

Backend file reader.

waitForCommence

public void waitForCommence()

Wait until this job commences.

getWorldChannelGroup

public ChannelGroup getWorldChannelGroup()

Obtain this job's world communicator channel group. If this job has not commenced yet, null is returned.

Returns:

Channel group.

getWorldAddress

public InetSocketAddress[] getWorldAddress()

Obtain this job's array of hosts/ports for the world communicator. The K elements are for the job backend processes in rank order. If this job has not commenced yet, null is returned.

Returns:

Array of world communicator addresses.

getFrontendChannelGroup

public ChannelGroup getFrontendChannelGroup()

Obtain this job's frontend communicator channel group. If the frontend communicator does not exist, or if this job has not commenced yet, null is returned.

Returns:

Channel group.

getFrontendAddress

public InetSocketAddress[] getFrontendAddress()

Obtain this job's array of hosts/ports for the frontend communicator. The first K elements are for the job backend processes in rank order, the K+1st element is for the job frontend process. If the frontend communicator does not exist, or if this job has not commenced yet, null is returned.

Returns:

Array of frontend communicator addresses.

getProperties

public Properties getProperties()

Obtain this job's Java system properties. If this job has not commenced yet, null is returned.

Returns:

Properties.

getMainClassName

public String getMainClassName()

Obtain this job's main class name. If this job has not commenced yet, null is returned.

Returns:

Fully qualified class name of the Java main program class to execute.

getArgs

public String[] getArgs()

Obtain this job's command line arguments. If this job has not commenced yet, null is returned.

Returns:

Array of 0 or more Java command line arguments.

setComment

public void setComment(String comment)

Set the comment string for this job backend process. The comment string appears in the detailed job status display in the Job Scheduler's web interface. Each job backend process (rank) has its own comment string. If setComment() is never called, the comment string is empty. The comment string is typically used to display this job backend process's progress. The comment string is rendered by a web browser and can contain HTML tags.

Calling setComment() causes a message to be sent to the job frontend process, which in turn causes a message to be sent to the Job Scheduler. (Any I/O errors during message sending are ignored.) Consequently, don't call setComment() too frequently, or the program's performance will suffer.

Parameters:

comment - Comment string.

getJobBackend

public static JobBackend getJobBackend()

Obtain the Job Backend object. If the Job Backend main program is running, the job backend object for the job is returned. If some other main program is running, null is returned.

Returns:

Job backend object, or null.

main

public static void main(String[] args)
                 throws Exception

Job Backend main program.

Throws:

Exception