Package 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

Version:
24-Jan-2012
Author:
Alan Kaminsky

  • Method Details

    • 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.

      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.
      IOException - if any.

    • 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.
      IOException - if any.

    • jobFinished

      public void jobFinished(JobFrontendRef theJobFrontend) throws IOException
      Report that the job finished.

      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.
      IOException - if any.

    • renewLease

      public void renewLease(JobFrontendRef theJobFrontend) throws IOException
      Renew the lease on the job.

      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.
      IOException - if any.

    • 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.
      IOException - if any.

    • reportResource

      public void reportResource(JobFrontendRef theJobFrontend, String resourceName, ByteSequence content) throws IOException
      Report the content for a previously-requested resource.

      Report the content for a previously-requested resource.

      Specified by:
      reportResource in interface JobBackendRef
      Parameters:
      theJobFrontend - a JobFrontendRef object
      resourceName - a String object
      content - a ByteSequence object
      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.

      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.
      IOException - if any.

    • outputFileWriteResult

      public void outputFileWriteResult(JobFrontendRef theJobFrontend, int ffd, IOException exc) throws IOException
      Report the result of writing the given output file.

      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.
      IOException - if any.

    • outputFileFlushResult

      public void outputFileFlushResult(JobFrontendRef theJobFrontend, int ffd, IOException exc) throws IOException
      Report the result of flushing the given output file.

      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.
      IOException - if any.

    • outputFileCloseResult

      public void outputFileCloseResult(JobFrontendRef theJobFrontend, int ffd, IOException exc) throws IOException
      Report the result of closing the given output file.

      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.
      IOException - if any.

    • inputFileOpenResult

      public void inputFileOpenResult(JobFrontendRef theJobFrontend, int bfd, int ffd, IOException exc) throws IOException
      Report the result of opening the given input file.

      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.
      IOException - if any.

    • 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.

      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.
      IOException - if any.

    • inputFileSkipResult

      public void inputFileSkipResult(JobFrontendRef theJobFrontend, int ffd, long len, IOException exc) throws IOException
      Report the result of skipping the given input file.

      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.
      IOException - if any.

    • inputFileCloseResult

      public void inputFileCloseResult(JobFrontendRef theJobFrontend, int ffd, IOException exc) throws IOException
      Report the result of closing the given input file.

      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.
      IOException - if any.

    • 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.
      Parameters:
      args - an array of String objects.
      Throws:
      Exception - if any.