Hadoop中createAndSubmitJob()的源代码和过程分析以及实现了什么功能？

public Job createAndSubmitJob() throws Exception    {

    Job    job = null;

    try    {

      synchronized(this)    {

           metaFolder = createMetaFolderPath();

        jobFS    = metaFolder.getFileSystem(getConf());

        job =    createJob();

}

      if    (!inputOptions.shouldUseDiff()) {

           createInputFileListing(job);

}

         job.submit();

         submitted = true;

    } finally    {

      if    (!submitted) {

           cleanup();}

    return    job;

}