Question

this is how my jobrunner looks. How can I set low priority while triggering this job itself ?

public int run(String[] args) throws Exception {
    this.initJob();
    Path outputPath = new Path(args[2]);
    FileInputFormat.setInputPaths(job, args[0]);
    FileOutputFormat.setOutputPath(job, outputPath);

    job.getConfiguration().set("FREQUENCY", args[3]);
    job.getConfiguration().set("TIMEZONE", args[4]);

    boolean rc = job.waitForCompletion(true);
    if (rc) {
        return 0;
    }
    return 1;
}
public void initJob() throws IOException {
    job = new Job(getConf(), "Stats Data Cruncher");
    job.setMapOutputKeyClass(Text.class);       
    job.setMapOutputValueClass(Text.class);
    job.setOutputKeyClass(Text.class);
    job.setOutputValueClass(NullWritable.class);
    Job.setInputFormatClass(LzoTextInputFormat.class);  

    job.setJarByClass(JobRunner.class);
    job.setMapperClass(StatsMapper.class);
    job.setCombinerClass(StatsCombiner.class);        
    job.setReducerClass(StatsReducer.class);
}

is this line valid to set LOW priority ?

job.getConfiguration().set("PRIORITY", "LOW");

Answer 1

“mapred.job.priority” is the property you are looking for.

You can set this in your configuration like this:

Configuration conf = new Configuration();
// set the priority to VERY_HIGH
conf.set("mapred.job.priority", JobPriority.VERY_HIGH.toString());