Continuum Analytics: Documentation

# How to Run with the YARN resource manager

## Overview

This script runs on the Spark cluster with the YARN resource manager and returns the hostname of each node in the cluster.

## Who is this for?

This how-to is for users of a Spark cluster who wish to run Python code using the YARN resource mananger.

## Spark YARN Summary

1. Before you start
2. Running the Job
3. Troubleshooting
4. Further information

## Before you start

To execute this example, download the `cluster-spark-yarn.py example script` to your cluster.

For this example, you’ll need Spark running with the YARN resource manager. You can install Spark and YARN using an enterprise Hadoop distribution such as Cloudera CDH or Hortonworks HDP.

## Running the Job

Here is the complete script to run the Spark + YARN example in PySpark:

    # cluster-spark-yarn.py
    from pyspark import SparkConf
    from pyspark import SparkContext

    conf = SparkConf()
    conf.setMaster('yarn-client')
    conf.setAppName('spark-yarn')
    sc = SparkContext(conf=conf)

    def mod(x):
        import numpy as np
        return (x, np.mod(x, 2))

    rdd = sc.parallelize(range(1000)).map(mod).take(10)
    print rdd

Note: you may have to install NumPy with `acluster conda install numpy`.

Run the script on the Spark cluster with spark-submit. The output shows the first ten values that were returned from the `cluster-spark-basic.py` script.

    16/05/05 22:26:53 INFO spark.SparkContext: Running Spark version 1.6.0

    [...]

    16/05/05 22:27:03 INFO scheduler.TaskSetManager: Starting task 0.0 in stage 0.0 (TID 0, localhost, partition 0,PROCESS_LOCAL, 3242 bytes)
    16/05/05 22:27:04 INFO storage.BlockManagerInfo: Added broadcast_0_piece0 in memory on localhost:46587 (size: 2.6 KB, free: 530.3 MB)
    16/05/05 22:27:04 INFO scheduler.TaskSetManager: Finished task 0.0 in stage 0.0 (TID 0) in 652 ms on localhost (1/1)
    16/05/05 22:27:04 INFO cluster.YarnScheduler: Removed TaskSet 0.0, whose tasks have all completed, from pool
    16/05/05 22:27:04 INFO scheduler.DAGScheduler: ResultStage 0 (runJob at PythonRDD.scala:393) finished in 4.558 s
    16/05/05 22:27:04 INFO scheduler.DAGScheduler: Job 0 finished: runJob at PythonRDD.scala:393, took 4.951328 s
    [(0, 0), (1, 1), (2, 0), (3, 1), (4, 0), (5, 1), (6, 0), (7, 1), (8, 0), (9, 1)]

## Troubleshooting

If something goes wrong consult the FAQ / Known issues page.

## Further information

See the Spark and PySpark documentation pages for more information.