Running Applications with CDS 3.2.1 Powered by Apache Spark

With CDS 3.2.1 Powered by Apache Spark (CDS 3.2.1), you can run Apache Spark 3 applications locally or distributed across a cluster, either by using an interactive shell or by submitting an application. Running Spark applications interactively is commonly performed during the data-exploration phase and for ad hoc analysis.

The Spark 3 job commands

With Spark 3, you use slightly different command names than with Spark 2, so that you can run both versions of Spark side-by-side without conflicts:

  • spark3-submit instead of spark-submit.

  • spark3-shell instead of spark-shell.

  • pyspark3 instead of pyspark.

For development and test purposes, you can also configure each host so that invoking the Spark 2 command name runs the corresponding Spark 3 executable.

Canary test for pyspark3 command

The following example shows a simple pyspark3 session that refers to the SparkContext, calls the collect() function which runs a Spark 3 job, and writes data to HDFS. This sequence of operations helps to check if there are obvious configuration issues that prevent Spark 3 jobs from working at all. For the HDFS path for the output directory, substitute a path that exists on your own system.

$ hdfs dfs -mkdir /user/jdoe/spark
$ pyspark3
...
SparkSession available as 'spark'.
>>> strings = ["one","two","three"]
>>> s2 = sc.parallelize(strings)
>>> s3 = s2.map(lambda word: word.upper())
>>> s3.collect()
['ONE', 'TWO', 'THREE']
>>> s3.saveAsTextFile('hdfs:///user/jdoe/spark/canary_test')
>>> quit()
$ hdfs dfs -ls /user/jdoe/spark
Found 1 items
drwxr-xr-x   - jdoe spark-users  0 2016-08-26 14:41 /user/jdoe/spark/canary_test
$ hdfs dfs -ls /user/jdoe/spark/canary_test
Found 3 items
-rw-r--r--   3 jdoe spark-users  0 2016-08-26 14:41 /user/jdoe/spark/canary_test/_SUCCESS
-rw-r--r--   3 jdoe spark-users  4 2016-08-26 14:41 /user/jdoe/spark/canary_test/part-00000
-rw-r--r--   3 jdoe spark-users 10 2016-08-26 14:41 /user/jdoe/spark/canary_test/part-00001
$ hdfs dfs -cat /user/jdoe/spark/canary_test/part-00000
ONE
$ hdfs dfs -cat /user/jdoe/spark/canary_test/part-00001
TWO
THREE

Fetching Spark 3 Maven Dependencies

The Maven coordinates are a combination of groupId, artifactId and version. The groupId and artifactId are the same as for the upstream Apache Spark project. For example, for spark-core, groupId is org.apache.spark, and artifactId is spark-core_2.12, both the same as the upstream project. The version is different for the Cloudera packaging: see Using the CDS 3 Powered by Apache Spark Maven Repository for the exact name depending on which release you are using.

Accessing the Spark 3 History Server

The Spark 3 history server is available on port 18089, rather than port 18088 as with the Spark 2 history server.