Running Applications with CDS 3 Powered by Apache Spark
With CDS 3 Powered by Apache Spark, 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:
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
that refers to the SparkContext, calls the
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
$ 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
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.