Using Spark 2 from Python

Cloudera Data Science Workbench supports using Spark 2 from Python via PySpark. This topic describes how to set up and test a PySpark project.

PySpark Environment Variables

The default Cloudera Machine Learning engine currently includes Python 2.7.11 and Python 3.6.1. To use PySpark with lambda functions that run within the CDH cluster, the Spark executors must have access to a matching version of Python. For many common operating systems, the default system Python will not match the minor release of Python included in Machine Learning.

To ensure that the Python versions match, Python can either be installed on every CDH host or made available per job run using Spark’s ability to distribute dependencies. Given the size of a typical isolated Python environment, Cloudera recommends installing Python 2.7 and 3.6 on the cluster if you are using PySpark with lambda functions.

You can install Python 2.7 and 3.6 on the cluster using any method and set the corresponding PYSPARK_PYTHON environment variable in your project. Cloudera Machine Learning includes a separate environment variable for Python 3 sessions called PYSPARK3_PYTHON. Python 2 sessions continue to use the default PYSPARK_PYTHON variable. This will allow you to run Python 2 and Python 3 sessions in parallel without either variable being overridden by the other.

Creating and Running a PySpark Project

To get started quickly, use the PySpark template project to create a new project. For instructions, see Create a Project from a Built-in Template.

To run a PySpark project, navigate to the project's overview page, open the workbench console and launch a Python session. For detailed instructions, see Native Workbench Console and Editor.

Testing a PySpark Project in Spark Local Mode

Spark's local mode is often useful for testing and debugging purposes. Use the following sample code snippet to start a PySpark session in local mode.

from pyspark.sql import SparkSession

spark = SparkSession\
    .builder \
    .appName("LocalSparkSession") \
    .master("local") \
    .getOrCreate()

For more details, refer the Spark documentation: Running Spark Application.