PySpark

Overview

You can use this Snap to execute a PySpark script. It formats and executes a 'spark-submit' command in a command line interface, and then monitors the execution status.



Prerequisites

The Snap must be executed in a Groundplex on a Spark cluster node or an edge node.

Snap views

View Description Examples of upstream and downstream Snaps
Input If the upstream Snap is connected, this Snap executes after each input document and produces a document in the output view or an error document in the error view. Each input document is used to evaluate expression properties in the Snap.
Output

If the script executes successfully with an exit code 0, the Snap produces output documents with the status. If the script is coded to produce a standard output, it is also included in the output document. It produces one output document for each execution of the PySpark script.

If the script fails (with an exit code other than 0), the Snap produces an error document in the error view.
Error

Error handling is a generic way to handle errors without losing data or failing the Snap execution. You can handle the errors that the Snap might encounter when running the pipeline by choosing one of the following options from the When errors occur list under the Views tab. The available options are:

  • Stop Pipeline Execution Stops the current pipeline execution when an error occurs.
  • Discard Error Data and Continue Ignores the error, discards that record, and continues with the remaining records.
  • Route Error Data to Error View Routes the error data to an error view without stopping the Snap execution.

Learn more about Error handling in Pipelines.

Snap settings

Legend:
  • Expression icon (): Allows using pipeline parameters to set field values dynamically (if enabled). SnapLogic Expressions are not supported. If disabled, you can provide a static value.
  • SnapGPT (): Generates SnapLogic Expressions based on natural language using SnapGPT. Learn more.
  • Suggestion icon (): Populates a list of values dynamically based on your Snap configuration. You can select only one attribute at a time using the icon. Type into the field if it supports a comma-separated list of values.
  • Upload : Uploads files. Learn more.
Learn more about the icons in the Snap settings dialog.
Field / Field set Type Description
Label String

Required. Specify a unique name for the Snap. Modify this to be more appropriate, especially if more than one of the same Snaps is in the pipeline.

Default value: PySpark

Example: PySpark
Spark home String/Expression Specify the Spark home directory where spark-submit command is located under the bin/ subdirectory. If this property is empty, the Snap tries to find a value for "SPARK_HOME" or "CDH_SPARK_HOME" in the environment variables or system properties.

Default value: None.

Example: /opt/cloudera/parcels/CDH-5.8.4-1.cdh5.8.4.p0.5/lib/spark
Spark Submit Command Dropdown list

Specify the Spark home directory where spark-submit command is located under the bin/ subdirectory. If this property is empty, the Snap tries to find a value for "SPARK_HOME" or "CDH_SPARK_HOME" in the environment variables or system properties.

Choose the Spark command to run your PySpark application on a cluster. The available options are:
  • spark-submit: This is the generic command-line tool to submit applications to Apache Spark.
  • spark2-submit: Specifically refers to the Apache Spark 2.x binary. Use this option when your pipeline relies on APIs or behaviors specific to Spark 2.
  • spark3-submit: Specifically refers to Apache Spark 3.x. Use this option when you want to take advantage of the new features introduced in Spark 3, such as adaptive query execution, new SQL functions, and improved ANSI compliance.
Note: Ensure the program is accessible from the Spark Home under the bin folder. Learn more about the Spark submit command.

Default value: spark-submit

Example: spark2-submit
Spark submit args String/Expression Specify the arguments for the spark-submit command, if any.

Default value: None.

Example:

$sparkSubmitArgs

_sparkSubmitArgs

--master yarn --deploy-mode cluster (to submit the PySpark script to YARN)

--principal snaplogic/[email protected] --keytab /snaplogic.keytab.new (to submit the PySpark script to Kerberos-enabled cluster)
Edit PySpark script Button This property enables you to edit a PySpark script. A 'word-count' sample script is included with the Snap. Click to open an editor and save. To try the sample script, enter a file path to an input text file in the Script args property. In the script editor, a script can be exported, imported, or a template can be generated as required. Learn more: RDD Programming Guide - Spark 4.0.0 Documentation
Script args String/Expression Specify the arguments for the PySpark script.

Default value: None.

Example: hdfs:///tmp/sample.txt hdfs:///tmp/output.dir/ (input file and output directory for 'wordcount' sample script)
YARN RM (host:port) String/Expression Specify the hostname and port number of the Yarn Resource Manager in the 'host:port' format. This property is required to stop a PySpark job in progress.
Note: If YARN is not used to submit the PySpark script, then stopping the Snap will not halt the job submitted to Spark.

Default value: None.

Example: rm01.hadoop.cluster:8032
Timeout (sec) Integer/Expression Specify the timeout limit in seconds. If negative or empty, the Snap will not time out until spark-submit returns the result.

Default value: -1

Example: 600 (10 minutes)
Snap execution Dropdown list
Choose one of the three modes in which the Snap executes. Available options are:
  • Validate & Execute: Performs limited execution of the Snap and generates a data preview during pipeline validation. Subsequently, performs full execution of the Snap (unlimited records) during pipeline runtime.
  • Execute only: Performs full execution of the Snap during pipeline execution without generating preview data.
  • Disabled: Disables the Snap and all Snaps that are downstream from it.

Default value: Execute only

Example: Validate & Execute

Troubleshooting

The Snap produces an error document if a given PySpark script fails to execute. It may be helpful in troubleshooting to execute the script in a command line interface of a Groundplex where the Snap is executed.

Examples