Why do spark-submit and spark-shell fail with ‘Failed to find Spark assembly JAR. You need to build Spark before running this program.'?

The error message “failed to find spark assembly JAR. You need to build spark before running this program” pops, when spark can’t locate the spark assembly jar files. Understanding the causes can help you to troubleshoot and solve the issue. Let’s explore more in this blog.

Table of Contents:

• Common Causes
• Troubleshooting techniques
• Conclusion
• FAQ’s

Common Causes of ‘Failed to find Spark assembly JAR‘

There are a few common causes due to which you might be facing this issue. It can include missing dependencies, improper classpath settings, and missing spark assembly jars.

Let us examine them:

1. Missing Spark assembly jar

This is the most common cause and it occurs when the spark assembly jars are not present in the expected location. Make sure that the spark installation directory contains all necessary jars. To verify the correct path, You can use the SPARK_HOME environment variable.

2. Incorrect classpath configuration

If the path is not set correctly, spark cannot find the required file. Ensure that the –jars option in the spark-submit command includes a path to the spark assembly file.

Example:

spark-submit --jars /path/to/spark-assembly.jar --class 'your.class' your-application.jar

3. Missing dependencies

Sometimes, additional dependencies are required for your application to run. Make sure all dependencies have classpaths and are specified in the spark_submit command using the –jars option.

4. Build issue

If you are building the spark from the source, make sure that the build process is completed successfully and that the resulting jar is in the expected location. You can rebuild the spark by running the following command:

./build/make-distribution.sh --tgz

5. Environment variable

Make sure that spark_home and path variables are correct. The spark_home variable should point to the root directory of your spark installation and the path should have a bin directory in spark.

6. Cluster configuration

If you are running spark in the cluster, ensure the cluster node has access to the spark assembly jar. You should distribute the jars to all nodes.

Troubleshooting Techniques

Troubleshooting techniques involve verifying the spark installation, checking for the spark assembly, building the spark from the source, correcting the classpath, verifying the environment variable, and checking for all the permissions.

1. Verify Spark Installation

Make sure the spark is installed correctly in your system. Check Spark Home environment variable points toward the spark installation directory.

echo $SPARK_HOME

If the Spark_Home is not set, set it to the correct path:

export SPARK_HOME=/path/to/spark

2. Check for Spark Assembly Jars

Ensure the spark assembly jar file exists in the jars directory of your spark installation. The spark file is named like spark-assembly-<version>-hadoop<version>.jar

ls $SPARK_HOME/jars | grep spark-assembly

3. Build Spark from the source

Make sure the build process is completed successfully and generate the necessary jars.

./build/mvn -DskipTests clean package

This command builds spark and creates assembly jars in the target directory.

4. Set the Classpath correctly

Make sure the classpath contains the Spark assembly jar.

spark-submit --jars $SPARK_HOME/jars/spark-assembly-<version>-hadoop<version>.jar --class 'your.class' your-application.jar

5. Check the environment variable

export PATH=$SPARK_HOME/bin:$PATH

You can use this command to verify, that Spark_home and path environment variables are set correctly.

6. Review cluster

If you are running Spark on a cluster, ensure all nodes have access to the Spark assembly jars.

7. Check permission

Make sure that you have the necessary permission to access the spark assembly jars. You can even change the permission using chmod command.

chmod +r $SPARK_HOME/jars/spark-assembly-<version>-hadoop<version>.jar

8. Consult Logs for error

Check the log files generated by Spark for any error messages or additional information. The logs can provide you with clues about the error and how to fix it.

9. Reinstall spark

If all else fails, consider reinstallation of Spark. Remove the current one and download a fresh copy from the Spark website.

rm -rf $SPARK_HOME

wget https://downloads.apache.org/spark/spark-<version>/spark-<version>-bin-hadoop<version>.tgz

tar -xvzf spark-<version>-bin-hadoop<version>.tgz -C /path/to/installation

export SPARK_HOME=/path/to/installation/spark-<version>-bin-hadoop<version>

Conclusion

To resolve the ‘failed to find Spark assembly jar’ error, make sure Spark is installed correctly and necessary assembly jars are present. Verify the environment variable, and classpath configuration, and rebuild Spark if needed. Proper troubleshooting will enable the successful execution of your Spark application.

FAQs