How to Fix Out of Memory Errors in Jenkins

To fix OutOfMemoryError in Jenkins, increase the Java Virtual Machine (JVM) heap size by adjusting the JAVA_OPTS or JENKINS_JAVA_OPTIONS environment variables. This allocates more memory to Jenkins and prevents it from running out of memory during builds or operations.

Why This Happens

Jenkins runs on Java and uses memory allocated by the Java Virtual Machine (JVM). If Jenkins tries to use more memory than the JVM allows, it crashes with an OutOfMemoryError. This usually happens when builds or plugins require more memory than the default JVM settings provide.

bash

java -jar jenkins.war

Output

Exception in thread "main" java.lang.OutOfMemoryError: Java heap space

The Fix

Increase the JVM heap size by setting environment variables before starting Jenkins. For example, set JAVA_OPTS or JENKINS_JAVA_OPTIONS to allocate more memory. This gives Jenkins more space to work and stops the out of memory error.

bash

export JAVA_OPTS="-Xms512m -Xmx2048m"
java -jar jenkins.war

Output

Jenkins started successfully with increased heap size

Prevention

To avoid running out of memory in the future, monitor Jenkins memory usage regularly and adjust JVM settings as needed. Keep plugins updated and remove unused ones to reduce memory load. Also, consider using Jenkins agents to distribute workload and reduce memory pressure on the main server.

Related Errors

Other memory-related errors include GC overhead limit exceeded and PermGen space errors. These can also be fixed by tuning JVM options like -XX:MaxPermSize or upgrading to newer Java versions that replace PermGen with Metaspace.

Key Takeaways

Increase Jenkins JVM heap size using JAVA_OPTS or JENKINS_JAVA_OPTIONS to fix out of memory errors.

Monitor memory usage and optimize plugins to prevent memory issues.

Distribute workload with Jenkins agents to reduce memory pressure on the main server.

Update Java and Jenkins regularly to benefit from memory management improvements.