Problem

My JIRA application starts performing very slowly, or hangs completely.

The following appears in the atlassian-jira.log:

Exception in thread "Thread-142" java.lang.OutOfMemoryError: GC overhead limit exceeded

Cause

This error indicates that the JVM took too long to free up memory during its GC process and can be thrown from the Serial, Parallel or Concurrent collectors. It is often accompanied by high CPU use, as the JVM will be constantly attempting to Garbage Collect, which can require intensive resources. This can lead to JIRA applications becoming unresponsive and in worse cases can result in the entire server being unresponsive (this will affect all applications on that server).

The parallel collector will throw an OutOfMemoryError (OOME) if too much time is being spent in garbage collection: if more than 98% of the total time is spent in garbage collection and less than 2% of the heap is recovered, an OutOfMemoryError will be thrown. This feature is designed to prevent applications from running for an extended period of time while making little or no progress because the heap is too small. If necessary, this feature can be disabled by adding the option -XX:-UseGCOverheadLimit to the command line.

This kind of OutOfMemoryError can be caused if user requests drown the available resources in the JVM. When this occurs, performance will degrade aggressively. This will eventually require a restart or the application may recover.

Resolution

1. Enable garbage collection logging, as in Troubleshoot Jira Server performance with GC logs.
2. Restart the application ASAP. This is a must do as the JVM is in an unexpected state after an OOME is thrown.
3. Monitor the application memory usage during peak periods, and as need be increase the memory, as in our Increasing JIRA application memory documentation.
4. Verify that the instance has enough memory (total heap) to operate.
   1. When allocating memory to a JVM, more memory does not always equate to a better experience. If there is a problem with third-party plugins or JIRA applications are running into certain behaviors that is causing it to use memory at a drastically increased rate, applying additional memory to the JVM can have detrimental effects and often addresses the symptom rather than the root cause. An increase in heap size will lead to longer GC times, which can render instances "frozen" when GC occurs, which can sometimes take up to 10 seconds (worse in certain cases).
5. Ensure all the JIRA application plugins are up to date. It's often recommended to disable them all with Safe Mode and test the stability of the JIRA application instance as it's highly possible one or more could be causing memory issues.
6. Disable the default, scheduled XML backup job and move to a native backup strategy.