After giving JIRA a large amount of heap memory, errors like this appear in the logs:
In some cases the JVM will terminate with a HotSpot error. The Error message usually refers to being "out of swap space" even if the system has sufficient swap:
This is caused by a bug in 32-bit Sun JVMs. You can read about Sun's bug in their issue tracker.
There is a workaround implemented by Lucene which has been incorporated into JIRA 4.1. This works for most memory sizes, but large heap sizes will still encounter this problem.
Upgrade to JIRA 4.1+ to implement the Lucene workaround.