How to deal with “java.lang.OutOfMemoryError: Java heap space” error?

Question

I am writing a client-side Swing application (graphical font designer) on Java 5. Recently, I am running into java.lang.OutOfMemoryEr

Answer 1

If you need to monitor your memory usage at runtime, the java.lang.management package offers MBeans that can be used to monitor the memory pools in your VM (eg, eden space, tenured generation etc), and also garbage collection behaviour.

The free heap space reported by these MBeans will vary greatly depending on GC behaviour, particularly if your application generates a lot of objects which are later GC-ed. One possible approach is to monitor the free heap space after each full-GC, which you may be able to use to make a decision on freeing up memory by persisting objects.

Ultimately, your best bet is to limit your memory retention as far as possible whilst performance remains acceptable. As a previous comment noted, memory is always limited, but your app should have a strategy for dealing with memory exhaustion.