Java - shutting down on Out of Memory Error

Question

I've heard very contradictory things on how to best handle this, and am stuck with the following dilemma:

• an OOME brings down a thread, but not the whole application
• and I need to bring down the whole application but can't because the thread doesn't have any memory left

I've always understood best practice is let them go so the JVM can die because the JVM is in an inconsistent state at that point, but that doesn't seem to be working here.

Answer 1

OutOfMemoryError is just like any other error. If it escapes from Thread.run() it will cause thread to die. Nothing more. Also, when a thread dies, it is no longer a GC root, thus all references kept only by this thread are eligible for garbage collection. This means JVM is very likely to recover from OOME.

If you want to kill your JVM no matter what because you suspect it can be in an inconsistent state, add this to your java options:

-XX:OnOutOfMemoryError="kill -9 %p"

%p is the current Java process PID placeholder. The rest is self-explained.

Of course you can also try catching OutOfMemoryError and handling it somehow. But that's tricky.