(Preliminary) RFC 7038914: VM could throw uncaught OOME in ReferenceHandler thread (original) (raw)

Alan Bateman Alan.Bateman at oracle.com
Tue Apr 30 15:44:42 UTC 2013

On 30/04/2013 15:57, Thomas Schatzl wrote:

Hi all,

the webrev at http://cr.openjdk.java.net/~tschatzl/7038914/webrev/ presents a first stab at the CR "7038914: VM could throw uncaught OOME in ReferenceHandler thread". The problem is that under very heavy memory pressure, there is the reference handler throws an exception with the message "Exception: java.lang.OutOfMemoryError thrown from the UncaughtExceptionHandler in thread "Reference Handler". The change improves handling of out-of-memory conditions in the ReferenceHandler thread. Instead of crashing the thread, and then disabling reference processing, it catches this exception and continues. It's surprising to heard that the Reference Handler thread failed with OOME. I wouldn't expect anything in this code path to throw OOME, except maybe in fast-path for sun.misc.Cleaner but that will abort the VM be it fails. The enqueue method that you override in the test to provoke this is package-private so it's unlikely that the test or whatever that resulted in this bug report is doing that.

So I'm again this proposed change, rather I'm just trying to understand how it happened. Is there instrumentation involved by any chance? It the OOME something other than "java heap" or do we know?

-Alan.

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