Heap OOM for no apparent reason?

[Y. Srinivas Ramakrishna]

On 6/3/2011 7:52 AM, Raman Gupta wrote:
> On 06/03/2011 03:28 AM, John Coomes wrote:
>> Y. Srinivas Ramakrishna (y.s.ramakrishna at oracle.com) wrote:
>>> Sorry, sent previous email without addressing all of the issues.
>>>
>>> On 6/2/2011 6:15 PM, Raman Gupta wrote:
>>>> It would be *really* handy if there were a switch like:
>>>>
>>>> -XX:+StackTraceOnOutOfMemoryError
>>>
>>> Yes that would be handy, and probably not too difficult.
>>> But I wonder also if something like OnOutOfMemoryError or
>>> like would already get you enough info to get close to
>>> the problem ... (although may be because it's executed in
>>> a separate shell, by the time the command executes the
>>> process has likely gone well past the point when the problem
>>> occurred).
>>
>> No need to worry, the OnOutOfMemoryError commands are run while the
>> JVM is at a safepoint.  This worked for me:
>>
>>    java -XX:OnOutOfMemoryError='jstack %p' ...

Really, are you sure? I'd assumed you spawn off a separate (i.e. asynchronous)
shell process rather than waiting for it to complete while you waited
in the safepoint (i.e. synchronous). It could still be that one is
"lucky" and the shell happens to complete before the safepoint is
exited? Anyway, a good idea to check the code to see if there is
a synchronicity guarantee or one relies on plain luck to sometimes
get something useful (which itself is not bad, but good to know
when it is good fortune vs actual design :-)

-- ramki

>>
>> -John
>
> Excellent -- will try this later today.
>
> I did a quick search for places where OOME is caught and swallowed and
> found a few places within the JDK (such as direct ByteBuffer
> allocation), as well as a couple places in other libraries such as
> commons-pool and jgroups, the latter of which is used by Infinispan
> (though in some cases, but not all, those are logged before being
> swallowed). In short though, I still don't definitively know where the
> problem allocation is. So running jstack via OnOutOfMemoryError sounds
> like it is just the ticket.
>
> Cheers,
> Raman