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From Kristian Waagan <kristian.waa...@oracle.com>
Subject Re: Quetion on out memory usage
Date Wed, 15 Feb 2012 18:27:56 GMT
On 15.02.2012 18:09, Katherine Marsden wrote:
> On 2/15/2012 8:45 AM, Bergquist, Brett wrote:
< snip>
>>
>> java.lang.OutOfMemoryError: GC overhead limit exceeded
>>
>
> I have not personally encountered the GC overhead limit, but google 
> search indicates it is related to the amount of time spent on garbage 
> collection ("too much") and can be overridden.
> http://www.petefreitag.com/item/746.cfm

I've seen this several times and for practical purposes I have always 
considered this the same as "Java heap space": for whatever reason 
you're trying to put more stuff on the heap than what can fit there.


< snip>
>>
>> The server is a Oracle M3000 and the Derby engine heap is setup to be 
>> 8Gb.
>>
> For a heap out of memory, I have seen occasional cases where  Derby's 
> estimate of whether it can sort in memory is wrong.   You'd need to 
> look at the plan and do some debugging with the actual query  if you 
> are able to reproduce to find out if that is the case here.
>

Not sure, but the code in impl/store/access/sort/MergeInserter may be 
relevant and a good starting point.

If you're debugging this, it may be useful to specify 
-XX:+HeapDumpOnOutOfMemoryError (and possibly 
|-XX:HeapDumpPath=/your/dump/path).

|
-- 
Kristian

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