AW: Unexplanable events in GC logs

[Bernd Eckenfels]

Am 23.01.2014, 09:38 Uhr, schrieb Denny Kettwig <denny.kettwig at werum.de>:
> The first event is a very frequent CMS collections on the first node for  
> about 11 hours. We are talking here about a peak value of 258 CMS  
> collections per hour. From my knowledge this event starts without any  
> reason and ends without any reason since the old space is below 10%  
> usage in this time frame. I do not know what might have caused this CMS  
> collection. We already experienced similar events on this cluster in the  
> past, but at a much higher heap usage (above 90%) and under high load  
> with most likely a huge heap fragmentation and the frequent CMS  
> collections ended with a single very long Full GC that defragmented the  
> heap. In the current event all this is not the case. I attached the  
> relevant part of the GC log.

I had discussed similiar problems hare in the past as well. I havent  
really found the reason, but some things consiedered have been filling up  
of the codecache and a hossed estimator (using OccupancyOnly might help  
here).

Greetings
Bernd