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From Edward Capriolo <>
Subject Re: ParNew and caching
Date Sat, 10 Dec 2011 20:20:19 GMT
I am not sure if there is a ticket on this but I have always thought the
row cache should not bother caching an entry bigger then n columns.

Murmurs of a slice cache might help as well.

On Saturday, December 10, 2011, Peter Schuller <>
>> After re-reading my post, what I meant to say is that I switched from
>> Serializing cache provider to ConcurrentLinkedHash cache provider and
>> saw better performance, but still far worse than no caching at all:
>> - no caching at all : 25-30ms
>> - with Serializing provider : 1300+ms
>> - with Concurrent provider : 500ms
>> 100% cache hit rate.  ParNew is the only stat that I see out of line, so
>> seems like still a lot of copying
> In general, if you want to get to the bottom of this stuff and you
> think GC is involved, always run with -XX:+PrintGC -XX:+PrintGCDetails
> -XX:+PrintGCTimeStamps -XX:+PrintGCDateStamps so that the GC activity
> can be observed.
> 1300+ should not be GC unless you are having fallbacks to full GC:s
> (would be possible to see with gc logging) and it should definitely be
> possible to avoid full gc:s being extremely common (but eliminating
> them entirely may not be possible).
> --
> / Peter Schuller (@scode,

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