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From Gurpreet Singh <gurpreet.si...@gmail.com>
Subject Re: key_cache_size_in_mb
Date Thu, 28 Jun 2012 18:25:17 GMT
anyone have an explanation for this?
This kinda screws up memory calculations.

/G

On Mon, Jun 25, 2012 at 5:50 PM, Gurpreet Singh <gurpreet.singh@gmail.com>wrote:

> Hi,
> I have a question about cassandra 1.1
>
> Just wanted to confirm if key_cache_size_in_mb is the maximum amount of
> memory that key cache will use in memory? If not, what is it?
>
> My observations:
> With key cache disabled, I started cassandra. I invoked Full GC through
> jconsole a couple of times just to make sure that memory is freed up.
> Total heap memory in use is 2.2 gigs. I have almost 550 million keys, so
> this looked reasonable as the bloom filter itself is around 1 gig.
>
> I enabled key cache again by making key_cache_size_in_mb to a value 800.
> This would lead cassandra to load a previously saved key cache file of size
> 98 mb on disk. I restarted cassandra again. This time the heap size
> increased to 4.2 gigs. I checked the cache sizing in jconsole.
>
> KeyCacheCapacityInMb: 799
> KeyCacheSize: 410,316,048
>
> This says that the key cache size is 410 mb. However the increase in the
> heap is 2 gigs. Doesnt add up!!
>
> Can anyone explain this?
> Thanks
> Gurpreet
>

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