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From Vijay <vijay2...@gmail.com>
Subject Re: key_cache_size_in_mb
Date Thu, 28 Jun 2012 19:22:37 GMT
in 1.1 we dont calculate the Key size accurately, hence we have the fix in
https://issues.apache.org/jira/browse/CASSANDRA-4315

Regards,
</VJ>



On Thu, Jun 28, 2012 at 11:25 AM, Gurpreet Singh
<gurpreet.singh@gmail.com>wrote:

> 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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