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From Gurpreet Singh <gurpreet.si...@gmail.com>
Subject Re: key_cache_size_in_mb
Date Thu, 28 Jun 2012 22:40:23 GMT
Vijay,
I am running into an issue right now, not sure if its related to this one.

My cassandra 1.1 was running fine for a week, and the key cache size (as
checked by jconsole) increased to almost 650 mb. It has 13.7million keys. I
have set key_cache_size_in_mb to 800 mb. I checked the heap size, and it
was at 6 gigs. All good!
However, when i try to restart cassandra, it is unable to start now. Before
i shut it down, it seemed fine at 6 gigs, which means its able to handle
the memory requirements just fine. However it is not able to start up
anymore with the same key cache. jconsole says that the heap is full.

Thanks
/G

On Thu, Jun 28, 2012 at 12:22 PM, Vijay <vijay2win@gmail.com> wrote:

> 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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