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From Maciej Miklas <mac.mik...@googlemail.com>
Subject Re: Cassandra 1.x and proper JNA setup
Date Thu, 03 Nov 2011 08:16:16 GMT
According to source code, JNA is being used to call malloc and free. In
this case each cached row will be serialized into RAM.
We must be really careful when defining cache size - to large size would
cause out of memory. Previous Cassandra releases has logic that would
decrease cache size if heap is low.
Currently each row will be serialized without any memory limit checks -
assuming that I understood it right.

Those properties:
   reduce_cache_sizes_at: 0.85
   reduce_cache_capacity_to: 0.6
are not used anymore - at least not when JNA is enabled, witch is default
from Cassandra 1.0


On Wed, Nov 2, 2011 at 1:53 PM, Maciej Miklas <mac.miklas@googlemail.com>wrote:

> I've just found, that JNA will be not used from 1.1 release -
> https://issues.apache.org/jira/browse/CASSANDRA-3271
> I would be also nice to know what was the reason for this decision.
>
> Regards,
> Maciej
>
>
> On Wed, Nov 2, 2011 at 1:34 PM, Viktor Jevdokimov <
> Viktor.Jevdokimov@adform.com> wrote:
>
>> Up, also interested in answers to questions below.
>>
>>
>> Best regards/ Pagarbiai
>>
>> Viktor Jevdokimov
>> Senior Developer
>>
>> Email: Viktor.Jevdokimov@adform.com
>> Phone: +370 5 212 3063
>> Fax: +370 5 261 0453
>>
>> J. Jasinskio 16C,
>> LT-01112 Vilnius,
>> Lithuania
>>
>>
>>
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>> irrevocably delete this message and any copies.-----Original Message-----
>> From: Maciej Miklas [mailto:mac.miklas@googlemail.com]
>> Sent: Tuesday, November 01, 2011 11:15
>> To: user@cassandra.apache.org
>> Subject: Cassandra 1.x and proper JNA setup
>>
>> Hi all,
>>
>> is there any documentation about proper JNA configuration?
>>
>> I do not understand few things:
>>
>> 1) Does JNA use JVM heap settings?
>>
>> 2) Do I need to decrease max heap size while using JNA?
>>
>> 3) How do I limit RAM allocated by JNA?
>>
>> 4) Where can I see / monitor row cache size?
>>
>> 5) I've configured JNA just for test on my dev computer and so far I've
>> noticed serious performance issues (high cpu usage on heavy write load), so
>> I must be doing something wrong.... I've just copied JNA jars into
>> Cassandra/lib, without installing any native libs. This should not work at
>> all, right?
>>
>> Thanks,
>> Maciej
>>
>>
>

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