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From: Jonathan Ellis <jbellis@gmail.com>
Date: Thu, 3 Nov 2011 12:55:36 -0500
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Subject: Re: Cassandra 1.x and proper JNA setup
To: user@cassandra.apache.org, m.miklas@gmx.net
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Relying on that was always a terrible idea because you could easily
OOM before it could help.  There's no substitute for "don't make the
caches too large" in the first place.

We're working on https://issues.apache.org/jira/browse/CASSANDRA-3143
to make cache sizing easier.

On Thu, Nov 3, 2011 at 3:16 AM, Maciej Miklas <mac.miklas@googlemail.com> w=
rote:
> According to source code, JNA is being used to call malloc and free. In t=
his
> 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:
> =A0=A0 reduce_cache_sizes_at: 0.85
> =A0=A0 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
>>>
>>>
>>>
>>> Disclaimer: The information contained in this message and attachments i=
s
>>> intended solely for the attention and use of the named addressee and ma=
y be
>>> confidential. If you are not the intended recipient, you are reminded t=
hat
>>> the information remains the property of the sender. You must not use,
>>> disclose, distribute, copy, print or rely on this e-mail. If you have
>>> received this message in error, please contact the sender immediately a=
nd
>>> 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
>>>
>>
>
>


--=20
Jonathan Ellis
Project Chair, Apache Cassandra
co-founder of DataStax, the source for professional Cassandra support
http://www.datastax.com