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Posted to dev@ignite.apache.org by Valentin Kulichenko <va...@gmail.com> on 2017/04/12 09:48:11 UTC
Session expiration in Cassandra store
Hi Igor,
I recently faced an issue with Cassandra store closing idle connections
after some time. While investigating I found that this is caused by
SessionPool and its SessionMonitor thread which closes sessions that were
not acquired from the pool within 5 minutes.
I have several questions regarding this:
- What is the general idea behind this?
- Why the timeout is not configurable?
- Is it possible to add an option to disable this thread completely?
Will this have any drawbacks?
-Val
Re: Session expiration in Cassandra store
Posted by Igor Rudyak <ir...@gmail.com>.
Hi Val,
Keeping session forever is not good cause it consumes resources on server
and client side as well. On the client for example you have bunch of Netty
threads.
I think if you just specify session expiration timeout to some big value (1
day for example) it should be far enough.
Igor
On Wed, Apr 12, 2017 at 12:01 PM, Valentin Kulichenko <
valentin.kulichenko@gmail.com> wrote:
> Igor,
>
> Thanks! I'm a bit in a rush with this, so already created a ticket [1] and
> assigned it to myself if you don't mind :)
>
> One more question though. Why exactly keeping sessions "forever" is bad? I
> expect store operations to happen while node is up, and currently if there
> is a pause larger than 5 minutes between consequent operations, I have to
> reopen connection which causes slowdown. I'm not sure what is the benefit
> of this and what are we trying to solve with this. Can you please clarify?
>
> [1] https://issues.apache.org/jira/browse/IGNITE-4954
>
> -Val
>
> On Wed, Apr 12, 2017 at 5:47 PM, Igor Rudyak <ir...@gmail.com> wrote:
>
>> Hi Val,
>>
>> 1) The genral idea is to have a session pool, cause closing and reopening
>> Cassandra session each time is rather expensive operation.
>>
>> 2) I can easily add session expiration timeout as a parameter for
>> Cassandra store. Will create a ticket for this.
>>
>> 3) It could be easily implemented ether, by closing and reopening session
>> every time or just keeping opened sessions forever, but both approaches are
>> bad. It's better to have a session pool and specify rather long session
>> expiration timeout.
>>
>> Igor
>>
>>
>>
>> On Apr 12, 2017 2:48 AM, "Valentin Kulichenko" <
>> valentin.kulichenko@gmail.com> wrote:
>>
>> Hi Igor,
>>
>> I recently faced an issue with Cassandra store closing idle connections
>> after some time. While investigating I found that this is caused by
>> SessionPool and its SessionMonitor thread which closes sessions that were
>> not acquired from the pool within 5 minutes.
>>
>> I have several questions regarding this:
>>
>> - What is the general idea behind this?
>> - Why the timeout is not configurable?
>> - Is it possible to add an option to disable this thread completely?
>> Will this have any drawbacks?
>>
>> -Val
>>
>>
>>
>
Re: Session expiration in Cassandra store
Posted by Valentin Kulichenko <va...@gmail.com>.
Igor,
Thanks! I'm a bit in a rush with this, so already created a ticket [1] and
assigned it to myself if you don't mind :)
One more question though. Why exactly keeping sessions "forever" is bad? I
expect store operations to happen while node is up, and currently if there
is a pause larger than 5 minutes between consequent operations, I have to
reopen connection which causes slowdown. I'm not sure what is the benefit
of this and what are we trying to solve with this. Can you please clarify?
[1] https://issues.apache.org/jira/browse/IGNITE-4954
-Val
On Wed, Apr 12, 2017 at 5:47 PM, Igor Rudyak <ir...@gmail.com> wrote:
> Hi Val,
>
> 1) The genral idea is to have a session pool, cause closing and reopening
> Cassandra session each time is rather expensive operation.
>
> 2) I can easily add session expiration timeout as a parameter for
> Cassandra store. Will create a ticket for this.
>
> 3) It could be easily implemented ether, by closing and reopening session
> every time or just keeping opened sessions forever, but both approaches are
> bad. It's better to have a session pool and specify rather long session
> expiration timeout.
>
> Igor
>
>
>
> On Apr 12, 2017 2:48 AM, "Valentin Kulichenko" <
> valentin.kulichenko@gmail.com> wrote:
>
> Hi Igor,
>
> I recently faced an issue with Cassandra store closing idle connections
> after some time. While investigating I found that this is caused by
> SessionPool and its SessionMonitor thread which closes sessions that were
> not acquired from the pool within 5 minutes.
>
> I have several questions regarding this:
>
> - What is the general idea behind this?
> - Why the timeout is not configurable?
> - Is it possible to add an option to disable this thread completely?
> Will this have any drawbacks?
>
> -Val
>
>
>
Re: Session expiration in Cassandra store
Posted by Igor Rudyak <ir...@gmail.com>.
Hi Val,
1) The genral idea is to have a session pool, cause closing and reopening
Cassandra session each time is rather expensive operation.
2) I can easily add session expiration timeout as a parameter for Cassandra
store. Will create a ticket for this.
3) It could be easily implemented ether, by closing and reopening session
every time or just keeping opened sessions forever, but both approaches are
bad. It's better to have a session pool and specify rather long session
expiration timeout.
Igor
On Apr 12, 2017 2:48 AM, "Valentin Kulichenko" <
valentin.kulichenko@gmail.com> wrote:
Hi Igor,
I recently faced an issue with Cassandra store closing idle connections
after some time. While investigating I found that this is caused by
SessionPool and its SessionMonitor thread which closes sessions that were
not acquired from the pool within 5 minutes.
I have several questions regarding this:
- What is the general idea behind this?
- Why the timeout is not configurable?
- Is it possible to add an option to disable this thread completely?
Will this have any drawbacks?
-Val