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List:       tomcat-user
Subject:    Re: Clarification on behaviour after pool exhaustion happen in tomcat jdbc pool 9.0.16
From:       Sampath Rajapakshe <sampath () wso2 ! com ! INVALID>
Date:       2021-08-09 5:57:47
Message-ID: CAGGb7xZnQnpKPTteGLgT8d3zj=HJXvxfqEMTo3NmPT0wuJr1cg () mail ! gmail ! com
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Hi Chris,

Thanks for the clarification. I've gone through the blog, In our case, we
know the reason for the pool exhausted behaviour, there are slow queries
and also due to high TPS where pool is not enough. So we are expected to
get pool exhaustion with current configurations. What we wanted to verify
was the behaviour after pool exhaustion. Do the current executing
connections continue their executions during pool exhausted duration? As
per our observations, they do not, and connections are stuck without
executing any queries until maxWait. is that the expected behaviour after
pool exhaustion?

Thanks and Regards,
Sampath

On Sat, Aug 7, 2021 at 3:43 AM Christopher Schultz <
chris@christopherschultz.net> wrote:

> Sampath,
>
> On 8/6/21 08:37, Sampath Rajapakshe wrote:
> > Hi All,
> >
> > In my local setup before pool exhaustion exception is thrown, all the
> > connections seem to be in freezed and when checking processList in mysql,
> > those connections are in sleep state and doesn't execute any queries.
> After
> > waiting for maxWait period the pool exhausted exception gets thrown and
> > seems to reset the connections and then the queries are getting processed
> > as normally.
>  >
> > So, my question is, with pool exhausted scenarios, doesn't existing
> > connections execute their queries during that time(maxWait) and try to
> > resolve the exhausted behaviour by releasing those connections to idle
> > queue automatically? When checking the JMX matrix during this pool
> > exhausted time all the connections are in the active queue.
>
>
> https://blog.christopherschultz.net/2009/03/16/properly-handling-pooled-jdbc-connections/
>
> > If not, what i am experiencing is as expected behaviour where the system
> is
> > stuck after pool exhaustion for the best case of maxWait?
>
> Most of the time I've seen this kind of behavior it's due to sloppy
> resource-management.
>
> -chris
>
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-- 

*Sampath Rajapakse* | Senior Software Engineer | WSO2 Inc.

+94717313761 | sampath@wso2.com


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