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Message-ID: <6ca1ca9f-fdcf-436c-bf2a-800107f6004b@aklaver.com>
Date: Sun, 6 Oct 2024 08:52:46 -0700
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Subject: Re: CLOSE_WAIT pileup and Application Timeout
To: KK CHN <kkchn.in@gmail.com>
Cc: pgsql-general <pgsql-general@postgresql.org>
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From: Adrian Klaver <adrian.klaver@aklaver.com>
In-Reply-To: <CAKgGyB87tXPoxEwj6RZjzOKKFNuf_GroJD5VT0Xqcc6tOf2Taw@mail.gmail.com>
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On 10/6/24 06:26, KK CHN wrote:
> 
> 
> On Fri, Oct 4, 2024 at 9:17 PM Adrian Klaver <adrian.klaver@aklaver.com 

>     Seems the issue is in the application server. What is not clear to
>     me is
>     whether the connection timeout you refer to is from the mobile devices
>     to the application or the application to the Postgres server?
> 
> its from mobile devices to application server.  When I do a restart of 
> application server everything backs to normal.  But after a period of 
> time again it cripples.  That time when I netstat on Application VM lots 
> of  CLOSE_WAIT states as indicated.
> 
>     I'm
>     guessing the latter as I would expect the mobile devices to drop
>     connections more often then weekly. 
> 
>     Yes mobile devices may drops connections at any point of time if it
>     reaches an area where signal strength is poor( eg; Underground
>     parking or near the areas where mobile data coverage is poor.
>      >
> 
> 
> The topology is mobile devices  connect and update the location via 
> application VM then   finally in  PGSQL VM.
> 
> The application server and  Database server both separate virtual 
> machines.      Application server hangs most often not the database VM. 
> Since there are other applications which update to the database VM 
> without any issue.  The DB VM caters all the writes from other 
> applications. But those applications are different, not fleet management 
> one.

 From what I see this really has nothing to do with the Postgres 
backend. It is a matter of communication, actually lack of 
communication, between the mobile devices and the application server. A 
broad answer is that something needs to be done to gracefully deal with 
mobile device connection drops


-- 
Adrian Klaver
adrian.klaver@aklaver.com