[pgpool-general: 7154] Re: Long wait time when stopping Pgpool

[Nikhil Shetty]

Hi,

First of all, you are asking questions about propriety
packages. Please ask questions regarding propriety products to the
vendor
 - Sorry for that, issue is same for community pgpool

As other people already pointed out, there's an option to stop pgpool
without waiting for clients disconnected to pgpool. Probably you can
set the option to tweak systemectl related files. The way to do it
depends how the package is created, which we don't know. If you are
not sure, ask the vendor.
 - I tried this option to stop and start pgpool but this affects load
balancing. We I use systemctl to stop and start pgpool, then write
statements are sent to primary only but when I use stopping and starting
with "pgpool stop -mf" and "pgpool -f pgpool.conf -D" respectively, pgpool
doesn't recognize write and sends to standby, this is resolved only after
restarting the application

Because systemd kill -9 pgpool to not give a chance to remove the socket
files.
- This should not be the case right, because in production there will be
connections all the time and after using systemctl these files should be
removed

Thanks and Regards,
Nikhil


On Fri, Jul 17, 2020 at 3:49 AM Tatsuo Ishii <ishii at sraoss.co.jp> wrote:

> First of all, you are asking questions about propriety
> packages. Please ask questions regarding propriety products to the
> vendor.
>
> > Hi Team,
> >
> > I am testing pgpool for my workload.We have three nodes of pgpool used
> as a
> > load balancer and connection pooler across three nodes of database
> servers.
> >
> > All application connections to the database are through the pgpool.
> Without
> > stopping the application, if we want to stop the pgpool using "systemctl
> > stop edb-pgpool-4.0" then it takes a long time because connections are
> > still coming to the pgpool. Pgpool is stopped only after no new
> connections
> > appear + existing connections are terminated.
> >
> > Even after Pgpool is stopped, I can see that files(.s.PGSQL.9898 and
> > .s.PGSQL.9999) under socket_dir which in our case is /tmp are not
> removed.
> > This does not allow the pgpool to start using  "systemctl start
> > edb-pgpool-4.0". We have to manually remove the files under /tmp and then
> > start pgpool.
> >
> > I have two questions:
> > 1. Before stopping pgpool, how can we prevent new connections from coming
> > into pgpool without stopping the application and terminate the
> > existing connections so that the stop command does not wait.
>
> As other people already pointed out, there's an option to stop pgpool
> without waiting for clients disconnected to pgpool. Probably you can
> set the option to tweak systemectl related files. The way to do it
> depends how the package is created, which we don't know. If you are
> not sure, ask the vendor.
>
> > 2. After stopping pgpool, why are files under /tmp not removed?
>
> Because systemd kill -9 pgpool to not give a chance to remove the
> socket files.
>
> > PS:Files are removed from /tmp if there are no connections via
> pgpool(this
> > will never be the case in production environment)
>
> Because if there's no connection from clients, pgpool can remove the
> socket files before systemd kills pgpool.
>
> Best regards,
> --
> Tatsuo Ishii
> SRA OSS, Inc. Japan
> English: http://www.sraoss.co.jp/index_en.php
> Japanese:http://www.sraoss.co.jp
>
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