Re: CLOSE_WAIT pileup and Application Timeout

On Mon, Oct 7, 2024 at 12:07 AM Alvaro Herrera <alvherre(at)alvh(dot)no-ip(dot)org>
wrote:

> On 2024-Oct-04, KK CHN wrote:
>
> > The mobile tablets are installed with the android based vehicle
> > tracking app which updated every 30 seconds its location fitted inside
> the
> > vehicle ( lat long coordinates) to the PostgreSQL DB through the java
> > backend application to know the latest location of the vehicle and its
> > movement which will be rendered in a map based front end.
> >
> > The vehicles on the field communicate via 443 to 8080 of the Wildfly
> > (version 27 ) deployed with the vehicle tracking application developed
> with
> > Java(version 17).
>
> It sounds like setting TCP keepalives in the connections between the
> Wildfly and the vehicles might help get the number of dead connections
> down to a reasonable level. Then it's up to Wildfly to close the
> connections to Postgres in a timely fashion. (It's not clear from your
> description how do vehicle connections to Wildfly relate to Postgres
> connections.)
>
>
Where do I have to introduce the TCP keepalives ? in the OS level or
application code level ?

[root(at)dbch wildfly-27.0.0.Final]# cat /proc/sys/net/ipv4/tcp_keepalive_time
7200
[root(at)dbch wildfly-27.0.0.Final]# cat /proc/sys/net/ipv4/tcp_keepalive_intvl
75
[root(at)dbch wildfly-27.0.0.Final]# cat
/proc/sys/net/ipv4/tcp_keepalive_probes
9
[root(at)dbch wildfly-27.0.0.Final]#

These are the default values in the OS level. Do I need to reduce all the
above three values to say 600, 20, 5 ? Or need to be handled in the
application backend code ?

Any hints much appreciated..

>
> I wonder if the connections from Wildfly to Postgres use SSL? Because
> there are reported cases where TCP connections are kept and accumulate,
> causing problems -- but apparently SSL is a necessary piece for that to
> happen.
>
No SSL in between Wildfly (8080 ) to PGSQL(5432). Both the machines
internal lan VMs in the same network. Only the devices on the field
(fitted on the vehicles) communicate to the application backend via a
public URL :443 port then it connectes to the 8080 of wildfly then the
java code connects the database server running on 5432 on the internal LAN
network.

>

> --
> Álvaro Herrera 48°01'N 7°57'E —
> https://www.EnterpriseDB.com/
> Thou shalt study thy libraries and strive not to reinvent them without
> cause, that thy code may be short and readable and thy days pleasant
> and productive. (7th Commandment for C Programmers)
>