Re: Mysterious performance degradation in exceptional cases

El día domingo, septiembre 18, 2022 a las 07:47:32a. m. -0700, Adrian Klaver escribió:

> On 9/18/22 02:30, Matthias Apitz wrote:
> > El día jueves, septiembre 15, 2022 a las 08:40:24a. m. -0700, Adrian Klaver escribió:
> >
> > > On 9/14/22 22:33, Matthias Apitz wrote:
> > > > El día miércoles, septiembre 14, 2022 a las 07:19:31a. m. -0700, Adrian Klaver escribió:
> > > >
> > > > > On 9/14/22 01:31, Matthias Apitz wrote:
> > >
>
> > > The 'app-server' does not answer, but does the database not answer also?
> > >
> > > Have you looked to see if the database is providing a response in a timely
> > > manner and if it is getting 'lost' in the 'app-server'?
> >
> > I do not "think" that the time is spent elsewhere in the 'app-server'.
> > to make a fact of the "thinking", I enabled the tracing of our dblayer
> > showing how many milliseconds have been spent between entering the dblayer and
> > returning the result to the application layers. This is in effect since
> > 36 hours now. Since September 13 the problem has not showed up anymore.
> > We are waiting for it...
>
> Is this with or without your every 10 sec 'ping' search program?

The 'ping' search was stopped on September 16, 7:45 CEST. The 'ping' search
never showed the problem.

> > > Also have you considered Tom Lane's suggestion of using auto_explain?
> >
> > I'm afraid that this would affect all other applications using the same
> > server. We still have other options to use. When the above tracing shows
> > a result, i.e. which of the high level operations of the dblayer uses
> > more time (more milliseconds) than normal, the next level is the detailed logging
> > of the ESQL/C operations (where we added time stamps which normaly this
> > logging does not have in its source code).
>
> You can load auto_explain per session as shown here:

Every connect from the ILL forks a new 'app-server' session which
creates a new ESQL/C session, and all this occur randomly when the ILL
wants to search for a book title if this is available in that library.
In short: no way.

Thanks

matthias

--
Matthias Apitz, ✉ guru(at)unixarea(dot)de, http://www.unixarea.de/ +49-176-38902045
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