Re: [Exist-open] threads and sessions

[Wolfgang M. <wol...@ex...>]

> When they merely 'use' the application, I don't keep sessions using
> functions from the session namespace: all state is stored explicitly in
> eXist and a ticket is passed to and from the client to retrieve that state.
> I've noticed that a JSESSION cookie is returned with each response,
> regardless whether I've created a session in the code or not.

This was a bug and has been fixed recently. Some eXist interfaces used
to always create a session.

> Will a request with a session identifier encoded in the url be processed by
> the same thread that sent the page with that identifier in the first place?
> Or is there no such relation between sessions and threads?

There is no relation. Threads are handled by the servlet engine. It
may pass the request to any idle thread.

> I would like to experiment with the various settings, but do not understand
> them quite well enough:
> * <pool max="20" min="1" sync-period="120000"
> wait-before-shutdown="120000"/> The "Configuration" documentation page says:
> "This pool restricts the number of parallel (basic) operations that can be
> executed by the database". Are such connections threads?

No. The pool contains the actual low-level database worker objects.
Every IO operation on the database needs to obtain one of those
objects first. However, a thread does not necessarily correspond to
one worker object. Most operations will acquire/release many worker
objects in a very fast sequence, allowing other threads to perform
other actions in between. A pool of 20 can thus handle a much larger
number of threads. You can increase it, though it doesn't make much
sense to choose a too large value since IO will become a limiting
factor.

> * How to set the session expiration? The jetty configuration has these
> elements:
> <Set name="MinThreads">10</Set>
> <Set name="MaxThreads">200</Set>
> <Set name="MaxIdleTimeMs">30000</Set>
> Does MaxIdleTimeMs govern the expiration of sessions in the sense of the
> functions in the session namespace?

The session timeout is a standard parameter which can be set in web.xml:

<session-config>
    <session-timeout>30</session-timeout>
  </session-config>

> And a related question: is there a way to trigger some action when a session
> expires? I noticed an old discussion in the mailing lists about that topic,
> wondered whether something has changed since.

No, nothing has been implemented yet. I never really needed that
feature. However, I would not object if someone provided a good
solution.

Wolfgang