[Koha-devel] Sessions terminated at random under Plack

[Magnus Enger]

Dear Community,

I am seeing a strange problem, and I'm not sure where to start digging.

I have a (big) server with 30 odd Koha instances. One of these
instances has been running under Plack for quite some time now,
without any problems.

Two new instances have a problem where librarians get kicked out of
the intranet more or less frequently, with a message like "Your
session has expired, please log in again".

We had this problem on 3.22.x.
After upgrading to 16.05.02 it went away.
After upgrading to 16.05.03 last night it came back again.

It is not consistent. Earlier today it looked like you could log in,
click on a link, get thrown out, login again and then things would
work. Later users got kicked out every single time they clicked on a
link in the intranet.

All sites are running off the official Debian packages, on the same server.
Memcached is installed, enabled and used for storing sessions.
Switching SessionStorage to the DB does not stop the problem.
Stopping and disabling Plack for these two instances makes the problem go away.

I have not found anything interesting in Plack or Apache logs.

Anyone got a hunch what might be causing this? Or where to start digging?

Best regards,
Magnus