[ome-users] sessionid files in /tmp

Wed Jun 25 15:08:18 BST 2014

Dear John

As users create new sessions on the OMERO.web, session data can accumulate in your session store. Because OMERO.web uses the file based backend, your temporary directory will contain an increasing number of files. Django does not provide automatic purging of expired sessions. Therefore, it’s your job to purge expired sessions on a regular basis. Django provides a clean-up management command for this purpose: clear sessions. It’s recommended to call this command on a regular basis, for example as a daily cron job.

cd OMERO/lib/python/omeroweb
python manage.py clearsessions

Note that the cache backend isn’t vulnerable to this problem, because caches automatically delete stale data.
If you wish to change it to cache based, first install Memcached  and a memcached binding. There are several python memcached bindings available; the two most common are python-memcached and pylibmc. Then set the following

$ bin/omero web stop
$ bin/omero config set omero.web.caches '{"default": { "BACKEND": "django.core.cache.backends.memcached.MemcachedCache", "LOCATION": "127.0.0.1:11211", "TIMEOUT": "86400" } }'
$ bin/omero config set omero.web.session_engine "django.contrib.sessions.backends.cache"
$ bin/omero web start

I hope it will help

Kind regards
Ola

From: "John Webber (NBI)" <John.Webber at nbi.ac.uk<mailto:John.Webber at nbi.ac.uk>>
Date: Mon, 23 Jun 2014 11:20:08 +0000
To: William Moore <will at lifesci.dundee.ac.uk<mailto:will at lifesci.dundee.ac.uk>>
Cc: "ome-users at lists.openmicroscopy.org.uk<mailto:ome-users at lists.openmicroscopy.org.uk>" <ome-users at lists.openmicroscopy.org.uk<mailto:ome-users at lists.openmicroscopy.org.uk>>
Subject: Re: [ome-users] sessionid files in /tmp

Hi Will,

Thanks for the response.

I have done some more tests but am still experiencing the same issue.  I have restarted HTTPD, Omero and Omero_web.  I have also rebooted the server itself.

These files are created when we restart omero web.  When omero web is not running the files are not created.

I am running exactly the same python versions, omero versions and ice versions across two servers.  The main difference I can see on these servers is that the one which has “sessionid” files gathering in “/tmp” has a later version of httpd as follows:

                Server without issue:                                                     Server with sessionID issue:
httpd-2.2.3-82.el5.centos                                             httpd-2.2.3-83.el5.centos
httpd-devel-2.2.3-82.el5.centos                                                httpd-devel-2.2.3-83.el5.centos

I have attached a complete list of the different RPMs, but not sure whether any of the others are relevant.

Please can you give me a pointer as to why this is occurring.  Is it something that can be corrected, or do I need to set up a cron job to remove the session ID files?

Thanks
John

From: William Moore [mailto:will at lifesci.dundee.ac.uk]
Sent: 20 June 2014 10:46
To: John Webber (NBI)
Cc: ome-users at lists.openmicroscopy.org.uk<mailto:ome-users at lists.openmicroscopy.org.uk>
Subject: Re: [ome-users] sessionid files in /tmp

Hi John,

 It's probably the Django web server that is creating these files in /tmp. See https://docs.djangoproject.com/en/dev/topics/http/sessions/#using-file-based-sessions

and http://stackoverflow.com/questions/10197880/django-file-based-session-doesnt-expire

These are sessions between the browser and the Django server and have nothing to do with OMERO sessions.

Are you aware of any difference in the web server configurations or browser connections between your servers that could explain this behaviour?

 Regards,

   Will.

On 19 Jun 2014, at 16:38, "John Webber (NBI)" <John.Webber at nbi.ac.uk<mailto:John.Webber at nbi.ac.uk>> wrote:

Hi all,

On one of my Omero servers I am seeing “sessionid” files in /tmp, which are generated every 10 minutes and not removed. These files are called something like “sessionideb93037246a7b1efe7e01f6eec735cef”.  On other Omero servers, one or two of these files might exist, but they are not created every 10 minutes or so!  These are only small, but there are a lot of them!

Can anyone advise why these are being left behind?  This is the SAME server where I was experiencing the “Server error[500]” errors, which have now stopped.

Thanks
John

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