D4Science Infrastructure

@tommaso.piccioli@isti.cnr.it has noticed under '/tmp/[ckan_name]/sessions' directory that milions of file are created by CKAN.
Investigating the issue we have found (from https://lists.okfn.org/pipermail/ckan-dev/2015-February/008648.html) the following one:

The cache directory or the session directory is only used for stuff that is not saved in the database.  
It is always safe to remove.  It is only used for very temporary data.
CKAN only uses it in fact to store the little popup messages that come up after you are redirected to a new page.

... but those files are never deleted.

We need and can (in order to avoid filling the disk) to pass from caching on disk to cacking in memory by installing
and configuring memcached (see at https://github.com/memcached/memcached) for pylons and beaker.

How to install and use it:

https://stackoverflow.com/questions/13781023/how-to-configure-ckan-to-store-sessions-somewhere-other-than-disk-e-g-db-or-me

https://beaker.readthedocs.io/en/latest/sessions.html#deleting