https://bugzilla.wikimedia.org/show_bug.cgi?id=71645
Bug ID: 71645
Summary: php5 session cleanup script can go nuts
Product: MediaWiki-Vagrant
Version: unspecified
Hardware: All
OS: All
Status: NEW
Severity: normal
Priority: Unprioritized
Component: General
Assignee: wikibugs-l@lists.wikimedia.org
Reporter: bda...@wikimedia.org
CC: dduv...@wikimedia.org, o...@wikimedia.org,
yuvipa...@gmail.com
Web browser: ---
Mobile Platform: ---
I think I may have tracked down a cause of Trusty VMs (and labs instances)
occasionally locking up.
The php5 package shipped with Ubuntu 14.04 includes a cron job to cleanup stale
session files stored on disk. A similar cron job has been present in previous
versions of Ubuntu, but the version shipped with 14.04 attempts to fix a long
standing bug <https://bugs.debian.org/626640> by scanning for sessions in
active use before purging. To do this, the upstream maintainer decided that
running `/usr/bin/lsof -w -l +d "/var/lib/php5"` would be a great way to find
out if any processes had session files open. As pointed out in an upstream bug
report <https://bugs.launchpad.net/ubuntu/+source/php5/+bug/1356113> lsof can
have a highly variable runtime cost depending on the processes running at the
time it is invoked. I have now several times caught multiple versions of the
/usr/lib/php5/sessionclean script running on my VM. Since this script is only
invoked at :09 and :39 of each hour by cron, if multiple instances are seen
this implies that the older version has been running for at least 30 minutes.
The Ubuntu 12.04 version of the cleanup script was inlined in /etc/cron.d/php5:
[ -x /usr/lib/php5/maxlifetime ] && [ -d /var/lib/php5 ] && find
/var/lib/php5/ -depth -mindepth 1 -maxdepth 1 -type f -cmin
+$(/usr/lib/php5/maxlifetime) ! -execdir fuser -s {} 2>/dev/null \; -delete
The proposed fix in the upstream Debian package is at
<http://anonscm.debian.org/cgit/pkg-php/php.git/tree/debian/sessionclean>. This
fix is not currently scheduled for backporting to Ubuntu 14.04.
I think we should either, 1) revert the cron job to the 12.04 version, 2)
backport the Debian fix as part of our Puppet configuration, or 3) remove the
clean up job entirely as part of our Puppet configuration.
Since we do not currently set $wgSessionsInObjectCache, we are actively using
files to store php sessions. I think this implies that option 3 would be less
than optimal.
--
You are receiving this mail because:
You are the assignee for the bug.
You are on the CC list for the bug.
_______________________________________________
Wikibugs-l mailing list
Wikibugs-l@lists.wikimedia.org
https://lists.wikimedia.org/mailman/listinfo/wikibugs-l
