On Mon, Jun 16, 2014 at 9:08 AM, Daniel Barrett <[email protected]> wrote: > In the past few weeks, we've been seeing the "Loss of session data" error > message in our wiki frequently when users try to save their edited articles > (and the save fails). Our best guess is that memcached, which stores session > info, is losing session information unexpectedly. This began shortly after > upgrading from MediaWiki 1.21 to 1.22 (I don't know if this is related, but > the timing is suspicious). When users log out and log back in, the error goes > away... for a time. > > What is the recommended way to debug this kind of problem? What would YOU do > if this issue cropped up on your wiki? > > We've been inserting error_log() statements into MediaWiki core code, dumping > the values of $_SERVER, $_COOKIE, and $_SESSION, and haven't found anything > helpful yet. > > Our wiki (version 1.22.5) is served by four webservers behind a load > balancer on a private intranet. There's a master and one slave database. > memcached has plenty of RAM and therefore should not be dropping data.
Is memcached setup to use all of the memory? You can get pretty good stats out of it (or used to, bad in my ops days). That prove it's not dropping things out of cache. Also, make sure it's not a mismatch of the edit token (which is several places gives an error saying the session was lost, but could be because the session token was actually updated, like if the user logs out from another browser. > > Thanks for any helpful debugging tips! > DanB > > > > _______________________________________________ > MediaWiki-l mailing list > [email protected] > https://lists.wikimedia.org/mailman/listinfo/mediawiki-l _______________________________________________ MediaWiki-l mailing list [email protected] https://lists.wikimedia.org/mailman/listinfo/mediawiki-l
