Had to tweak statusnet.ini to remove the DB_DATAOBJECT_MYSQLTIMESTAMP bitfield constant on session.modified; while it sounds like a useful and legit setting, it actually just means that DB_DataObject silently fails to pass through any attempts to explicitly set the value. As a result, MySQL does its default behavior which is to insert the current *LOCAL* time, which is useless.
This was leading to early GC west of GMT, or late GC east of it. Early GC could at worst destroy all live sessions (whoever's session *triggered* GC is fine, as the session then gets saved right back.)
Big thanks to the folks at http://pecl.php.net/bugs/bug.php?id=16745 for the secret juju!
Classes were being torn down before session save handlers got called at the end of the request, which exploded with complaints about being unable to find various classes.
Registering a shutdown function lets us explicitly close out the session before everything gets torn down.
