My users are having problems with their IMAP mailboxes. The IMAP processes are hanging and timing out. When they timeout, the users might see an empty email box.
But the real problem appears to be the communication between slapd and famd.
- Debian Lenny
- courier-imap 4.4.0-2
- fam 2.7.0-13.3
- slapd 2.4.11-1
passwd: files ldap group: files ldap shadow: files ldap
courier's imap configuration file contains "IDLE" in the capabilities but removing it (and fiddling with IMAP_ENHANCEDIDLE) does nothing. From reading up, I would have thought that this would have stopped courier imap from using fam, but I guess not.
stracing the imap process (when it hangs) shows it hanging on communication with fam. So I restarted fam (which fixed the problem for a few hours) and continued trouble shooting to find the root of the problem.
Since the program was still hanging, I kept looking.
stracing famd showed it was hanging on communication with slapd. Kicking slapd solved the problem for a bit. slapd was responsive to other queries, but did become slower over time.
The strangest thing is these problems just started popping up. And the only packages that I've upgraded that I think might be relevant are the following:
base-files 5lenny4 libmysqlclient15off 5.0.51a-24+lenny2 libssl0.9.8 0.9.8g-15+lenny3 openssl 0.9.8g-15+lenny3 tzdata 2009l-0lenny1 udev 0.125-7+lenny3
It appears (without me confirming this yet) that the connection between famd and slapd is a long-lived one (via nscd).
Oops, writing this I just realized nscd is another piece I haven't tested. Guess I'll look into that.
EDIT: Just confirmed that kicking nscd solves the problem, too.