[Dovecot] stale locks

[Thomas Hummel]

Hello Timo,

I'm running 

  dovecot-1.0.rc15 (imap and pop)
  postfix-2.3.5,1
  procmail-3.22_6 (which is my LDA)

on FreeBSD 6.1-STABLE

I'm still using the mbox format (I'm planning to migrate to Maildir
soon), mailboxes are on an NFS filesystem.

I regulary see stale dotlocks files (either from dovecot (29 bytes,
hold the pid of the process) or procmail (1 byte) and processes
stucked in Disk Wait state.

The only way I can get ridd of them is to
	
	restart nfslocking
	remove the .lock file
	change the inode of the mailbox file
	
locking strategies are

	fcntl for mbox_read in dovecot
	dotlock fcntl for mbox_write in dovecot
	dotlock fcntl for procmail

so I can't figure out why I see such stale locks and processes. 

Note : I disabled nfs attribute caching so I avoid cache related
issues (such as a dotlock showing up late, etc...)

Besides, I often see several imap-login processes for the same remote
IP address. Does it means the user has several instances of his UA
running or is it the behavior of some UA (Eudora ? Thunderbird ?) even
if only one instance is run by the user. In any case, wouldn't that be
dead-lock/stale lock prone ?

-- 
Thomas Hummel 	    | Institut Pasteur
<hummel at pasteur.fr> | Pôle informatique - systèmes et réseau