[Dovecot] problem with uidlist

[Cor Bosman]

In both 1.2.6 and 1.2.7  (probably also before that, but dont have logs) im seeing quite a few of these:

Nov 17 12:45:12 userimap10.xs4all.nl dovecot: IMAP(xxxxxxx): /var/spool/mail/dovecot-control/c/c0/xxxxxxx/INBOX/.INBOX/dovecot-uidlist: Duplicate file entry at line 2650: 1257768394._smtp.mxdrop238.41874,S=17304:2,Sad (uid 34270 -> 37166)

I never really looked at it because it doesnt seem to be causing many problems, but i just noticed something that probably hints at the cause..

Nov 17 12:45:12 userimap10.xs4all.nl dovecot: IMAP(xxxxxxx): /var/spool/mail/dovecot-control/c/c0/xxxxxxx/INBOX/.INBOX/dovecot-uidlist: Duplicate file entry at line 2650: 1257768394._smtp.mxdrop238.41874,S=17304:2,Sad (uid 34270 -> 37166)
Nov 17 12:45:12 userimap10.xs4all.nl dovecot: IMAP(xxxxxxx): /var/spool/mail/dovecot-control/c/c0/xxxxxxx/INBOX/.INBOX/dovecot-uidlist: Duplicate file entry at line 2651: 1257769385._smtp.mxdrop155.53889,S=305996:2,Sad (uid 34271 -> 37167)
Nov 17 12:45:12 userimap10.xs4all.nl dovecot: IMAP(xxxxxxx): /var/spool/mail/dovecot-control/c/c0/xxxxxxx/INBOX/.INBOX/dovecot-uidlist: Duplicate file entry at line 2652: 1257769984._smtp.mxdrop107.23815,S=320781:2,Sabd (uid 34272 -> 37168)
Nov 17 12:45:12 userimap10.xs4all.nl dovecot: IMAP(xxxxxxx): /var/spool/mail/dovecot-control/c/c0/xxxxxxx/INBOX/.INBOX/dovecot-uidlist: Duplicate file entry at line 2670: 1257858287._smtp.mxdrop131.43563,S=26827:2,Sad (uid 34311 -> 37186)
Nov 17 12:45:12 userimap10.xs4all.nl dovecot: IMAP(xxxxxxx): /var/spool/mail/dovecot-control/c/c0/xxxxxxx/INBOX/.INBOX/dovecot-uidlist: Duplicate file entry at line 2671: 1257858303._smtp.mxdrop238.88513,S=2143:2,Sad (uid 34312 -> 37187)
Nov 17 12:45:12 userimap10.xs4all.nl dovecot: IMAP(xxxxxxx): /var/spool/mail/dovecot-control/c/c0/xxxxxxx/INBOX/.INBOX/dovecot-uidlist: Duplicate file entry at line 2672: 1257858868._smtp.mxdrop217.21298,S=8548:2,Sad (uid 34314 -> 37188)
Nov 17 12:45:12 userimap7.xs4all.nl dovecot: IMAP(xxxxxxx): /var/spool/mail/dovecot-control/c/c0/xxxxxxx/INBOX/.INBOX/dovecot-uidlist: Duplicate file entry at line 994: 1244800736._smtp.mxdrop237.59318,S=4573:2,Sad (uid 32467 -> 35510)
Nov 17 12:45:12 userimap7.xs4all.nl dovecot: IMAP(xxxxxxx): /var/spool/mail/dovecot-control/c/c0/xxxxxxx/INBOX/.INBOX/dovecot-uidlist: Duplicate file entry at line 995: 1244807927._smtp.mxdrop215.53275,S=439887:2,Sad (uid 32468 -> 35511)
Nov 17 12:45:12 userimap7.xs4all.nl dovecot: IMAP(xxxxxxx): /var/spool/mail/dovecot-control/c/c0/xxxxxxx/INBOX/.INBOX/dovecot-uidlist: Duplicate file entry at line 996: 1244828590._smtp.mxdrop111.81795,S=3606:2,RSabd (uid 32469 -> 35512)

This customer seems to be using our IMAP service from 2 machines at the same time. Possibly a webmail service and a desktop imap client. It may be that both machines are trying to manipulate the uidlist at the same time, causing who knows that kind of corruption. This could maybe explain some of the coredumps im seeing in 1.2.7? 

This is on Debian/Lenny, using NFS spool and NFS control/indexes. 

Timo, you asked in private mail a few days ago if we're sure the filenames are forever unique. Im sure. I double checked it in the source code. The above filenames are timestamp_hostname.pid, and that seems pretty unique right?

Regards,

Cor