Slow reading of large dovecot-uidlist files

Adrian Minta adrian.minta at
Sun Apr 10 08:27:15 UTC 2016

It will be nice if the "SELECT MyMailbox" command will be "SELECT 
mymailbox LIMIT 100" or something, to get the first files since only the 
last messages are shown to the user.
I don't know if "Limit" clause is available over IMAP.

On 04/09/2016 09:04 PM, Bostjan Skufca wrote:
> Hi there,
> (context: I was optimizing Roundcube mailbox list server response, and in
> that 300-400ms response time, around 170ms is spent on single fgets() call
> which is waiting IMAP repsonse to "SELECT MyMailbox" command)
> I straced dovecot and of the whole request/response process, around 30ms is
> spent for everything else, and overwhelming majority of time (150-170ms) is
> spent for reading dovecot-uidlist file for given mailbox.
> I skimmed over src/lib-storage/index/maildir/maildir-uidlist.c
> and src/src/lib/istream.c, but I am out of ideas on how to optimize
> mentioned file reading elegantly to make it faster.
> Is there any way to cache parsed content of uidlist file(s) or some other
> obvious quicktrick I am missing to speed this process up?
> Does anyone have any other ideas, how to speed this up?
> b.

Best regards,
Adrian Minta

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