[Dovecot] COMPRESS bug?

[Ed W]

On 09/11/2010 21:07, Timo Sirainen wrote:
> On Tue, 2010-11-09 at 19:20 +0000, Ed W wrote:
>> 36203 36204 36205 36206 36207 36208 36209 36210 36211
>> doveadm(root): Error: zlib.read(): unexpected EOF at 2489
>> I now restart the server (while the client sitting and hanging),
>> abbreviated output:
>> ....
>> 36207 36208 36209 36210 36211
>> 8 OK Search completed (0.381 secs).
> Yeah, looks like the "OK Search completed" gets stuck somewhere. Wonder
> if http://hg.dovecot.org/dovecot-2.0/rev/631e0d846e57 would help? I'm
> not too optimistic though.
>

OK, some time has passed, but now back and I have traced this to it 
being an issue once a folder gets a certain number of emails in it.

So to summarise:

- Zlib enabled
- COMPRESS initiated in the connection
- 30,000 messages in a single maildir folder
- IMAP SEARCH SINCE requested
- Dovecot 2.0.7 "hangs" without sending the closing stanza of the SEARCH 
result command
(exact imap trace in previous email in this thread)

IF
- Remove a single email from the folder (29,999 left) then everything 
completes successfully!

I have tested this with various permutations of 30,000 real emails and 
that seems to repeatably be the point problems occur.

(Note: A slight curiousity is that removing a single email to get things 
working, then adding the email back again sometimes seems to keep 
working, not sure why?  However, it's fairly easy to cause it to fail 
again, eg I moved ALL emails out of the folder, search, then add all 
emails back in again - now it starts to hang again.  Just mentioning 
this because there might be some ways that would stop you repro-ing it 
if you simply "add" emails to a folder until it breaks, rather than 
removing them from a folder which is already broken?)

Grateful if you can figure out the underlying problem in Dovecot?

Many thanks

Ed W