May 2003 - dovecot - dovecot.org

[Dovecot] Speed and memory probs writing large Maildir
by Robin Whittle 14 Jun '03

14 Jun '03

I have Dovecot 0.99.9.1 compiled from the source, without SSL, running on a Red Hat 9.0 system - EXT3 file system, Pentium Pro 233 MHz, Intel motherboard, 128M RAM, IBM 40Gig 7200 RPM HD. I find reading and searching to be nice and fast, and comparing it with Courier IMAP on a Celeron 824 MHz, I think Dovecot is generally not much slower, which means it may well be faster than Courier in some or many ways if it was running on the same machine. My only problem is when writing mailboxes with large numbers of messages. I use Mailir - the same arrangement as Courier IMAP. (I also find that Netscape 4.77 can't use mailboxes which are subfolders of others, but that is probably a Netscape config problem.) I am using Netscape 4.77 (Windows 2000 1.3 GHz Celeron, via 100Mbps switched Ethernet to the Linux machines) to do these tests since I find Netscape 7.02 to be much slower. Netscape 7.02 seems to want to resynch its notion of the mailbox repeatedly as it is writing to it. Without looking at the IMAP traffic (I don't know how) I would say that Netscape 4.77 is not doing this at all. Indeed, after the write, looking at the mailbox causes Netscape 4.77 to read the headers from the IMAP server - so I feel sure that its way of writing the messages is purely "write". Writing a mailbox with a small number of large messages, such as 20 x 100k messages is fine. There is no obvious speed problem or excessive memory use. When writing 2000 x 1k messages, it is totally different. Here are some times for writing from a Netscape 4.77 local mailbox to Dovecot and to Courier IMAP. Message Total Time CPU max Memory RSS size number size Seconds Approx Megs - max Dovecot 100k 100 10M 23 15% ~2 100k 20 2M ~5 ? 1.2 10k 200 2M 20 15% 4 ! 1k 2000 2M 230 60 32 !!!! Courier IMAP 100k 100 10M 14 5% ~1 100k 20 2M ~2 ? ? 10k 200 2M 9 5% ~0.6 1k 2000 2M 88 2% ~0.6 This 2000 message test is small compared to some of the mailboxes I have. I used a real-live mailbox, 6878 messages - 44 Megabytes in a single Mbox for a more demanding test. Using Netscape 4.77 to copy this to a Dovecot Maildir took a very long time - over 30 minutes. The process was fast at first and got slower and slower. As the number of messages in the destination Maildir increased, the memory usage went up and the speed reduced. It seems that RSS memory usage (as reported by "top -d 0.3" hit some kind of limit at about 49 Megs after 4000 messages and then went down a little to about 48 or less. CPU usage was 30 to 82%, fluctuating according to the moment top looked. At the end, I think it was only writing 1.5 messages a second. RSS is the "total amount of physical memory used by the task". The "SIZE" was even bigger - "code plus data plus stack". This got up to 114 Megs by the end of the writing process! After the write had finished, I made Netscape 4.77 view the destination mailbox. This caused Dovecot to send it all the headers, and again Dovecot had these huge memory usage figures. It seemed to read the mailbox at a decent speed - 20 seconds or so. But if I made Dovecot look at another mailbox, and then again at this big target mailbox (say with another client - Netscape 7), it would read the big mailbox at Dovecot's usual high speed - without the high memory usage and I think without high CPU usage as well. Without knowing anything about how Dovecot works, I imagine that there is some kind of caching algorithm for writes, and that this is retained until Dovecot (or at least the instance serving this client) is asked to look at another Maildir. It seems that reading is not slowed by this process much or at all - but writing gets progressively slower as the cache gets bigger. The memory usage - even 49 Megs for RSS - seems excessive. It reached that about halfway through writing the mailbox, so the entire message contents at that state would have been about 22 Megs. But the "SIZE" memory usage is even larger - perhaps limited by the available RAM. This slow speed for writing Maildirs with large numbers of messages is currently a barrier to me using Dovecot. I am about to go back and try again to get Courier IMAP to do what I want . . . The Courier IMAP documentation and what I regard as the difficult "configure -> build -> install -> wonder why it doesn't run" process has cost me so much time that I would be very happy to use something simpler and easier (for me, at least) to install. Thanks for developing this new IMAP server! - Robin

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[Dovecot] DRAC support?
by Charlie Allom 14 Jun '03

14 Jun '03

Hi, I was hoping someone had a quick and dirty (is there any other kind) of patch for DRAC support for dovecot. This daemon is very slick, and I wish to replace my complex courier-imap setup. Regards, C. -- charlie(a)rubberduck.com - Melbourne, Australia http://rubberduck.com/~yeled/ PGP: 0x14AA7941 || finger yeled(a)lazy.spodder.com > http://groups.google.com/groups?selm=3266D499.342E%40student.uq.edu.au <

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[Dovecot] dovecot 0.99.10-test10
by Andrew Basterfield 31 May '03

31 May '03

Hiya builds fine on BSD now (thanks) Now I am getting index corruption again May 30 03:11:53 snigger imap(bob): Corrupted binary tree file /home/bob/Mail/.INBOX/.imap.index.tree: UID to be inserted isn't higher than existing (1 <= 1) and so on until the client hangs test7 is stable here. Also what are the correct permissions for /var/run/dovecot/login? I get a message about correcting the permissions every time I start dovecot --Andrew -- http://cemetery.homeunix.org

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[Dovecot] the most serius problems [part 3]
by Farkas Levente 30 May '03

30 May '03

hi, so the third problem is ssl. the imaps is still not working (and I assume the same apply to pop3s too). I already send the log file which was generated when verbose ssl is set. -- Levente "Si vis pacem para bellum!"

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[Dovecot] the most serius problems [part 2]
by Farkas Levente 30 May '03

30 May '03

hi, the second thing is the webmail. we use squirrelmail. actualy I don't know whose fault is, but they told that them imap server's:-) first problems is that those mails which has empty body (even if they has an attachments) simple not shown in the mail list (as they even not exists). it'd be nice to check this and find the reason of the problem. this happend with more people. -- Levente "Si vis pacem para bellum!"

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[Dovecot] the most serius problems [part 1]
by Farkas Levente 30 May '03

30 May '03

hi, I try to collect out most serious problem with dovecot. so I write a series of mails:-) the first on is the load. has anybody else use dovecot in a real enviromnt with at least hundreds of users and at least 50 concurrent user at the same time? it seems to me no one else just me. the weekend I move the whole mail system to a quad P4 with 1Gb ram and this server do nothing just imap. yesterday evening I have to delete all .imap.index and other dovecot specific files. and as I wrote today morning the load was about 20-30 !!!. but even in an average day the load is over 2-3 white the cpu load is 1-2% in each of the 4 processor. the system is totaly unusable. what more today I've got other errors. of course all the time when I can't find the colution I try to escape to the latest cvs. today finally I compile a new courier install it to another port and those clients which can't connect to dovecot reconfigure to courier. but they are not compatible!!! I have to set root directory to INBOX in courier while not for dovecot and this is a real big problem. is there any way to compile dovecot to use INBOX as a root directory? since in this case at least there is a chance to switch to courier without reconfigure 300 OE6. I try to help to find out the reason for the load in any way, but it seems to me than it's better to change to courier or cyrus since our users getting angry not to mention my boss. -- Levente "Si vis pacem para bellum!"

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[Dovecot] 0.99.10-test8
by Timo Sirainen 30 May '03

30 May '03

http://dovecot.procontrol.fi/test/ Again major maildir syncing updates: - uidlist file is accessed and rewritten a lot less often now than before - mail duplicates are detected and handled properly by renaming them to new base name - message flag updates and expunging before did two full syncs for cur/ directory. now it does only one. - some fixes to syncing in read-only / out-of-quota conditions - before we did always a full sync in cur/ directory when mailbox was opened. now it's done only when needed. - fixed some crash/index corruption cases I think syncing should be now very close to having perfect possible performance.

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[Dovecot] new problems
by Farkas Levente 29 May '03

29 May '03

hi, so yesterday I move the whole mail system to a better machine. the only thing which is running on this system is dovect and: -------------------------------------------------- 10:44am up 6 days, 25 min, 3 users, load average: 28.03, 17.96, 9.05 233 processes: 231 sleeping, 2 running, 0 zombie, 0 stopped CPU0 states: 3.1% user, 29.4% system, 0.0% nice, 66.4% idle CPU1 states: 7.1% user, 63.2% system, 0.0% nice, 29.1% idle CPU2 states: 1.3% user, 3.1% system, 0.0% nice, 94.4% idle CPU3 states: 1.1% user, 7.4% system, 0.0% nice, 90.3% idle Mem: 1030496K av, 1021836K used, 8660K free, 0K shrd, 104064K buff Swap: 2040244K av, 55544K used, 1984700K free 776180K cached -------------------------------------------------- so the problem here is again with the load 28 (!!!)..... in the imap.log: -------------------------------------------------- imap(arvays): May 28 10:39:32 Error: Timeout while waiting for release of fcntl() lock for index file /home/arvays/Maildir/.INBOX/.imap.index imap(lfarkas): May 28 10:42:05 Panic: unreached dovecot: May 28 10:42:07 Error: child 19933 (imap) killed with signal 6 imap(ahegedus): May 28 11:05:57 Panic: file maildir-sync.c: line 472 (maildir_sync_uidlist): assertion failed: (ACTION(hash_rec) == MAILDIR_FILE_ACTION_NEW) dovecot: May 28 11:05:58 Error: child 29103 (imap) killed with signal 6 -------------------------------------------------- -- Levente "Si vis pacem para bellum!"

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[Dovecot] still has error
by Farkas Levente 28 May '03

28 May '03

hi, after download the current cvs recompile, start I still has these errors: ------------------------------------- imap-login: May 28 13:49:02 Info: Login: jcsinalos [192.168.0.106] imap(jcsinalos): May 28 13:49:02 Panic: unreached dovecot: May 28 13:49:02 Error: child 31683 (imap) killed with signal 6 imap-login: May 28 13:49:03 Info: Login: jcsinalos [192.168.0.106] imap-login: May 28 13:49:03 Info: Login: jcsinalos [192.168.0.106] imap(jcsinalos): May 28 13:49:03 Panic: unreached dovecot: May 28 13:49:03 Error: child 31687 (imap) killed with signal 6 ------------------------------------- -- Levente "Si vis pacem para bellum!"

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[Dovecot] 0.99.10-test7
by Timo Sirainen 28 May '03

28 May '03

- APPEND memory leak fixed - maildir syncing crash / some other errors fixed - pop3 mail fetching fixed - pop3 didn't advertise STLS in capabilities before http://dovecot.procontrol.fi/test/

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