[Dovecot] Dovecot imap processes pinning CPU
In recent days, dovecot's "imap" processes keep getting stuck. Each time I check my server (running dovecot 1.1.7) there's a bunch of "imap" processes (sometimes 2 of them, sometimes 4, sometimes 6) that are using all of the box's CPU.
And worse, there's no way to kill the processes either (neither kill -15 or kill -9 works), which means that I wind up having to reboot the box every time this happens. REALLY irritating.
I don't normally even *see* the imap processes in htop, as I think they're pretty short lived. And I'm not sure what they're looping trying to do. My debugging skills on Linux are a bit weak, and so I don't know how to look at the process and see what it's doing.
Also, not sure what's changed on my system to cause this, as this is definitely a recent problem. Maybe the upgrade to Thunderbird 2.0.0.18 (since I usually use T'Bird to access my email). I don't seem to run into this problem when I use Squirrelmail.
Anyone have any idea what the problem might be? Or, if not, then suggestions on how I might be able to debug the situation myself?
TIA,
DR
On Dec 13, 2008, at 3:40 AM, David Rosenstrauch wrote:
In recent days, dovecot's "imap" processes keep getting stuck. Each
time I check my server (running dovecot 1.1.7) there's a bunch of
"imap" processes (sometimes 2 of them, sometimes 4, sometimes 6)
that are using all of the box's CPU.And worse, there's no way to kill the processes either (neither kill
-15 or kill -9 works), which means that I wind up having to reboot
the box every time this happens. REALLY irritating.
I wonder what's going on. You're the 3rd person who has started a
thread about this within a few days. See the "unkillable imap
process(es) with high CPU-usage" thread that's going on, with the
exact same issue..
http://dovecot.org/list/dovecot/2008-December/035662.html
I don't normally even *see* the imap processes in htop, as I think
they're pretty short lived.
Depends on the clients, but many clients keep IMAP connections open
for a long time, so the imap processes should be long living.
What distribution and kernel version are you using?
On Sat, December 13, 2008 12:28 am, Timo Sirainen wrote:
On Dec 13, 2008, at 3:40 AM, David Rosenstrauch wrote:
In recent days, dovecot's "imap" processes keep getting stuck. Each time I check my server (running dovecot 1.1.7) there's a bunch of "imap" processes (sometimes 2 of them, sometimes 4, sometimes 6) that are using all of the box's CPU.
I wonder what's going on. You're the 3rd person who has started a thread about this within a few days. See the "unkillable imap process(es) with high CPU-usage" thread that's going on, with the exact same issue.. http://dovecot.org/list/dovecot/2008-December/035662.html
Wow. Yeah, *some*thing's changed recently to cause this. If I had to guess, I'd say it's a recent Thunderbird upgrade that's triggering it, as it's been 2-3 weeks since my last dovecot upgrade.
I'll take a look at that thread.
What distribution and kernel version are you using?
Arch Linux, kernel 2.6.27.8
Thanks,
DR
On Sat, December 13, 2008 9:14 am, David Rosenstrauch wrote:
Wow. Yeah, *some*thing's changed recently to cause this. If I had to guess, I'd say it's a recent Thunderbird upgrade that's triggering it, as it's been 2-3 weeks since my last dovecot upgrade.
Or perhaps it's a recent kernel upgrade, since I see a number of people here seem to think it's a kernel issue.
What distribution and kernel version are you using?
Arch Linux, kernel 2.6.27.8
Thanks,
DR
David Rosenstrauch wrote:
Wow. Yeah, *some*thing's changed recently to cause this. If I had to guess, I'd say it's a recent Thunderbird upgrade that's triggering it, as it's been 2-3 weeks since my last dovecot upgrade.
Some other interesting data points:
This problem seems to happen when I use Thunderbird (both on Linux and Windows) as my MUA, but not with Squirrelmail.
The IMAP process seem to start going haywire when I shut Thunderbird down.
DR
Wow. Yeah, *some*thing's changed recently to cause this. If I had to guess, I'd say it's a recent Thunderbird upgrade that's triggering it, as it's been 2-3 weeks since my last dovecot upgrade.
Some other interesting data points:
This problem seems to happen when I use Thunderbird (both on Linux and Windows) as my MUA, but not with Squirrelmail.
The IMAP process seem to start going haywire when I shut Thunderbird down.
Thunderbird would use the inotify stuff, but I don't think squirrelmail does since it's web based.
On the installation where a pinned process is, the 2 people accessing that maildir are using Outlook. They both use Outlook.
One of them has the specific version: Microsoft Office Outlook 2007 (12.0.6316.5000) SP1 MSO (12.0.6320.5000)
And I'm sure the other one will have some version of Outlook 2007, but I haven't been able to get in touch with them yet.
David Rosenstrauch wrote:
On Sat, December 13, 2008 12:28 am, Timo Sirainen wrote:
On Dec 13, 2008, at 3:40 AM, David Rosenstrauch wrote:
In recent days, dovecot's "imap" processes keep getting stuck. Each time I check my server (running dovecot 1.1.7) there's a bunch of "imap" processes (sometimes 2 of them, sometimes 4, sometimes 6) that are using all of the box's CPU. I wonder what's going on. You're the 3rd person who has started a thread about this within a few days. See the "unkillable imap process(es) with high CPU-usage" thread that's going on, with the exact same issue.. http://dovecot.org/list/dovecot/2008-December/035662.html
Wow. Yeah, *some*thing's changed recently to cause this. If I had to guess, I'd say it's a recent Thunderbird upgrade that's triggering it, as it's been 2-3 weeks since my last dovecot upgrade.
I'll take a look at that thread.
Another data point:
I do not see this problem on multiple installations of 1.1.7 on FreeBSD 6.3. Clients are Thunderbird 2.0.0.18, Horde-IMP 4.3, Horde-DIMP 1.1, Roundcube 0.2.b and SquirrelMail 1.4.17.
Just saw this thread on http://dovecot.org/list/dovecot/2008-December/035707.html and I hope that this email gets through (I'm not subscribed).
The described behaviour seems to be a bug in Linux 2.6.27.8: http://lkml.indiana.edu/hypermail/linux/kernel/0812.1/00006.html
This fix seems to work for me: http://lkml.indiana.edu/hypermail/linux/kernel/0812.1/00998.html
It is not fixed in 2.6.27.9, but will be fixed in 2.6.27.10 according to Greg KH: http://lkml.org/lkml/2008/12/14/162
Hope that helps Steffen
On Mon, 15 Dec 2008, Steffen Weber wrote:
Just saw this thread on http://dovecot.org/list/dovecot/2008-December/035707.html and I hope that this email gets through (I'm not subscribed).
The described behaviour seems to be a bug in Linux 2.6.27.8: http://lkml.indiana.edu/hypermail/linux/kernel/0812.1/00006.html
This fix seems to work for me: http://lkml.indiana.edu/hypermail/linux/kernel/0812.1/00998.html
It is not fixed in 2.6.27.9, but will be fixed in 2.6.27.10 according to Greg KH: http://lkml.org/lkml/2008/12/14/162
Hope that helps Steffen
Thanks, I've cancelled the bisect I was doing after hitting a kernel panic today. Not so good to do one on a production box unfortunately.
I will try that patch.
Steffen Weber wrote:
Just saw this thread on This fix seems to work for me: http://lkml.indiana.edu/hypermail/linux/kernel/0812.1/00998.html
That fixed it for me as well. You can get the patch from gitweb at (formatting is a bit nicer for patching):
http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=...
It is not fixed in 2.6.27.9, but will be fixed in 2.6.27.10 according to Greg KH: http://lkml.org/lkml/2008/12/14/162
Good, I guess we just picked the wrong time to update our mail server to the latest stable kernel.
That fixed it for me as well. You can get the patch from gitweb at (formatting is a bit nicer for patching):
http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=...
It is not fixed in 2.6.27.9, but will be fixed in 2.6.27.10 according to Greg KH: http://lkml.org/lkml/2008/12/14/162
Good, I guess we just picked the wrong time to update our mail server to the latest stable kernel.
That patch seems to have fixed it for me too
participants (6)
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Darren Pilgrim
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David Rosenstrauch
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nuitari-dovecot＠nuitari.net
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Patrick McLean
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Steffen Weber
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Timo Sirainen