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bperkins

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About once a week, I'll get a 100% CPU spike that will occur until KMS is restarted. I haven't contacted support about this yet, because I have no idea what causes this. I don't know if it is something in the webmail or the KOC or IMAP.

Has anyone else experienced this? This has been happening from KMS 6.0.0 - 6.0.4.

Thanks,
BP
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desquinn

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running on a customised RH9 distro with KMS 6.04 now. Have had no spikes with this installation. Had a few issues with too many IMAP connections but this did not affect performance. Just caused a DOS on Outlook connectivity :)


Des Quinn
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johbar

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I myself haven't had this problem but think I am experiencing a similar problem.

KMS runs smoothly for a couple of hours then takes all processing power and freezes with the error:

[21/Nov/2004 12:27:05] list.cpp: Cannot start mail exchange thread:(12) Cannot allocate memory

I have to restart the KMS as it refuses to restart itself. I think the problem has to do with not enough memory in the server itself. I have a P4 2.8 gHz | 2 X 512 MB (duel channel) | 200 GB server and this problem does not accur.

On the server that the problem does persist only has 256 MB(PCC 133 2 X 128 MB) mem installed.

Mother is the name for God on the lips and hearts of all children
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KellyMc

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We've seen a lot of this on OSX running on a Dual G5 Xserve.

Initially, it was a problem with the spam filter -- some message would stick in the filter and we'd have to rename the mail queue and restart. Patches that I'm told are incorporated in 6.04 seemed to clear this up.

Now, we're getting severe CPU spikes when users attempt to delete or move a large number (it's happened with as little as 300) messages.

Just in the past couple of days, I've seen huge spikes (top reports the mailserver using 4,000+%, whatever that means) accompanied by the queue stopping completely and filling up. Restarts haven't helped, but I just resolved one a few minutes ago by turning off SpamAssassin.

Kerio Mailserver: it really keeps you on your toes.
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bperkins

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I have narrowed this down a little on my end......

One particular user on my system is causing the CPU to spike to 100% and only a KMS restart gets it back down. The user uses Outlook Express, IMAP (not IMAPS).

I don't know what this user is doing to cause this. I'm supposed to look at their setup next week.

KMS 6.0.4
RHE3

Anyone using OE/IMAP and have experienced this?

Thanks,
BP
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KellyMc

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You might try having the user move several hundred messages to trash and see if that does anything.

It seems particularly bad with users using OS X Mail App. It seems to get into some sort of loop as it waits for the server to move the messages and will lock up the user's account and cause CPU spikes.
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mdhmi

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KellyMc wrote on Mon, 22 November 2004 12:38

...
I've seen huge spikes (top reports the mailserver using 4,000+%, whatever that means)


Are you running Linux on a dual processor box? Remember that the system will treat each processor as two CPU's (even does that in Windows XP) and thread accordingly. Just a guess.

Cheers,

Mark




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KellyMc

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Another thing I'm curious about. When a user does these big moves/deletes, the debug log fills up with ...


03/Dec/2004 15:06:42][74680832] {ldapdb} user<_at_>domain: Looking up in cache...

[03/Dec/2004 15:06:42][74680832] {ldapdb} user<_at_>domain: found in cache


seemingly one for each message moved. Why does it have to query the ldap cache for each one? Is there a way to prevent that?


mdhmi wrote on Fri, 03 December 2004 06:08

Are you running Linux on a dual processor box?


It's OS X on a dual processor. I know it will report 200% when both processors are maxed out, but higher and sometimes negative (I've seen -1900%) loads seem like overload glitches to me.
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KellyMc

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A little more on this ...

The CPU load seems to be the result of the server having to process each message as its body is downloaded to the client, then uploaded to the user's trash folder on the server. When these mass deletions happen, we see spikes in messages received and SMTP activity and the message queue seems to process ("local delivery" and "backup") each message.

Seems like most of the server load would disappear if the server could move the messages directly to the trash without going through the client. Is that just a fact of IMAP?
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bperkins

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KellyMc wrote on Fri, 03 December 2004 15:50

A little more on this ...

The CPU load seems to be the result of the server having to process each message as its body is downloaded to the client, then uploaded to the user's trash folder on the server. When these mass deletions happen, we see spikes in messages received and SMTP activity and the message queue seems to process ("local delivery" and "backup") each message.

Seems like most of the server load would disappear if the server could move the messages directly to the trash without going through the client. Is that just a fact of IMAP?



Now, this is a little different than my situation. It sounds as if your CPU only goes up to 100% during the heavy load of the activity. My CPU will not go down, unless of a restart of KMS (even during off hours it will still be 100%). Now, mine might be caused by the same thing, I don't know yet. All I know on my situation is that the culprit is an Outlook Express/IMAP user. When it stays at 100%, there are a bunch of IMAP connections from this user under the active connections tab in the admin console. The connections will still be active even when they are not in OE anymore. This is all I know so far.

BP
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KellyMc

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Well, we upgraded to 6.04 from 6.03 on Friday and now the processors seem to consistently hover around 100%, regardless of activity. Turning off Spam filtering doesn't seem to have any effect on the processors as it used to. (Strangely, the load now seems to be mainly on one processor, where before it was distributed equally.)

Also similar to your situation, today I had a Mozilla user who would appear to have an active connection even after closing his client. When he tried to reconnect, it would hang while authenticating and create a new active connection. Eventually he had 10-20 active connections, and I had to restart the server to get rid of them and allow him to connect.

He suspected it began when he tried to delete a message from his Junk folder. I renamed his Junk E-mail folder before I restarted, the server created a new one and the problem has not recurred.
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bperkins

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KellyMc wrote on Mon, 06 December 2004 17:11

Well, we upgraded to 6.04 from 6.03 on Friday and now the processors seem to consistently hover around 100%, regardless of activity. Turning off Spam filtering doesn't seem to have any effect on the processors as it used to. (Strangely, the load now seems to be mainly on one processor, where before it was distributed equally.)

Also similar to your situation, today I had a Mozilla user who would appear to have an active connection even after closing his client. When he tried to reconnect, it would hang while authenticating and create a new active connection. Eventually he had 10-20 active connections, and I had to restart the server to get rid of them and allow him to connect.

He suspected it began when he tried to delete a message from his Junk folder. I renamed his Junk E-mail folder before I restarted, the server created a new one and the problem has not recurred.




Ok, this is starting to sound similar to my problem now. Can you submit a bug report to Kerio on this? I've submitted a bug, but don't have enough info to give them right now. Maybe if they have more people to get info from, they will be able to narrow it down and fix the problem.

So far, I have banned this user from using Outlook Express/IMAP and forced them to use webmail. My CPU load has been just fine since then.

Thanks,
BP
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KellyMc

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bperkins wrote on Tue, 07 December 2004 14:19

Can you submit a bug report to Kerio on this?


Done.
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bperkins

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I'm slowly beginning to narrow down my problem with KMS 6.x.x and it all points to the IMAP protocol.

A while back (when 6.0.0 or 6.0.1 was released) I had a user get locked out of his account while he was using the KOC. He could not open Outlook nor could he log in via webmail. At this time, I looked on the server and the server was at 100% CPU usage. I restarted KMS, the CPU went down, and he could then login just fine. Hmmmm. At the time, I just understood it to be a bug in the KOC.

During the course of using 6.x.x I would consistently get KMS using 100% of the CPU, thinking it was the KOC causing this. This kind of got better with 6.0.2 and 6.0.3. It didn't happen quite as often.

When I first installed 6.0.4, I kept getting 100% CPU almost on a daily basis. I was able to narrow it down to a particular user that was causing this. This person was using Outlook Express/IMAP. This person was also locked out of their account one time, just like the KOC incident. A restart of KMS unlocked their account.

The thing these two users had in common was using the non-secure IMAP. I have since switched them to using the secure protocol in the KOC and Outlook Express - IMAPS.

Now, my KMS has been up for 7 days straight with no problems. It has never been up for this long without having to restart KMS with a CPU 100% usage problem. It would never stay up for more than 2 days without 100% usage.

I will report this in my bug reports.

I hope this helps others......

BP
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bperkins

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Switching all IMAP connections to IMAPS have solved all my problems with KMS.

This was the cause of Outlook crashing periodically using the KOC along with Outlook Express crashes.

My KMS has been up for 10 days straight without having to restart and it is running just fine :-) This is a first for me since 6.x.x was released. I never could go 2 days without restarting. For now, I just turned off the IMAP service.

6.0.4 (Redhat Linux version).

KellyMC, are you using IMAP? If so, switch to IMAPS :-) This might solve your problem.

BP

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