531554 - High IMAP server load (large mail store/1.7GB)

Status: RESOLVED INVALID

(Thunderbird :: General, defect)

Description

[Tony Jacobs]

User-Agent:       Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.9.1.5) Gecko/20091102 Firefox/3.5.5
Build Identifier: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.9.1.5) Gecko/20091121 Lightning/1.0b1pre Thunderbird/3.0

After migrating to thuberbird 3.0 rc1, I've noticed that my mail server (Linux, running Dovecot 1.0.7) is running an unusually high load on a 5 minute interval, which happens to be Thunderbird's refresh interval.

At first, I thought this might be related to synchronization, so I disabled that (and I set the max cache size to 4GB so it wouldn't need to re-download my mail).  Once I disabled syncronization, I noticed that the packet traffic went way down, but the CPU load was not affected.

The status bar seems to report a Reindexing every few minutes (even when no new mail is received) 

I'm also noticing that the status bar seems to be reporting 'Searching folder...' while the load is high, but this could be a red herring -- I have to click through the folders to make it show up.

I've got the nightly (2009.11.21) lightning installed (no other extensions), although that should not be affecting anything

Reproducible: Always

Steps to Reproduce:
1. Run Thunderbird 3.0 rc1
2. Use IMAP for a large set of folders
3. Enable bayesian spam filtering, sending matches to a Suspect folder
4. Let computer sit idle
Actual Results:  
Server CPU should be mostly idle with no spikes with an 1 minute load average increasing by 1-2 every 5 minutes (implying a 100% CPU load (or more!) on the same periodic as the IMAP mail refresh).

Expected Results:  
Not that! -- a fast linux server should not break a sweat for a single user checking email

Comment 1

[Tony Jacobs]

The release notes for Dovecot 1.0.8 (which I'm NOT yet running) say the following:

v1.0.8 2007-11-28  Timo Sirainen <[e-mail]>
...	- IMAP: Partial body fetching was sometimes non-optimal, causing
	  the entire message to be read for every FETCH command.


Could this be the problem that I'm seeing?  I'll try upgrading the server to see if this fixes the load problem.  Dovecot 1.0.7 is in the default Red Hat Enterprise Linux 5 release.

Comment 2

[Tony Jacobs]

Not thunderbird