High cpu usage for imapd processes on 2.4.12 (Invoca rpm)

[Bron Gondwana]

On Fri, Nov 11, 2011 at 04:23:47PM +0000, Guy wrote:
> The original machine is running 2.3.16 without replication and the
> average load rarely went over 1. On the new server running 2.4.12
> (details below) I'm seeing the average load hover around 5 constantly.
> The new box is running replication and this appears to be set up
> correctly as the logs look pretty clean. top shows CPU percentage for
> each imapd process running quite high. The largest mailbox contains
> about 3000 emails and is usually at 50 to 60% CPU.

I wonder if it's crc32 causing the difference.  The replication will
be adding some load too.

And yes - you really want expunge_mode: delayed if you're running
replication, or at least NOT expunge_mode: immediate.

> expunge_mode: default

That should be OK actually.
> server101_sync_host: 10.10.10.10
> server201_sync_host: 10.11.10.11

You are syncing to two different backends.  That will be using more
CPU for sure, just because the same mailbox gets opened three times
for every change.

Bron.