[Dovecot] Strange Dovecot Issue with 64-bit AMD Processor

[Frank Bonnet]

Gene Steinberg wrote:
> Folks, I welcome your insights into a strange issue that may involve a
> memory leak, but certainly involves a repeatable server crash.
> 
> I have Dovecot installed as part of a cPanel installation. I think
> they're using 1.1.6 rather than the latest version, because they claim
> to need to test compatibility with their server software before
> deploying these components.
> 
> In any case, I set up the latest cPanel on a 64-bit server running two
> quad-core AMD Opteron 2352 processors and CentOS 5.2 (64-bit).
> 
> When I switch from the default Courier IMAP server to Dovecot, within 3
> to 8 hours, IMAP resource usage will spike and ultimately the server
> will freeze. Restarting and returning to Courier solves the problem.
> 
> The symptom is see in Top is that IMAP consumes 100% of memory, and the
> normal load (ranging from .05 to 1.50) soars to unheard of heights, such
> as 25, 50. Nothing will work on the server, which forces me to restart.
> 
> Our email load is reasonably light, and all the sites on the server are
> mine.
> 
> I have done fresh installs of cPanel and fresh updates without a
> solution. My server admin and cPanel support both appear stumped over
> this issue.
> 
> While I am hesitant to install a newer version of  Dovecot
> independently, I wanted to know if you're aware of any such
> difficulties. Since I'm back with Courier now, I presume logs aren't
> available (if they are let me know). But I never have problems with
> Courier, ever. I had Dovecot running fine with cPanel on a 32-bit
> Core2Duo server I use strictly for backup.
> 
> I appreciate the lightweight footprint of Dovecot and its performance
> advantages, but if I can't get it to work on my server, I can't use it.
> 
> Now maybe your newer versions solve this. Regardless, please provide
> whatever insights you can that might assist in tracking down this issue.
> 
> Peace,
> Gene Steinberg
> 

Hello

Does the debug mode give something understandable ?