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

[Gene Steinberg]

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