cyrus perdtion , connections not dying

Rob Mueller robm at fastmail.fm
Tue Apr 8 19:22:26 EDT 2008


>> Usually we have around 700k simultaneous pop connections  on the real
>> servers now with perdition we have 3000+ connections
>
> Er, I didn't write that. That was Ram, the OP. Different person, different 
> institution, similar issues. We don't offer POP here.

Ah oops, got a bit mixed up there.

> We ran into the same problem, the performance limitation on our front end 
> cluster was (is) the number of processes.

> Unfortunately, the same problem applies. Actually, it's worse. Cyrus 
> processes use more RAM: typically 2.0-3.5 MB per process as opposed to 
> 1.5 - 1.9 MB per process. I've even seen cyrus processes with up to 30MB.

There seems to be some confusion here over if the problem is the size of the 
processes, or the actual number of processes.

In many cases, the size of the process won't be the problem. In all UNIX 
OS's, the size the process is doesn't necessarily correlate very strongly to 
how much memory it's really using because lots of that can be shared between 
many processes (COW forking), or just mmaped files into the process space, 
which might not actually be all in memory at that moment.

What's the actual memory status of your production machine (used/free/etc) 
and the cpu status of your production machine (idle/user/system/iowait)?

Then you can work out what your real bottleneck is first.

Rob



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