cyrus processes & maxchild

Dan White dwhite at
Thu May 13 00:12:04 EDT 2010

On 12/05/10 20:26 -0700, Maria McKinley wrote:
>Good info, thanks Andy, I will probably up the limits. Still curious 
>about what is suppose to happen when the limit is reached, however. As 
>users, what we notice is that some people that are already logged on, 
>can continue to use email, but no one new can log on. I'm sure not all 
>of the "running" processes at this point are active, so I would expect 
>cyrus to start shutting down sleeping processes, but that doesn't seem 
>to happen. Is it really the mode that cyrus will just stop starting new 
>processes, until someone with root power notices and restarts Cyrus? Is 
>there a way to at least send out a notification this is happening? 
>Usually I am one of the people always logged on, so don't notice until 
>someone else lets me know...

It's been my experience that when you've reached the limit on the number of
imapd processes defined by maxchild, no new connections will be served
until one of the actively served users issues a logout, or a 30 minute
inactivity timeout has been reached, at which point the imapd process will
be freed up for new connections (and possibly destroyed depending on if
it's reached its maximum number of uses).

The length of that session timeout is defined by the 'timeout' imapd.conf,
which defaults to 30 minutes and cannot be lowered below 30 minutes (per
RFC3501 spec).

Dan White

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