Multiple IMAP connections from new IMAP clients

Gary Mills mills at
Thu Apr 23 20:42:59 EDT 2009

On Thu, Apr 23, 2009 at 02:23:10PM -0500, Nic Bernstein wrote:
> On 04/23/2009 01:57 PM, Gary Mills wrote:
> >We've had a problem recently with the number of imapd processes on our
> >Cyrus front-end increasing steadily until it filled the process table.
> >It seems that some recent IMAP clients will normally open a number of
> >IMAP connections to their server, and will open more based on user
> >activity.  Each of these causes a new imapd process to be spawned on
> >the front-end.  As far as I know, the server treats each connection
> >independantly, even though the client may consider one to be permanent
> >and the others to be transient.
> >
> >What are people doing to protect their Cyrus servers from this
> >increasing number of connections, each of which consumes resources on
> >the server?  This problem is going to get worse as more sophisticated
> >clients become popular.  Is many small front-ends the solution?
> >  
> We've been using imapproxyd to help solve just this kind of problem.  
> Haven't used it with a murder, but expect it could still be useful.

Does it actually combine separate connections from a single client
into one connection to the server?  I don't know how it could do that
without violating the protocol.

-Gary Mills-    -Unix Support-    -U of M Academic Computing and Networking-

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