Multiple IMAP connections from new IMAP clients

Gary Mills mills at
Thu Apr 23 14:57:20 EDT 2009

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?

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

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