View source for Courier IMAP and FAM

[[Category:Engineering]]
== Courier IMAP and FAM problems ==
If you installed Courier-IMAP and find that it seems to lock up and timeout
client connections after it has been running for a long period of time (depending on load) 
then you might be having a problem with FAM. The following examples are from
a Qmail Rocks installation, but the basic idea should apply to any installation
of Courier.

The problem is that Courier tries to use FAM even if the service is not running.
For example, RedHat Enterprise Server 64-bit does not start FAM by default,
but imapd will still try to open connections -- these connections never close
and the socket descriptors never time-out or get recycled. You run out of
resources and imapd will stop responding. Your email client will give an error
of timeout while connecting. You will see that "netstat -n" will show 
hundreds of lines something like these:
    Active UNIX domain sockets (w/o servers)
    Proto RefCnt Flags       Type       State         I-Node Path
    unix  2      [ ]         STREAM     CONNECTED     11420  @/tmp/fam-vpopmail-
    unix  2      [ ]         STREAM     CONNECTED     11423  @/tmp/fam-vpopmail-
    unix  2      [ ]         STREAM     CONNECTED     11427  @/tmp/fam-vpopmail-

Reinstall Courier-IMAP. Run ./configure as normal, but before you run make edit
    /downloads/qmailrocks/courier-imap-4.0.2/maildir/config.h
comment out "#define HAVE_FAM 1". Now start the make process and
continue the rest of the installation as usual. Unfortunately, the configure
script does not have an option to build without FAM and it does not
detect that the system is not running FAM.

Courier seems to work fine without FAM on a medium load system
(in my case, about 40 users).