On Wed, 19 May 2010 15:11:37 +0200, Jakob Bohm <[email protected]> wrote: > On 19-05-2010 14:03, Emerson Pinter wrote: >> Hi all. >> >> I'm using Courier IMAP for 6 years in my mail servers. It's very stable. >> Since last year, I'm looking for implementing IMAP IDLE in my email >> system. >> During my tests with 2 or 3 accounts under low load, imap idle worked >> fine. >> So I decided to enable IDLE in my production servers (using libgamin). >> That day was a complete disaster. The server with Courier IMAP+IDLE >> enabled, kept thousands of connections open with no activity until the >> machine froze. >> Once I disabled IDLE, the server returned to normal again. >> >> > Note that IDLE is *supposed* to make the clients keep the connections > open as long as they have their client > programs open (which is all day for many people). So thousands of > zero-traffic open connections just waiting > for either end to have something to say is the normal behavior for any > IMAP/IDLE server. This in turn implies > that any server providing IDLE support will need to sustain a load of at
> least 1.5 (guestimate) connections per > user, most of them doing nothing. This means that your system-wide > limits on open TCP connections, > processes etc. need to be at least that high (OK, some IMAP servers > serve multiple connections per process > to reduce the memory and process table load somewhat). > > As for your other issues I have no idea if libgamin, famd, courier-imap > or another component of your system > uses polling or other such resource-eating methods when just waiting for > a file change that might happen. > > And I don't know if there is a courier-imap 4.7.0 option to turn off the > no-IDLE-because-no-fam alert > > > ------------------------------------------------------------------------------ > > _______________________________________________ > Courier-imap mailing list > [email protected] > Unsubscribe: https://lists.sourceforge.net/lists/listinfo/courier-imap Ok, I know what IMAP IDLE does, and how it works internally ... Before enable IMAP idle I setup the max connections to 5x the normal. The server load average gone to 450.0 with many imap process using a lot of resources. The maillog with a lot of malloc errors. I'm using IMAP idle with dovecot in another server, with no performance issue or high load. I like Courier-IMAP, but If there's no improvement in imap idle code (I think courier-imap shouldn't depend on libgamin of fam), all my new servers will be dovecot. My opinion: the option to disable the alert is required. Regards. -- Emerson Pinter
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