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Re: SLAPD denial of connections under load

Howard Chu wrote:

Quanah Gibson-Mount wrote:

--On Wednesday, August 11, 2004 8:43 PM -0400 James Courtney <Jcourtney@inphonic.com> wrote:

Our other problem is that under high load from the mail server we see
that Maildrop claims it cannot connect to the LDAP server. They are on
the same system and Maildrop connects to localhost rather than going out
over the network and back. Maildrop's ldap_simple_bind_s is returning 81
(0x51) which is defined as the constant LDAP_SERVER_DOWN. The server has
been up for 24 hours now and is generally responsive though so this is
confusing. Under what conditions would slapd not accept a network
connection? Threads + backlog exceeded?

I suggest you separate the mail server from the LDAP server. The high load on the system from the mail delivery agent may be preventing slapd from responding.

There isn't enough information here to determine a course of action. You need to get more info before making suggestions on how to fix the problem.

My guess is that slapd is out of file descriptors or there are too many outstanding connections. Using a program like lsof may help to determine if that's the case. There is no way that any mail server can generate more queries than slapd can handle when both are running on the same CPU.

My 2c: when slapd is unable to serve an MTA, usually you need to craft your backend's indices. I really don't see a scenario where looking up an indexed key takes longer than handling an email.

Ciao, p.

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