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RE: SLAPD denial of connections under load

I will try to collect more information.  Sadly I'm a Java and DB guy by
trade so Linux systems debugging isn't my strongpoint.  I'll look at
lsof and see where it leads me.  I would assume that being out of file
descriptors (for sockets) or hitting some other system limit like
threads or procs would result in kernel errors viewable through dmesg
and that system hasn't written anything new viewable with dmesg in a
VERY long time.  Is there anywhere else I should look to determine if
we're maxing out a system resource?

Thank you very much!


-----Original Message-----
From: Howard Chu [mailto:hyc@symas.com] 
Sent: Wednesday, August 11, 2004 11:33 PM
To: Quanah Gibson-Mount
Cc: James Courtney; Open LDAP Software List (E-mail)
Subject: Re: SLAPD denial of connections under load

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
>> been up for 24 hours now and is generally responsive though so this
>> 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
> 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

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
   -- Howard Chu
   Chief Architect, Symas Corp.       Director, Highland Sun
   http://www.symas.com               http://highlandsun.com/hyc
   Symas: Premier OpenSource Development and Support