[jadmin] Maximum concurrent users on one jabberd

Todd Bradley TBradley at jabber.com
Mon Mar 26 09:43:34 CST 2001

Hi, Dave.  We had exactly the same problems on
Jabber.com.  Once we hit around 700 or 750 users
on at a time, .xml files started getting corrupted.
Why did we see it so low instead of at 1024 users?
The going theory is that there were 250 to 300
open sockets for server-to-server and inactive

I had a long chat with Temas, one of the core 
open source developers, and he explained that
Linux itself has a hard limit of 1024 sockets
that can be serviced by the select() function.
Supposedly, Solaris doesn't have this problem.
So, he's working on some new piece of software
that will multiplex socket connections (or some-
thing like that) to get around this problem.

Since we couldn't wait for this new front end
to appear, our solution was to upgrade Jabber.com
to the Jabber Commercial Server which at that
time was just about to be released.


-----Original Message-----
From: dave_parkes at uk.ibm.com
To: Jadmin at jabber.org
Sent: 3/26/01 2:52 AM
Subject: [jadmin] Maximum concurrent users on one jabberd

From: Dave Parkes at IBMGB on 26/03/2001 10:52 AM

To:   Jadmin at jabber.org
Subject:  Maximum concurrent users on one jabberd

     we have hit an apparent limit of 1024 concurrent users on our
jabberd configuration. We are running a linux 2.4 kernel and have
ulimit -n to 8192. Before we increased the ulimit we had a disaster,
jabberd reported a load of file errors and xdb trashed a few user.xml
and it decimated our simple jud global.xml file!  Since we increased the
ulimit we no longer get file errors, we get up to 1025 open file
descriptors for the jabberd process and the process seems to force users
off at that point.
     Is there a hard limit of 1024 concurrent users somewhere? I can't
any likely candidates using grep -r 1024 on the jabberd source.



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