[jadmin] Maximum concurrent users on one jabberd

Dustin Puryear dpuryear at usa.net
Tue Mar 27 09:46:27 CST 2001


Dustin Puryear wrote:
> 
> Thomas Muldowney wrote:
> >
> > Hey all, yeah this is an annoying problem with linux and select.  Select in
> > general is a poor function for high load systems.  The piece that I'm working
> > on is a fix to the MIO layer that allows the backend to be changed to a more
> > powerful system easily.  I'm almost done ripping it apart.  I hope that when
> > I go to drop it in cvs I'll have select, poll, and devpoll available for use.
> >
> > I'll probably put a patch on jdev to get help testing it.
> 
> I am confused how this is a select() issue. Isn't this just a default
> configuration limitation with Linux, and can be changed (painfully) in

You know what, it is a select() issue. I upped the limits and can
successfully open 4096 files. However, select() fails. I then found that
FD_SETSIZE is set to 1024! Not to sound too simple, but can I just
increase this limit without breaking Linux 2.2? Has anyone experimented
with this? Also, I've heard that 2.4 does away with this issue. Is that
true? We may try an install this week to see if 2.4 works better with a
high-load Jabber service.

Regards, Dustin

> 2.2 and (not so painfully) in 2.4? You can easily hit the limit by
> running simple test code:
> 
> #include <stdio.h>
> 
> #include <sys/types.h>
> #include <sys/stat.h>
> #include <fcntl.h>
> 
> int main(void)
> {
>         int i;
>         int is_done;
> 
>         i = 0;
>         is_done = 0;
>         while (!is_done)
>         {
>                 if (open(tmpnam(NULL), O_CREAT) < 0)
>                 {
>                         printf("fail at index %d\n", i);
>                         is_done = 1;
>                 }
>                 else
>                 {
>                         printf("created file %d\n", i);
>                         i++;
>                 }
>         }
> 
>         return 0;
> }
> 
> This fails at index 1021 under Linux 2.2 for me. Allowing for stdin,
> stdout, and stderr that is 1024 open files.
> 
> Regards, Dustin
> 
> >
> > --temas
> >
> > On Mon, Mar 26, 2001 at 06:42:41PM +0200, Stefan Praszalowicz wrote:
> > > > 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.
> > > >
> > >
> > >
> > > What does that mean ?
> > > How does the commercial server get around this problem ? I suppose you
> > > have
> > > to split connections in sub-pools wich can be select()ed separately...
> > >
> > > Does the CVS version of jabber do that ?
> > >
> > >
> > > _______________________________________________
> > > jadmin mailing list
> > > jadmin at jabber.org
> > > http://mailman.jabber.org/listinfo/jadmin
> >
> >   ------------------------------------------------------------------------
> >    Part 1.2Type: application/pgp-signature
> 
> --
> Dustin Puryear <dpuryear at usa.net>
> http://members.telocity.com/~dpuryear
> In the beginning the Universe was created.
> This has been widely regarded as a bad move. - Douglas Adams
> 
> _______________________________________________
> jadmin mailing list
> jadmin at jabber.org
> http://mailman.jabber.org/listinfo/jadmin

-- 
Dustin Puryear <dpuryear at usa.net>
http://members.telocity.com/~dpuryear
In the beginning the Universe was created. 
This has been widely regarded as a bad move. - Douglas Adams




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