[cups.general] MaxClient setting and file descriptor

[Kurt Pfeifle]

Johannes Meixner wrote:
> Hello,
> 
> On Jul 3 05:27 Kurt Pfeifle wrote (shortened):
>> You can have 24000 print clients, where each of them prints 1 one-page job
>> per day. That gives you on avarage 1000 connections for the CUPS server per
>> hour, or 1 every 3.6 seconds (*for* *the* *purpose* *of* *job* *submission* !),
>> right? And yet this may mean no more than 10-30 *concurrent* job submission
>> connections at the peak time (due to the uneven distribution of job submissions
>> over the 24 hour time period).
> 
> Only for the fun:
> You can have 24000 usual print clients and be perfectly happy with
> the defaults or you can have one single SAP system as a client ;-)
> Whenever I hear about performace problems in CUPS, I always find out
> that there is somewhere SAP in use ;-)

I can certainly confirm this...  :-)

> Honestly:
> The reason is that one single SAP system can send zillions of
> print jobs in a very short time.

Yes, they typically create batch print jobs: each one very small
(maybe only 1 page), each one with only 1 copy, but 10s of thousands
of pages. Which means: lots of RIP-ing/rendering load.

> I know almost nothing about SAP but I guess it happens, when SAP
> comes to the conclusion that it is the right time to spit out
> all its carefully stored stuff which needs to be printed.

That's why I asked for snapshots of "lpstat -o" and other figures,
so one could determine possible corners for improvement in the setup.

> Kind Regards
> Johannes Meixner

Cheers,

-- 
Kurt Pfeifle
System & Network Printing Consultant ---- Linux/Unix/Windows/Samba/CUPS
Infotec Deutschland GmbH  .....................  Hedelfinger Strasse 58
A RICOH Company  ...........................  D-70327 Stuttgart/Germany