[cups.general] query about the cups class scheduling algorithm

[Helge Blischke]

Ashley GC wrote:
> 
> Hi cups fans,
> 
> Needless to say, I've checked the documentation and the newsgroups
> with no success, so:
> 
> Why does cups schedule a job sent to a class on a printer which is
> unavailble (e.g. turned off) ?
> 
> ( Versions:
> distro: RedHat 9
> cups version: From RedHat RPM: cups-1.1.17-13.3.0.3
> kernel: From RedHat RPM: kernel-2.4.20-30.9
> )
> 
> As a text, I have created a class with two printers, and leave one
> printer turned off. I send a job, which goes to the first printer, I
> then wait a few minutes, then send another job, which gets sent to the
> second printer. Except it's turned off so it stays in the queue.
> 
> The function that seems to be the cause is FindAvailablePrinter in
> scheduler/classes.c, and it does not seem to take into account the
> current state of the printer being checked, except to see if it's
> (last known?) status is idle.
> 
> Is this functionality considered ok, or is under review?, in which
> case I'd like to suggest:
> - dynamic load balancing of jobs on queues on the same class
> - monitoring of printers (ICMP pings, or better, test-connects to the
>   port that will be used (tcp/631, tcp/515, ...)
> 
The scheduler must have means how to determine if a printer is
available.
Please tell some more on your configuration.

Helge

-- 
H.Blischke at srz-berlin.de
H.Blischke at srz-berlin.com
H.Blischke at acm.org