> From [EMAIL PROTECTED] Wed Jun 28 12:02:12 2000
> Date: Wed, 28 Jun 2000 13:03:47 -0400
> From: "Damian, G. C. (Gerald)" <[EMAIL PROTECTED]>
> To: [EMAIL PROTECTED]
> Subject: LPRng: :chooser option for load balancing queues
>
> Patrick,
>
> I need a little more explaination on using the chooser option for load
> balancing queues.
>
> Prior to 3.6.18 the check_idle option was used in the sub queues. The
> check idle processes for each sub queue ran util they detected a change
> in status(busy->idle).
>
> Now using the chooser option, the main queue gets a list of all its
> sub queues and checks their status. I've got a chooser script that
> checks
> the Appsocket connections to my Phaser printers. (It essentially checks
> for "idle" on UDP port 9101 and the ability to connect to TCP port 9100.
> I had to do this since for my Tek 360s, connections are refused on 9100
> even though 9101 says idle. This is an old problem reported on prior
> postings.) If both checks are OK, my chooser exits with 0 and writes the
> appropriate subqueue name to STDOUT.
>
> Question #1:
>
> Should the chooser run until it detects a free subqueue like check_idle
> or
> exit with an error if it can't find any available subqueues? (Mine runs
> until it finds a free subqueue.)
If there are jobs in the queue then the lpd server will periodically poll
the printers. Do NOT sit in and endless loop. The metacode that LPRng
is using looks like:
while there are printable jobs in the queue do
retry:
foreach job in the queue do
echo >list
for all queues that are not busy
echo "queue" >>list
endfor
printer=`chooser <list +all the ugly filter options`
case exitcode is
JABORT : stop processing queue
JREMOVE : remove job;
JFAIL : continue;
JSUCC : exit loop with printer and job information
endcase
endfor
if printer and job information then
print job on printer (actually start a process)
else
wait for a process to exit with timeout of 'chooser_interval seconds'
or until a signal or something interesting happens
endif
endwhile
The 'chooser_interval' value determines how often the printers
are polled. Note that this polling is done each time a subserver
queue 'service process' exits or a new job is put into the
queue.
>
> Question #2:
>
> How should I handle the error condition where I can't make a connection
> or
> get status from one remote printer, but another is available? As long as
> at least one subqueue is available jobs will get sent, however, the
> master
> queue will never know there is a problem on one of its subqueues. Should
> I
> JABORT if I find a serious problem on any subqueue?
In the chooser program you may want to disable the queue (lpc disable)
send mail, flash lights, or whatever. How you handle this is up to
you.
>
> --------
> Jerry Damian | Ford Email: [EMAIL PROTECTED]
> Ford Motor Co./RCS Dept. | Internet Email: [EMAIL PROTECTED]
> SRL MD 1074 RM 1116 | ph: (313)32-38347 fax: (313)39-04865
> Dearborn, MI 48121-2053 | my opinions != Ford's opinions or policy
Good Questions!
Patrick Powell Astart Technologies,
[EMAIL PROTECTED] 9475 Chesapeake Drive, Suite D,
Network and System San Diego, CA 92123
Consulting 858-874-6543 FAX 858-279-8424
LPRng - Print Spooler (http://www.astart.com)
-----------------------------------------------------------------------------
If you need help, send email to [EMAIL PROTECTED] (or lprng-requests
or lprng-digest-requests) with the word 'help' in the body. For the impatient,
to subscribe to a list with name LIST, send mail to [EMAIL PROTECTED]
with: | example:
subscribe LIST <mailaddr> | subscribe lprng-digest [EMAIL PROTECTED]
unsubscribe LIST <mailaddr> | unsubscribe lprng [EMAIL PROTECTED]
If you have major problems, send email to [EMAIL PROTECTED] with the word
LPRNGLIST in the SUBJECT line.
-----------------------------------------------------------------------------
