hubert@entropy.UUCP (Steve Hubert) (03/06/86)
I presume that this is a well-known problem, but I have not
seen a fix or an explanation for it myself. When the 4bsd (4.[23])
line printer spooler is printing a job and you lprm the active job
it will hang the printer queue as often as not. Has anyone looked
into what is happening and perhaps come up with a fix or am I doing
something wrong that is causing the problem?
Also, when the system crashes while a job is actively printing the
queue will often be hung after reboot.
Steve Hubert
Dept. of Stat., U. of Wash, Seattle
{decvax,ihnp4,ucbvax!lbl-csam}!uw-beaver!entropy!hubert
hubert%entropy@uw-beaver.arparh@cs.paisley.ac.uk (Robert Hamilton) (03/20/86)
In article <256@entropy.UUCP> hubert@entropy.UUCP writes: >I presume that this is a well-known problem, but I have not >seen a fix or an explanation for it myself. When the 4bsd (4.[23]) >line printer spooler is printing a job and you lprm the active job >it will hang the printer queue as often as not. Has anyone looked >into what is happening and perhaps come up with a fix or am I doing >something wrong that is causing the problem? > >Also, when the system crashes while a job is actively printing the >queue will often be hung after reboot. > I don't know if its the same problem but we had a something similar: After lprm on an active job lpd was restarted with printer {hostname} In our case paisley. I added the alias paisley in /etc/printcap and it seemed to work ok. Thus: lp|paisley|local line printer:\ :lp=/dev/lp:sd=/usr/spool/lpd:lf=/usr/adm/lpd-errs:\ :rf=/usr/ucb/fpr: Hope this is some help! -- UUCP: ...!seismo!mcvax!ukc!paisley!rh DARPA: rh%cs.paisley.ac.uk | Post: Paisley College JANET: rh@uk.ac.paisley.cs | Department of Computing, Phone: +44 41 887 1241 Ext. 219 | High St. Paisley. | Scotland. | PA1 2BE
ables@milano.UUCP (03/25/86)
> After lprm on an active job lpd was restarted with printer {hostname} > In our case paisley. > I added the alias paisley in /etc/printcap and it seemed to work ok. > Thus: > > lp|paisley|local line printer:\ > :lp=/dev/lp:sd=/usr/spool/lpd:lf=/usr/adm/lpd-errs:\ > :rf=/usr/ucb/fpr: Well, this will work, but it doesn't really fix the problem, it just patches the symptom. The problem is in the code for lprm, he tries to restart the printer and uses the variable containing the hostname INSTEAD of the variable containing the printer name. It's pretty obvious when you look through the code. The fix above DOES fix the problem, though, and if you're not into patching code, and if it doesn't cause any other problems, it'll do. The REAL fix, is to /usr/src/usr.lib/lpr/rmjob.c as follows: 92c92 < if (assasinated && !startdaemon(host)) --- > if (assasinated && !startdaemon(printer)) -King ARPA: ables@mcc.arpa UUCP: {ihnp4,seismo,ctvax}!ut-sally!im4u!milano!mcc-pp!ables
thorinn@diku.UUCP (Lars Henrik Mathiesen) (03/26/86)
In article <64@paisley.ac.uk> rh@cs.paisley.ac.uk (Robert Hamilton) writes: >After lprm on an active job lpd was restarted with printer {hostname} >In our case paisley. The obvious fix (if you have source) is to change the call of startdaemon in line 92 in rmjob.c from ...startdaemon(host)... to ...startdaemon(printer)... I don't suppose the developer at Berkeley ever tried removing an active print job when other jobs were in the queue. -- Lars Mathiesen, DIKU, U. of Copenhagen, Denmark ..mcvax!diku!thorinn
hosking@convexs.UUCP (03/31/86)
> /* Written 4:40 pm Mar 24, 1986 by ables@milano.UUCP in net.bugs.4bsd */ > The REAL fix, is to /usr/src/usr.lib/lpr/rmjob.c as follows: > 92c92 > < if (assasinated && !startdaemon(host)) > --- > > if (assasinated && !startdaemon(printer)) > > /* End of text from convexs:net.bugs.4bsd */ One of the people here added an additional fix to this code. There are apparently races possible between starting/killing daemons. Our version of rmjob.c looks like this: /* * Restart the printer daemon if it was killed * but first wait until the daemon is really dead */ if (assasinated) { /* added by ACS, 11/12/85 fixes lprm bug */ int lfd; /* lock file descriptor */ lfd = open(LO, O_WRONLY|O_CREAT, 0644); if (lfd < 0) { printf("cannot create %s", LO); exit(1); } /* when lock succeeds it's ok to restart the daemon */ if (flock(lfd, LOCK_EX) < 0) { printf("rmjob: cannot lock %s", LO); exit(1); } (void)close(lfd); /* implicit unlock */ } if (assasinated && !startdaemon(printer)) fatal("cannot restart printer daemon\n"); exit(0); } I've never really looked at the problem in any detail, but since this change went in, I don't recall ever seeing daemons lost due to lprm... and it happened quite a bit before the change went in. Doug Hosking Convex Computer Corp. Richardson, TX {allegra, ihnp4, uiucdcs}!convex!hosking