topic Re: cron: b queue max run limit in Operating System - HP-UX

cron: b queue max run limit

Ralph Grothe — Wed, 27 Nov 2002 13:56:52 GMT

Hi,

I wonder if the reason for this is a massive performance bottleneck (but PerfView doesn't indicate such for the time of occurance), or there exists a maximum run limit to be set/configured somewhere?

In /var/adm/cron/log there are excessive entries as such (see below), and all cron jobs weren't executed but (as written) rescheduled.
The only rescue was to restart cron :-(

! b queue max run limit reached Tue Nov 26 18:05:06 MET 2002
! rescheduling at job Tue Nov 26 18:05:06 MET 2002
! b queue max run limit reached Tue Nov 26 18:05:34 MET 2002
! rescheduling at job Tue Nov 26 18:05:34 MET 2002

Can someone give me an explanation or a hint?

Regards
Ralph

Re: cron: b queue max run limit

Jean-Louis Phelix — Wed, 27 Nov 2002 13:58:26 GMT

hi,

have a look at /var/adm/cron/queuedefs (man queuedefs) to see how concurrent cron jobs are limited.

Regards.

Re: cron: b queue max run limit

Pete Randall — Wed, 27 Nov 2002 14:00:53 GMT

Ralph,

If you have PHCO_24702 installed, you need to install PHCO_27141 as well. See this thread:
http://forums.itrc.hp.com/cm/QuestionAnswer/1,,0x1cb03a7b3682d611abdb0090277a778c,00.html

Pete

Re: cron: b queue max run limit

James R. Ferguson — Wed, 27 Nov 2002 14:00:57 GMT

Hi Ralph:

See 'man 4 queuedefs'. The system-wide limit for all queues is 100.

Regards!

...JRF...

Re: cron: b queue max run limit

Shannon Petry — Wed, 27 Nov 2002 14:17:37 GMT

Set queuedefs to allow single or 2 jobs only. Also, make sure you install the patch recommended as your system will sit and spin trying to launch at jobs.

Regards,
Shannon

Re: cron: b queue max run limit

Ralph Grothe — Wed, 27 Nov 2002 14:38:46 GMT

Yes,
it seems you all were right in your assumption of too low queuedef values.
As it revealed upon inspection the value for batch jobs was set to only 4 and that for at jobs also.
For cron there wasn't an entry in the file so that I presume the default of 100 (or what is left from 100 when max batch an d at jobs are subtracted) will be taken for cron.
I increased both max jobs No. to 10 for at and batch (hope this will suffice).
Unfortunately I couldn't find something in neither the manpages of cron nor queuedefs on how this new value is conveyed to the running cron daemon.
I hesitate to restart cron through its init script right now (production server).
Will a SIGHUP to cron's PID be of any help?

Re: cron: b queue max run limit

Pete Randall — Wed, 27 Nov 2002 14:42:33 GMT

Ralph,

I certainly don't think it could hurt.

Pete

Re: cron: b queue max run limit

Pete Randall — Wed, 27 Nov 2002 14:59:59 GMT

Actually, Ralph, I tried the SIGHUP to be sure. It didn't have any ill effects - I just don't know if it will make cron re-read it's config. Try it and let me know, then we'll both have learned something.

Pete

Re: cron: b queue max run limit

Ralph Grothe — Wed, 27 Nov 2002 16:05:47 GMT

Pete,

actually, I cannot tell if SIGHUP has any effect on HP-UX's cron.

(usually this signal was only chosen as an informal convention of daemon developers to have them reread their configuration and reinitialize themselves, because as session leaders that are dissociated from the terminal they have no other need for a SIGHUP.
More recent daemons such as Apache's httpd actually prefer SIGUSR[12] to reinitialize I think)

After I sent cron a SIGHUP I couldn't find a confirming entry that it caught it.

I assume cron wil read queuedefs file (or a hashed copy) continously like new entries to crontabs.

Unfortunately the manpage doesn't reveal anything about its behaviour.

Re: cron: b queue max run limit

Pete Randall — Wed, 27 Nov 2002 16:09:02 GMT

Ralph,

I was hoping that, once you'd SIGHUP'ed, you would be able to see a flow of at jobs. Did you check for that patch I mentioned?

Pete