Description
The
queudefs file describes the characteristics of the
queues managed by the clock daemon
cron. Each line in the
file that is not a comment uses the following format to describe a
queue:
q . [njobj] [nicen] [nwaitw]
where the fields are:
- q
- Specifies the name of the queue. Jobs started by at default
to queue a; jobs started by batch default
to queue b, and crontab files
default to queue c. Queue names can be any
single-byte character except a space, tab, newline,
null, or number sign (#).
- njob
- Specifies the maximum number of jobs that can be run in the
queue simultaneously. If more than njob jobs are ready to
run, cron runs the first njob jobs immediately,
and runs the others as current jobs terminate. The default value is
100.
- nice
- Specifies the nice value (see nice) that cron assigns
to all jobs in the queue that are not run by a user ID with appropriate
privileges. The default value is 2.
- nwait
- Specifies the number of seconds that cron is to wait
before it reschedules a job that was deferred because there were more
than njob jobs running in that job's queue, or because more
than 25 jobs were running in all queues. The default value is 60.
Lines beginning with a number sign (#) are comments, and are ignored.
Examples
Here is a sample
queudefs file:
#
# Sample queuedefs file
#
a.5j3n
b.3j1n90w
This file indicates that the a queue, for at jobs,
can have a maximum of five jobs running simultaneously. crontab runs
the jobs with a nice value of 3. Because there is no nwait field
for this queue, if cron cannot run a job because too many
other jobs are running, it waits 60 seconds before trying to run it
again.
This file also states that the b queue,
for batch jobs, can have a maximum of three jobs running
simultaneously. cron runs the jobs with a nice value
of 1. If cron cannot run a job because too many other jobs
are running, it waits 90 seconds before trying to run it again. All
other queues can run up to 100 jobs simultaneously; cron runs
these jobs with a nice value of 2 and, if it cannot run a
job because too many other jobs are running, it waits 60 seconds before
trying to run it again.
Related information
The at, batch, and crontab commands.