[torquedev] job vs. session
garrick at clusterresources.com
Tue Aug 1 15:02:41 MDT 2006
On Tue, Aug 01, 2006 at 02:49:09PM -0700, Diwaker Gupta alleged:
> Hi all,
> Exactly what is the difference between a job and a session? I couldn't
> find any concrete documentation on them. I'm more interested in an
> implementation oriented definition -- for Linux, it seems like jobs
> are executed within processes, and sessions are denoted by PIDs. So
> are sessions simply the execution containers of jobs? Can there be
> multiple jobs per session or vice-versa?
> My apologies if this is common knowledge.
"session" is a Unix term that binds processes together for the purposes
of signal propogation. It is similar to, but different from, process
See the setsid(2) and setpgid(2) manpages for details.
In pbs_server, only jobs are tracked.
Since pbs_mom has to actually keep track of, and control, individual
processes, a finer-grain control is necessary. The job has top-level
process (the user's shell) that belongs to seperate session. The
resources used by the entire session (the user's shell and all child
processes) are counted.
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