[torquedev] pbs_mom -p and rerunnable jobs
knielson at adaptivecomputing.com
Thu Jan 7 16:15:00 MST 2010
I am resurrecting a thread. I have received the following from cray.
On Jul 30, 2009, at 3:38 AM, Glen Beane wrote:
>you do not want -p as the default behavior when you reboot a node.
>pbs_mom could find pids that match its last known jobs and attempt to
>take ownership of them when in fact the pids have no relation to the
>previous jobs. -p should not be in any startup script, except for
>maybe a "restart" option
>-p should only be used in rare cases when you need to (re)start
>pbs_mom on a node already running jobs, _never_ at boot time, which is
>why it is not the default and why it is not in most sites startup
>This is a very good advice. I'd like to add one very serious side
>effect from abusing the -p.
>We are running Torque 2.4.1b1-snap.200905131530 on a very large Cray
>system. After a system wide outage, when everything got started
>afresh, I noticed the jobs that had been active at the time of crash
>all got terminated, even though most of these jobs were marked as
>rerunable. Further investigation indicated since we started pbs_mom
>with "-p", MOM ran the scan_non_child_tasks() to look for lost
>children, did not find them, assumed that they finished, and sent
>obit's to the server. Although the server had requeued the jobs when
>it first started, it purged them in response to the obit's.
>So I totally agree with Glen that -p should not be the default.
>Unfortunately, at least with the version of Torque we use, not only -p
>is the default but also there is no way (that I know of) to get back
>the original default behavior, i.e. don't do anything about previous
>jobs when it starts, leave it to the server to decide whether to purge
>or rerun them. I have tried the "-q" setting, it did not do any better.
>I saw the latest Torque release is 2.4.2. Does the pbs_mom startup act
>the same wrong way?
>In summary, the real issue is that not only -p is the default, but also
>there is now way to get the original default behavior, which allows
>jobs to rerun.
>My posting has been forwarded to the torquedev mailing list, but I've
>not heard from them yet.
So who gets broken if -p is no longer the default. For Cray there is no
work around. Unfortunately there is no !-p option. Maybe this is the
solution. I would prefer pbs_mom not to try and recover jobs unless
explicitly requested in a command line parameter at startup.
What are your thoughts?
More information about the torquedev