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Subject: Re: [OMPI devel] Signals
From: Ralph H Castain (rhc_at_[hidden])
Date: 2008-04-08 13:47:55

I found what Pak said a little confusing as the wait_daemon function doesn't
actually receive a signal itself - it only detects that a proc has exited
and checks to see if that happened due to a signal. If so, it flags that
situation and will order the job aborted.

So if the proc continues alive, the fact that it was hit with SIGUSR2 will
not be detected by ORTE nor will anything happen - however, if the OS uses
SIGUSR2 to terminate the proc, or if the proc terminates when it gets that
signal, we will see that proc terminate due to signal and abort the rest of
the job.

We could change it if that is what people want - it is trivial to insert
code to say "kill everything except if it died due to a certain signal".

<shrug> up to you folks. Current behavior is what you said you wanted a long
time ago - nothing has changed in this regard for several years.

On 4/8/08 11:36 AM, "Pak Lui" <Pak.Lui_at_[hidden]> wrote:

> First, can your user executable create a signal handler to catch the
> SIGUSR2 to not exit? By default on Solaris it is going to exit, unless
> you catch the signal and have the process to do nothing.
> from signal(3HEAD)
> Name Value Default Event
> SIGUSR1 16 Exit User Signal 1
> SIGUSR2 17 Exit User Signal 2
> The other thing is, I suspect orte_plm_rsh_wait_daemon() in the rsh plm
> might cause the processes to exit if the orted (or mpirun if it's on
> HNP) receives a signal like SIGUSR2; it'd work on killing all the user
> processes on that node once it receives a signal.
> I workaround this for gridengine PLM. Once the gridengine_wait_daemon()
> receives a SIGUSR1/SIGUSR2 signal, it just lets the signals to
> acknowledge a signal returns, without declaring the launch_failed which
> would kill off the user processes. The signals would also get passed to
> the user processes, and let them decide what to do with the signals
> themselves.
> SGE needed this so the job kill or job suspension notification to work
> properly since they would send a SIGUSR1/2 to mpirun. I believe this is
> probably what you need in the rsh plm.
> Richard Graham wrote:
>> I am running into a situation where I am trying to deliver a signal to the
>> mpi procs (sigusr2). I deliver this to mpirun, which propagates it to the
>> mpi procs, but then proceeds to kill the children. Is there an easy way
>> that I can get around this ? I am using this mechanism in a situation where
>> I don't have a debugger, and trying to use this to turn on debugging when I
>> hit a hang, so killing the mpi procs is really not what I want to have
>> happen.
>> Thanks,
>> Rich
>> _______________________________________________
>> devel mailing list
>> devel_at_[hidden]