Re: --mx-kill

Hi George,

george wm turner wrote:
>     As SysAdmins, we're thinking of making --mx-kill 60 the
> default on our mpirun commands to force clean up of orphans
> left behind when user's codes error out.  Is there any
> potential problems that we may be setting ourselves up
> for by doing this?  Any guidance would be appreciated.

With the --mx-kill 60 flag, mpirun.ch_mx will try to kill all remaining 
processes 60 seconds after the first process exits. In most situation, 
all processes part of one MPI job will exit roughly at the same time. 
Unfortunately, it is possible to have an application that do extra work 
in one specific process after the call to MPI_Finalize(). In this case, 
this process will be wrongly killed if the extra work is longer than 60 
seconds.

I have never seen such an application on the field though. In my humble 
opinion, the best way to handle this dilemma would be to use a 
comfortable timeout by default, and be aware that some users may need to 
use a different script to either extend the timeout or disable it.

It's a trade-off between convenience for the majority and compatibility 
for the exception :-)

Patricl
-- 
Patrick Geoffray
Myricom, Inc.
http://www.myri.com