[mpich-discuss] Hydra SIGTSTP (Ctrl+Z) handling

[Pavan Balaji]

On 11/29/2010 06:15 PM, Yauheni Zelenko wrote:
> Hydra have inconsistency in SIGTSTP handling (Ctrl-Z). It's works
> when processes started on same host as mpiexec and not working when
> mpiexec start processes remotely.

Not all signals are supported by Hydra. SIGTSTP is one of the 
unsupported signals. The reason you are seeing inconsistent behavior is 
because the signal handling depends on the launcher. When you launch 
locally, the "fork" launcher is used, and when you launch remotely, the 
"ssh" launcher is used. SSH goes all crazy when it sees an SIGTSTP and 
that is outside Hydra's control (it cannot stop other processes from 
calling a signal handler).

If you are looking to checkpoint the running MPI application, you 
should: (1) configure MPICH2 with checkpointing support, and (2) send 
the SIGUSR1 signal to mpiexec (or give the -ckpoint-interval option to 
mpiexec).

  -- Pavan

-- 
Pavan Balaji
http://www.mcs.anl.gov/~balaji