[petsc-users] Terminating a process running petsc via petsc4py without mpi_abort

[Lisandro Dalcin]

(1) You can use PETSc.Sys.pushErrorHandler("abort"), but it will not help
you. What you really need is to override PETSc's default signal handling

(2) While it is true that PETSc overrides the signal handler, you can
override it again from python after from petsc4py import PETSc.

For implementing (2), maybe you should try sending SIGINT and not SIGTERM,
such that you can do the following.

from petsc4py import PETSc

import signal
signal.signal(signal.SIGINT, signal.default_int_handler)

...

if __name__ == "__main__":
    try:
        main()
    except KeyboardInterrupt: # Triggered if Ctrl+C or signaled with SIGINT
        ... # do cleanup if needed

Otherwise, you just need  signal.signal(signal.SIGINT, signal.SIG_DFL)


PS: I'm not in favor of changing current PETSc's signal handling behavior.
This particular issue is fixable with two lines of Python code:

from signal import signal, SIGINT, SIG_DFL
signal(SIGINT, SIG_DFL)



On Thu, 4 Jun 2020 at 23:39, Hudson, Stephen Tobias P <shudson at anl.gov>
wrote:

> Lisandro,
>
> I don't see an interface to set this through petsc4py. Is it possible?
>
> Thanks,
> Steve
> ------------------------------
> *From:* Hudson, Stephen Tobias P <shudson at anl.gov>
> *Sent:* Thursday, June 4, 2020 2:47 PM
> *To:* Balay, Satish <balay at mcs.anl.gov>
> *Cc:* petsc-users at mcs.anl.gov <petsc-users at mcs.anl.gov>; Lisandro Dalcin <
> dalcinl at gmail.com>
> *Subject:* Re: Terminating a process running petsc via petsc4py without
> mpi_abort
>
> Sounds good. I will have a look at how to set this through petsc4py.
>
> Thanks
> Steve
> ------------------------------
> *From:* Satish Balay <balay at mcs.anl.gov>
> *Sent:* Thursday, June 4, 2020 2:32 PM
> *To:* Hudson, Stephen Tobias P <shudson at anl.gov>
> *Cc:* petsc-users at mcs.anl.gov <petsc-users at mcs.anl.gov>; Lisandro Dalcin <
> dalcinl at gmail.com>
> *Subject:* Re: Terminating a process running petsc via petsc4py without
> mpi_abort
>
> I don't completely understand the issue here. How is sequential run
> different than parallel run?
>
> In both cases - a PetscErrorHandler is likely getting invoked. One can
> change this behavior with:
>
>
> https://www.mcs.anl.gov/petsc/petsc-current/docs/manualpages/Sys/PetscPushErrorHandler.html
>
> And there are a few default error handlers to choose
>
>
> PETSC_EXTERN PetscErrorCode PetscTraceBackErrorHandler(MPI_Comm,int,const
> char*,const char*,PetscErrorCode,PetscErrorType,const char*,void*);
> PETSC_EXTERN PetscErrorCode PetscIgnoreErrorHandler(MPI_Comm,int,const
> char*,const char*,PetscErrorCode,PetscErrorType,const char*,void*);
> PETSC_EXTERN PetscErrorCode
> PetscEmacsClientErrorHandler(MPI_Comm,int,const char*,const
> char*,PetscErrorCode,PetscErrorType,const char*,void*);
> PETSC_EXTERN PetscErrorCode PetscMPIAbortErrorHandler(MPI_Comm,int,const
> char*,const char*,PetscErrorCode,PetscErrorType,const char*,void*);
> PETSC_EXTERN PetscErrorCode PetscAbortErrorHandler(MPI_Comm,int,const
> char*,const char*,PetscErrorCode,PetscErrorType,const char*,void*);
> PETSC_EXTERN PetscErrorCode
> PetscAttachDebuggerErrorHandler(MPI_Comm,int,const char*,const
> char*,PetscErrorCode,PetscErrorType,const char*,void*);
> PETSC_EXTERN PetscErrorCode PetscReturnErrorHandler(MPI_Comm,int,const
> char*,const char*,PetscErrorCode,PetscErrorType,const char*,void*);
>
> Some of the are accessible via command line option. for ex:
> -on_error_abort or -on_error_mpiabort
>
> Or perhaps you want to completely disable error handler with:
> -no_signal_handler
>
> cc: petsc-users
>
> Satish
>
> On Thu, 4 Jun 2020, Hudson, Stephen Tobias P wrote:
>
> > Satish,
> >
> > We are having issues caused by MPI_abort getting called when we try to
> terminate a sub-process running petsc4py. Ideally we would always use a
> serial build of petsc/petsc4py in this mode, but many users will have a
> parallel build. We need to be able to send a terminate signal that just
> kills the process.
> >
> > Is there a way to turn off the mpi_abort?
> >
> > Thanks,
> >
> > Steve
> >
> >
>
>

-- 
Lisandro Dalcin
============
Research Scientist
Extreme Computing Research Center (ECRC)
King Abdullah University of Science and Technology (KAUST)
http://ecrc.kaust.edu.sa/
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.mcs.anl.gov/pipermail/petsc-users/attachments/20200605/dee226d5/attachment.html>