Those are async progress threads - they block unless something requires doing
> On Apr 15, 2015, at 8:36 AM, Sasso, John (GE Power & Water, Non-GE) > <john1.sa...@ge.com> wrote: > > I stumbled upon something while using ‘ps –eFL’ to view threads of processes, > and Google searches have failed to answer my question. This question holds > for OpenMPI 1.6.x and even OpenMPI 1.4.x. > > For a program which is pure MPI (built and run using OpenMPI) and does not > implement Pthreads or OpenMP, why is it that each MPI task appears as having > 3 threads: > > UID PID PPID LWP C NLWP SZ RSS PSR STIME TTY TIME CMD > sasso 20512 20493 20512 99 3 187849 582420 14 11:01 ? 00:26:37 > /home/sasso/mpi_example.exe > sasso 20512 20493 20588 0 3 187849 582420 11 11:01 ? 00:00:00 > /home/sasso/mpi_example.exe > sasso 20512 20493 20599 0 3 187849 582420 12 11:01 ? 00:00:00 > /home/sasso/mpi_example.exe > > whereas if I compile and run a non-MPI program, ‘ps –eFL’ shows it running as > a single thread? > > Granted the CPU utilization (C) for 2 of the 3 threads is zero, but the > threads are bound to different processors (11,12,14). I am curious as to > why this is, and no complaining that there is a problem. Thanks! > > --john > > _______________________________________________ > users mailing list > us...@open-mpi.org <mailto:us...@open-mpi.org> > Subscription: http://www.open-mpi.org/mailman/listinfo.cgi/users > <http://www.open-mpi.org/mailman/listinfo.cgi/users> > Link to this post: > http://www.open-mpi.org/community/lists/users/2015/04/26739.php > <http://www.open-mpi.org/community/lists/users/2015/04/26739.php>
