[petsc-dev] DMDAGlobalToNatural errors with Ubuntu:latest; gcc 7 & Open MPI 2.1.1

Zhang, Junchao jczhang at mcs.anl.gov
Wed Jul 31 14:17:15 CDT 2019

Hi, Fabian,
I found it is an OpenMPI bug w.r.t self-to-self MPI_Send/Recv using MPI_ANY_SOURCE for message matching. OpenMPI does not put correct value in recv buffer.
I have a workaround jczhang/fix-ubuntu-openmpi-anysource<https://bitbucket.org/petsc/petsc/branch/jczhang/fix-ubuntu-openmpi-anysource>. I tested with your petsc_ex.F90 and $PETSC_DIR/src/dm/examples/tests/ex14.  The majority of valgrind errors disappeared. A few left are in ompi_mpi_init and we can ignore them.
I filed a bug report to OpenMPI https://www.mail-archive.com/users@lists.open-mpi.org//msg33383.html and hope they can fix it in Ubuntu.

--Junchao Zhang

On Tue, Jul 30, 2019 at 9:47 AM Fabian.Jakub via petsc-dev <petsc-dev at mcs.anl.gov<mailto:petsc-dev at mcs.anl.gov>> wrote:
Dear Petsc Team,
Our cluster recently switched to Ubuntu 18.04 which has gcc 7.4 and
(Open MPI) 2.1.1 - with this I ended up with segfault and valgrind
errors in DMDAGlobalToNatural.

This is evident in a minimal fortran example such as the attached
example petsc_ex.F90

with the following error:

==22616== Conditional jump or move depends on uninitialised value(s)
==22616==    at 0x4FA5CDB: PetscTrMallocDefault (mtr.c:185)
==22616==    by 0x4FA4DAC: PetscMallocA (mal.c:413)
==22616==    by 0x5090E94: VecScatterSetUp_SF (vscatsf.c:652)
==22616==    by 0x50A1104: VecScatterSetUp (vscatfce.c:209)
==22616==    by 0x509EE3B: VecScatterCreate (vscreate.c:280)
==22616==    by 0x577B48B: DMDAGlobalToNatural_Create (dagtol.c:108)
==22616==    by 0x577BB6D: DMDAGlobalToNaturalBegin (dagtol.c:155)
==22616==    by 0x5798446: VecView_MPI_DA (gr2.c:720)
==22616==    by 0x51BC7D8: VecView (vector.c:574)
==22616==    by 0x4F4ECA1: PetscObjectView (destroy.c:90)
==22616==    by 0x4F4F05E: PetscObjectViewFromOptions (destroy.c:126)

and consequently wrong results in the natural vec

I was looking at the fortran example if I did forget something but I can
also see the same error, i.e. not being valgrind clean, in pure C - PETSc:

cd $PETSC_DIR/src/dm/examples/tests && make ex14 && mpirun
--allow-run-as-root -np 2 valgrind ./ex14

I then tried various docker/podman linux distributions to make sure that
my setup is clean and to me it seems that this error is confined to the
particular gcc version 7.4 and (Open MPI) 2.1.1 from the ubuntu:latest repo.

I tried other images from dockerhub including

gcc:7.4.0 :: where I could neither install openmpi nor mpich through
apt, however works with --download-openmpi and --download-mpich

ubuntu:rolling(19.04) <-- work

debian:latest & :stable <-- works

ubuntu:latest(18.04) <-- fails in case of openmpi, but works with mpich
or with petsc-configure --download-openmpi or --download-mpich

Is this error with (Open MPI) 2.1.1 a known issue? In the meantime, I
guess I'll go with a custom mpi install but given that ubuntu:latest is
widely spread, do you think there is an easy solution to the error?

I guess you are not eager to delve into this issue with old mpi versions
but in case you find some spare time, maybe you find the root cause
and/or a workaround.

Many thanks,
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