[Pkg-openmpi-maintainers] Bug#845594: openmpi-bin: MPI_Comm_spawn fails if blt_tcp_if_include is set to lo

[Thibaut Paumard]

Package: openmpi-bin
Version: 2.0.1-7
Severity: normal

Dear Maintainer,

I attach a minimal example to be compiled with
 mpicc.openmpi -o slave slave.c
 mpicc.openmpi -o master master.c

Note that slave is an MPI executable that can be launched with e.g.
 mpicc.openmpi -np 4 ./slave
while master calls slave through MPI_Comm_spawn and can be invoked with:
 mpicc.openmpi -np 1 ./master

Under both jessie and sid, the two commands above work as long as a
network interface is up.

If network is down, slave still works the same both under jessie and
sid) but to get master to work without network, under jessie I must do:
 mpirun --mca btl_tcp_if_include lo master
(it also works with network up).

Under sid, this last command always fails with an internal error,
whether or not the network is up. On the contrary, running slave with
the option set always succeeds.

This regression cause the failure of the autopkgtests of gyoto:
 https://ci.debian.net/packages/g/gyoto/unstable/amd64/

Kind regards, Thibaut.

-- System Information:
Debian Release: stretch/sid
  APT prefers unstable
  APT policy: (500, 'unstable')
Architecture: amd64 (x86_64)

Kernel: Linux 4.8.0-1-amd64 (SMP w/1 CPU core)
Locale: LANG=fr_FR.UTF-8, LC_CTYPE=fr_FR.UTF-8 (charmap=UTF-8)
Shell: /bin/sh linked to /bin/dash
Init: systemd (via /run/systemd/system)

Versions of packages openmpi-bin depends on:
ii  libc6           2.24-6
ii  libhwloc5       1.11.5-1
ii  libopenmpi2     2.0.1-7
ii  openmpi-common  2.0.1-7

openmpi-bin recommends no packages.

Versions of packages openmpi-bin suggests:
pn  gfortran  <none>

-- no debconf information
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