Some demo tests fail with "MPI_Comm_rank called before MPI_INIT"
Issue #1127
new
The demo_waveguide_serial and demo_stokes-iterative_serial tests fail on my system with the following error:
Directory: /tmp/guix-build-fenics-dolfin-2019.1.0.post0.drv-0/build/demo/undocumented/waveguide/cpp
"demo_waveguide_serial" start time: Feb 04 05:47 UTC
Output:
----------------------------------------------------------
*** The MPI_Comm_rank() function was called before MPI_INIT was invoked.
*** This is disallowed by the MPI standard.
*** Your MPI job will now abort.
Both tests call dolfin::info() early on, which ends up calling dolfin::MPI::rank() via Logger::write() before MPI has been initialized.
It seems that https://bitbucket.org/fenics-project/dolfin/commits/9cc87357b87e250aa628047e0becf86e04091ec3 attempted to fix something similar, but was perhaps not thorough enough.
The following patch fixes both tests for me, and brings the behavior of dolfin::MPI::rank() in line with dolfin::MPI::size()
-- a/dolfin/common/MPI.cpp
+++ b/dolfin/common/MPI.cpp
@@ -143,6 +143,7 @@ MPI_Info& dolfin::MPIInfo::operator*()
unsigned int dolfin::MPI::rank(const MPI_Comm comm)
{
#ifdef HAS_MPI
+ SubSystemsManager::init_mpi();
int rank;
MPI_Comm_rank(comm, &rank);
return rank;
diff --git a/dolfin/common/MPI.h b/dolfin/common/MPI.h
index b93f6df30..854114a3f 100644
--- a/dolfin/common/MPI.h
+++ b/dolfin/common/MPI.h
@@ -102,12 +102,13 @@ namespace dolfin
/// communicator
void reset(MPI_Comm comm);
- /// Return process rank for the communicator
+ /// Return process rank for the communicator. This function will
+ /// also initialize MPI if it hasn't already been initialised.
unsigned int rank() const;
/// Return size of the group (number of processes) associated
- /// with the communicator. This function will also intialise MPI
- /// if it hasn't already been intialised.
+ /// with the communicator. This function will also initialise MPI
+ /// if it hasn't already been initialised.
unsigned int size() const;
/// Set a barrier (synchronization point)
