From 24983f11e13b1b960bac8cc9d9b57e12a8e03379 Mon Sep 17 00:00:00 2001
From: Michael Kuron <mkuron@icp.uni-stuttgart.de>
Date: Mon, 3 Aug 2020 18:28:59 +0200
Subject: [PATCH] Work around MPI startup race condition on macOS
If a process started by mpiexec finishes too quickly, sometimes some of the other processes are not started.
It is unclear whether this is an OpenMPI or macOS bug, but appears significantly more often since moving from macOS 10.13 to 10.15. OpenMPI 4.0.1 and 3.0.0 both show the issue on macOS 10.15.
---
src/core/mpi/MPIManager.cpp | 9 +++++++++
1 file changed, 9 insertions(+)
diff --git a/src/core/mpi/MPIManager.cpp b/src/core/mpi/MPIManager.cpp
index 2a2ac2482..a334bc16c 100644
--- a/src/core/mpi/MPIManager.cpp
+++ b/src/core/mpi/MPIManager.cpp
@@ -32,6 +32,9 @@
#include <stdexcept>
#include <string>
#include <vector>
+#ifdef __APPLE__
+#include <thread>
+#endif
namespace walberla
{
@@ -94,6 +97,12 @@ void MPIManager::initializeMPI(int* argc, char*** argv, bool abortOnException)
MPI_Initialized(&mpiAlreadyInitialized);
if (!mpiAlreadyInitialized)
{
+#ifdef __APPLE__
+ /* Work around a race condition on macOS.
+ If a process started by mpiexec finishes too quickly, it sometimes doesn't start all processes.
+ */
+ std::this_thread::sleep_for(std::chrono::milliseconds(1000));
+#endif
MPI_Init(argc, argv);
finalizeOnDestruction_ = true;
}
--
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