Issue with the m2n communication dummy test

Using preCICE
1

Hello everyone, I have correctly configured and installed precice and mpich according to the documentation, and passed all ctests. When trying to run the m2n test case in precice-2.5.0/tools/testing/communication_dummies, I encountered a problem. After running with mpi, an error occurred: “Cannot call MPI_INIT or MPI_INIT_THREAD more than once”. After investigating the code, it was found that MPI_Init_thread() was started in mainA.cpp first, and then utils::Parallel::initializeMPI() was started before the communication subdivision. I would like to know why the code is designed this way, and how to correctly run the virtual solvers of mainA and mainB to implement the m2n communication test. If someone could give me some guidance, I really appreciate it!

System info:

OS: Ubuntu 20.04.6

preCICE version:2.5.0

MPICH version:4.1.2

2023-12-28 18-54-11 的屏幕截图
2023-12-28 18-54-11 的屏幕截图1530×875 182 KB

2023-12-28 18-55-52 的屏幕截图
2023-12-28 18-55-52 的屏幕截图1530×875 174 KB

2

Hi,

You can safely ignore this test case.

The mentioned test in tools/testing/communication_dummies is a test case for debugging m2n-related issues in large rank counts. The implementation of m2n has matured to the extent that this test case hasn’t been used in over 6 years.

3

Thanks for your reply. I would like to use m2n communication, run the fluid-solid coupling simulation in multiple ranks, but I couldn’t find any relevant cases in the Tutorials. I don’t have much experience in the fluid-structure coupling, can you tell me some simple examples so that I can run them using MPI.

4

You can run the fluid participant (OpenFOAM) of the perpendicular flap tutorial in parallel.