An error related to the MPI communicators

[maniset]

Hello,

Thanks for this great library.

I have a question. I have created a solver with shenfun in a function which is used in another code in an iterative process. However, it only works with a limited number of iterations, and if the number of iterations goes up, the shenfun gives the following error.

mpi4py/MPI/Comm.pyx in mpi4py.MPI.Cartcomm.Sub()

Exception: Other MPI error, error stack:
PMPI_Cart_sub(213)..................: MPI_Cart_sub(comm=0x84000000, remain_dims=0x7f1aedab1320, comm_new=0x7f1aed8c7da0) failed
PMPI_Cart_sub(152)..................: 
MPIR_Comm_split_impl(253)...........: 
MPIR_Get_contextid_sparse_group(602): Too many communicators (0/2048 free on this process; ignore_id=0)

I think I should do something like unload the MPI or free the MPI communicators after each iteration (each time solver is used). Is there any way to solve this problem?

Sincerely

[Mikael Mortensen]

Hi,

You are right. If you create a TensorProductSpace in an iterative process, then you need to be careful with garbage control. This is probably not well documented, but the class has a destroy method, that you can call at the end of the iteration, and that should take care of cleaning up. This method is part of mpi4py-fft, see here. It is used for example in the tests here.

[maniset]

Thanks a lot. That works.