Failed to run example cases using openmp as backend

Errors
10

Using a clean docker container, I did a simple test using this example.

The test result is shown below. Looks fine.

(base) tang@ea1847c729c7:~/mpi4py$ mpirun -n 20 python mpi4.py
Controller @ MPI Rank   0:  Input 3826176844
   Worker at MPI Rank   1: Output 3826176845 is OK (from ea1847c729c7)
   Worker at MPI Rank   2: Output 3826176846 is OK (from ea1847c729c7)
   Worker at MPI Rank   3: Output 3826176847 is OK (from ea1847c729c7)
   Worker at MPI Rank   4: Output 3826176848 is OK (from ea1847c729c7)
   Worker at MPI Rank   5: Output 3826176849 is OK (from ea1847c729c7)
   Worker at MPI Rank   6: Output 3826176850 is OK (from ea1847c729c7)
   Worker at MPI Rank   7: Output 3826176851 is OK (from ea1847c729c7)
   Worker at MPI Rank   8: Output 3826176852 is OK (from ea1847c729c7)
   Worker at MPI Rank   9: Output 3826176853 is OK (from ea1847c729c7)
   Worker at MPI Rank  10: Output 3826176854 is OK (from ea1847c729c7)
   Worker at MPI Rank  11: Output 3826176855 is OK (from ea1847c729c7)
   Worker at MPI Rank  12: Output 3826176856 is OK (from ea1847c729c7)
   Worker at MPI Rank  13: Output 3826176857 is OK (from ea1847c729c7)
   Worker at MPI Rank  14: Output 3826176858 is OK (from ea1847c729c7)
   Worker at MPI Rank  15: Output 3826176859 is OK (from ea1847c729c7)
   Worker at MPI Rank  16: Output 3826176860 is OK (from ea1847c729c7)
   Worker at MPI Rank  17: Output 3826176861 is OK (from ea1847c729c7)
   Worker at MPI Rank  18: Output 3826176862 is OK (from ea1847c729c7)
   Worker at MPI Rank  19: Output 3826176863 is OK (from ea1847c729c7)