MPI+Tensorflow – GPU not detected in MPI process

I want to set up distributed RL. Multiple worker and 1 learner. I have 1 GPU and 1 CPU with multiple cores.

So GPU:0 and CPU:0.

Now if i start the programm normal via python programm.py

It detects the GPU and CPU and lists it once i call tf.config.list_physical_device()

However if i start it as MPI application via:

mpiexec -np 4 python programm.py

Every process just lists CPU:0 and no gpu is detected. How can i make at least one process see the gpu?

I use tf2.7 and mpi4py