UCX warn unexpected tag-receive

Question

What can the following be due to / how to debug it? it happens when closing my MPI application

[1612979755.727913] [compute-0-9:21112:0]       tag_match.c:61   UCX  WARN  unexpected tag-receive descriptor 0x2b2bf64cdbc0 was not matched

Answer 1

Assuming the application exited normally, this probably means that some process sent a message (eg calling MPI_Send ) to a destination process that did not post a matching receive before calling MPI_Finalize . See https://github.com/openucx/ucx/issues/6331#issuecomment-778428537