A mistake related to

MPI_Comm_free()

is freeing them in different orders on the involved processes. The MPI standard specifies that

MPI_Comm_free()

must be entered by the processes in the communicator collectively. Some MPIs including Intel® MPI Library deadlock if this rule is broken, whereas others implement

MPI_Comm_free()

as a local call with no communication.

To ensure that this error is detected all the time, Intel® Trace Collector treats

MPI_Comm_free()

just like the other collective operations. There is no special error message for

GLOBAL:COLLECTIVE:COMM_FREE_MISMATCH

, it will be reported as a mismatch between collective calls (

GLOBAL:COLLECTIVE:OPERATION_MISMATCH

) or a deadlock, so

GLOBAL:COLLECTIVE:COMM_FREE_MISMATCH

just refers to the check which enables or disables this test, not a specific error instance.