Thanks for the opinions.

Sounds more like QT signals are somehow hijacking the mpi functionality. Since qt is still monitoring the process. IF i manually kill mpiexec, the QProcess does send the finished() signal.

mpiexec must monitor how many other things are 'connected' to it and only exit once all of them disconnect. Usually only it's own children are connected. Since the QProcesses maintains a connection, it always thinks it needs to stay alive and therefore never exits. Darn.

I'll look into MPI documentation.