I noticed that mesh.hmax() is a local operation in that every process returns the maximum diameter in its part of the mesh. At least the documentation should be clarified here.
mesh.hmax()
Anyways, is there a way to form the global maximum from within Python?
hmax = MPI.max(mesh.hmax())
In DOLFIN 1.4, this will become
hmax = MPI.max(mesh.mpi_comm(), mesh.hmax())