Enabling parallel cores usage in scripting interface

[kiranvad]

Hello,
I am trying to fit data using the from bumps.fitters import fit function and tried the following to enable parallel processing. However, I am not sure if this is actually enabling the running on parallel cores as I do not see any improvement in time or any logging output that indicates the usage of parallel computing.
Here's the sample of code that enables usage of MPIMapper from here and here

mapper = MPIMapper.start_mapper(problem, None, cpus=0)
result = fit(problem, method='dream', mapper=mapper, 
                samples=1e2, init = 'cov',  verbose = True, steps=0
                )

Is there something that I am not doing quite right? Any help is appreciated.

cc @pkienzle