Hello Yun Lu,
You are experiencing this error because using the ‘multiprocessing’ Python module from MATLAB is not a supported workflow, as indicated in the following link: http://www.mathworks.com/help/matlab/matlab_external/limitations-to-python-support.html
However, as a workaround, try setting Python executable as the executable to be used by the ‘multiprocessing’ Python module before invoking Python. To do so, try executing the following commands in the MATLAB command window before your call to ‘multiprocessing’ Python module:
>> [v, exe] = pyversion;
>> py.multiprocessing.spawn.set_executable(exe)
Hope this helps.
Thanks
