I think I know the reason. `c_wchar_p` corresponds to the string pointer `wchar_t *`.It's not a good idea to pass pointers between processes. As quoted from `multiprocessing` docs:

Note Although it is possible to store a pointer in shared memory remember that this will refer to a location in the address space of a specific process. However, the pointer is quite likely to be invalid in the context of a second process and trying to dereference the pointer from the second process may cause a crash.

https://docs.python.org/3.6/library/multiprocessing.html?#module-multiprocessing.sharedctypes