there is a mistake in shared_memory document <https://docs.python.org/3/library/multiprocessing.shared_memory.html> inn second example I run it under windows and it did not worked so I checked the problem was type of variable it must be dtype=np.int32 convert this existing_shm = shared_memory.SharedMemory(name='psm_21467_46075')>>> # Note that a.shape is (6,) and a.dtype is np.int64 in this example>>> c = np.ndarray((6,), dtype=np.int64, buffer=existing_shm.buf)>>> c to this existing_shm = shared_memory.SharedMemory(name='psm_21467_46075')>>> # Note that a.shape is (6,) and a.dtype is np.int64 in this example>>> c = np.ndarray((6,), dtype=np.int32, buffer=existing_shm.buf)>>> c