Multiprocessing: writing into a hdf5 file

Question

I am running a parallelized code in Python and I am trying to save some values within each iteration. My code could be simplified/summarized as follows:

# Import necessary libraries

def func(a,b):
    # Generate some data and save it into "vector".
    
    # Create a Hdf5 file and save data in vector.
    with h5py.File('/some_file.hdf5', 'w') as f:

        f.create_dataset('data_set', data=vector)

# Some code

# Parallelize func
if __name__ == '__main__':
    with mp.Pool(2) as p:
        [p.apply_async(func, args=(elem, b)) for elem in big_array]

I am saving the files while parallelizing to save memory, since I will be working with big amounts of data.

However, every time I run the script, no hdf5 file is generated and the data is not saved.

I am pretty new to Parallelization with Python and I do not understand what the problem is.