Multiprocessing in KNIME Python Nodes possible?

Question

I am wondering if it is possible to enable multiprocessing in KNIME Python nodes?

This is not working:

import multiprocessing as mp

from multiprocessing import Pool

def parallelize_dataframe(df, func):
   df_split = np.array_split(df, num_partitions)
   pool = Pool(num_cores)
   df = pd.concat(pool.map(func, df_split))
   pool.close()
   pool.join()
   return df


if __name__ == '__main__':
   # the preprocess function does some stuff of string manipulation, 
   # and could be any other function
   output_table = parallelize_dataframe(input_table, preprocess)