python pathos multiprocessing -

i trying use pathos multiprocessing simple function pass array, splits parallel processes , joins @ end.

here code ported on using multiprocessing function, , instead of importing multiprocessing, imported pathos.

import sys import gender_guesser.detector gender import time pathos import multiprocessing multiprocessing   d = gender.detector()  def guess_gender (name):     n = name.title() # make first letter upper case , rest lower case      g = d.get_gender(n) # guess gender     return g  ls = ['john','joe','amamda','derick','peter','ashley','john','joe','amamda','derick','peter','ashley']  t=time.time()  results=[]   def callback(x):     results.append(x)  pool = multiprocessing.pool(processes=multiprocessing.cpu_count()-1, maxtasksperchild=1)  n in ls:     print (n)     pool.apply_async(guess_gender,args=[n],callback=callback)  pool.close() pool.join()  results = pd.concat(results)   print(time.time()-t) 

however, error:

valueerror: no objects concatenate 

i not sure how extract results of output. documentation on pathos thin.

does have ideas or experience?

fyi running python in jupyter notebooks.