Can't get attribute 'abc' on <module '__main__' from 'abc_h.py'>

If you declare the pool prior to declaring the function you are trying to use in parallel it will throw this error. Reverse the order and it will no longer throw this error. Also, there is a bug in your code, you are feeding all of your data_dict to abc, when you want to feed it as a list. So I changed that line too and it returns some results.

import numpy as npimport matplotlib.pyplot as pltimport sysimport multiprocessingnum_processor=4def abc(data):              w=np.dot(data.reshape(25,1),data.reshape(1,25))     return wpool = multiprocessing.Pool(num_processor)data_final=np.array(range(100))n=100error=[]k_list=[50,100,500,1000,2000]for k in k_list:    dict_data={}        for d_set in range(num_processor):        dict_data[d_set]=data_final[int(d_set*n/4):int((d_set+1)*n/4)]        if(d_set==num_processor-1):            dict_data[d_set]=data_final[int(d_set*n/4):]    tasks = dict_data    results_w=[pool.apply_async(abc, [dict_data[t]]) for t in range(num_processor)]    w_f=[]    for result in results_w:        w_s=result.get()        w_f.append(w_s.tolist())    w_f=np.array(w_f)print (w_f)

Hi i got the same problem but i could fix it.you have to put the definitions out of the script, because windows can't find the function.Maybe you put your code in an if __name__ == '__main__': query and add the function out of them.

import numpy as npimport matplotlib.pyplot as pltimport sysimport multiprocessingdef abc(data):          w=np.dot(data.reshape(25,1),data.reshape(1,25)) return wif __name__ == '__main__':    num_processor=4    pool = multiprocessing.Pool(num_processor)    data_final=np.array(range(100))    n=100    error=[]    k_list=[50,100,500,1000,2000]    for k in k_list:        dict_data={}            for d_set in range(num_processor):            dict_data[d_set]=data_final[int(d_set*n/4):int((d_set+1)*n/4)]            if(d_set==num_processor-1):                dict_data[d_set]=data_final[int(d_set*n/4):]    tasks = dict_data    results_w=[pool.apply_async(abc,dict_data[t]) for t in range(num_processor)]    w_f=[]    for result in results_w:        w_s=result.get()        w_f.append(w_s.tolist())    w_f=np.array(w_f)    print (w_f)

I also faced the same issue.Declaring pool after the function solved the issue.pool = multiprocessing.Pool(num_processor)