Python multiprocessing calling function from module
<p>I have a <code>my_module</code> module with a <code>my_func()</code> function. When I use this function in the parent process, then everything works well (I get the correct result from this function). But when I call this function from child processes then I get this error:</p>

<pre><code>AttributeError: module 'my_module' has no attribute 'my_func'
</code></pre>

<p>Does anybody know what I did wrong? Here is my template code:</p>

<pre><code>import pandas as pd, gc, sys, multiprocessing as mp, traceback as tb
sys.path.append('c:/my_libs/')
import my_module

def mp_func(df, i):
    df['res'] = df.apply(lambda x: my_module.my_func(x, i))
    return df

def other_function(df):
    # do something
    my_list = [1,2,3] # it can change dynamically based on previous code

    df_res = pd.DataFrame()

    mp_pool = mp.Pool(processes=min(len(my_list), mp.cpu_count()))
    try:
        for i_df in [y.get() for y in [mp_pool.apply_async(mp_func\
            , [df[['my_attr']], i]) for i in my_list]]:

            df_res = df_res.append(i_df)

    except Exception as e:
        print('Something went wrong during multiprocessing:\n', e)
        print('\nFull traceback:\n', tb.format_exc())

    finally:
        mp_pool.close()
        gc.collect()

    df_res.to_csv(&lt;...&gt;)    

if __name__ == '__main__':
    df = pd.read_csv(&lt;...&gt;)
    other_function(df)
</code></pre>

<p>And <code>my_module</code> module looks like this:</p>

<pre><code>def my_func(x, i):
    return x * i
</code></pre>

<p>Again, if I run the NOT multiprocessed version of the same code then everything works well. (I use python 3)</p>

<p>Thank you!</p>