using futures.concurrent with a class

Question

I have a main that looks like the following:

import gather_filings_per_filer
import os
from concurrent import futures

def put_last_i(arg):
    with open(os.path.dirname(os.path.abspath(__file__)) + '/last_i.txt','w') as f:
            f.write(arg)

def get_last_i():
    with open(os.path.dirname(os.path.abspath(__file__)) + '/last_i.txt','r') as f:
            data = f.readlines()
        return data[0]

if __name__=='__main__':
    i = int(get_last_i())
    g_f_p_f = gather_filings_per_filer.gather_filings_per()
    jobs=[]


    with futures.ThreadPoolExecutor(max_workers = 3) as executor:
        my_d = dict((executor.submit(g_f_p_f.mt_main),j) for j in range(i,297085))

        for future in futures.as_completed(my_d):
            print future
            print future.exception()

And g_f_p_f.mt_main looks like the following:

class gather_filings_per:
       def mt_main(self, i):
            print "Started:",i
            self.w_m = wrap_mysql.wrap_mysql()
            flag = True
            #do stuff...

Gives me the following result:

<Future at 0x5dc2710 state=finished raised TypeError>
mt_main() takes exactly 2 arguments (1 given)
<Future at 0x5dc25b0 state=finished raised TypeError>
mt_main() takes exactly 2 arguments (1 given)

From my perspective mt_main takes only 1 argument (self should not be required given the typical self behavior).

What seems to be going wrong here that I am missing?

ShadowRanger · Accepted Answer · 2016-01-05T03:43:51.763

You're correct, you only need to provide one additional argument, beyond the implicit self. But you didn't give any. So you're one short. Splitting up the submit to make it visually clear:

my_d = dict(  # Making a dict
            # With key as result object from invoking `mt_main` with no additional arguments
            (executor.submit(g_f_p_f.mt_main),
            # And value j
             j)
            for j in range(i,297085))

Perhaps you meant to pass j as an argument? Assuming it should also be the value, that would be:

# Note second argument to submit, which becomes only non-self argument to mt_main
my_d = dict((executor.submit(g_f_p_f.mt_main, j),j) for j in range(i,297085))

Or to simplify a titch, because having concurrent.futures should mean you can use dict comprehensions (which also separates the submit call from it's value with : for better visual parsing):

my_d = {executor.submit(g_f_p_f.mt_main, j): j for j in range(i, 297085)}

using futures.concurrent with a class

1 Answers1