TypeError：对于多处理池，字符串索引必须为整数

Question

I'm trying to figure out how to use multiprocessing, but having an issue with the following code. When running the pool_testing() function I get a TypeError . I tried changing pool = multiprocessing.Pool() to pool = multiprocessing.Pool(processes=n) , but same error. Can anybody please help?

import multiprocessing  

profile = [{u'firstName': u'Karen', u'age': 20},
           {u'firstName': u'Jon', u'age': 25}] 

def testing(profile):
    for i in profile:
        print ("Hey " + str(i["firstName"]) + "!")

def pool_testing():
    pool = multiprocessing.Pool()
    pool.map(testing, profile)

pool_testing()

Traceback:

File "/System/.../multiprocessing/pool.py", line 567, in get
    raise self._value
TypeError: string indices must be integers

Answer 1

pool.map automatically maps each item of the iterable argument to the function, so you don't need to do it manually ( for i in profile ) - profile is already the item your interested in. The relevant line in the function description:

This method chops the iterable into a number of chunks which it submits to the process pool as separate tasks.

So, in your case your testing function would look like:

def testing(profile):
    print "Hey " + str(profile["firstName"]) + "!"