Multiprocessing with Python 2.7 throwing attribute error - python-2.7

Question

from itertools import product
from multiprocessing import Pool
with Pool(4) as pool:
pool.map(lambda x: run_test_function(x, arg2, arg3, arg4), arg1)
I am getting below error after executing above code. There some other code as well which I can't write here. But actual problem is coming from this piece of code only.
Traceback (most recent call last):
File "modProfileChange_test.py", line 347, in <module>
main(sys.argv[1:])
File "modProfileChange_test.py", line 336, in main
test_run_code(arg1, arg2, arg3, arg4, arg5, arg6)
File "modProfileChange_test.py", line 23, in test_run_code
with Pool(4) as pool:
AttributeError: __exit__

Answer 1

In Python 2.7, multiprocessing.Pool is not a context manager and thus it can't be used in a with statement
Solution - create a pool using regular assignment to a variable:
my_pool = Pool(4)
my_pool.map(...)
lambda functions don't work with multiprocessing.Pool, even in Python 3.
Solution - emulate a closure using a solution in the link above:
from functors import partial
def run_test_function(x, fun_arg2, fun_arg3, fun_arg4):
# your code here
...
process_func = partial(run_test_function, fun_arg2=arg2, fun_arg3=arg3, fun_arg4=arg4)
Putting this together:
from multiprocessing import Pool
from functools import partial
def run_test_function(x, fun_arg2, fun_arg3, fun_arg4):
# this is an example
print x, fun_arg2, fun_arg3, fun_arg4
if __name__ == "__main__":
arg1 = 1,2,3,4
arg2 = "hello"
arg3 = "world"
arg4 = "!"
process_func = partial(run_test_function, fun_arg2=arg2, fun_arg3=arg3, fun_arg4=arg4)
my_pool = Pool(4)
my_pool.map(process_func, arg1)
Output:
~/test $ python2.7 so10.py
1 hello world !
2 hello world !
3 hello world !
4 hello world !