Python map多线程

import os
import PIL

from multiprocessing import Pool
from PIL import Image

SIZE = (75,75)
SAVE_DIRECTORY = 'thumbs'

def get_image_paths(folder):
return (os.path.join(folder, f)
for f in os.listdir(folder)
if 'jpeg' in f)

def create_thumbnail(filename):
im = Image.open(filename)
im.thumbnail(SIZE, Image.ANTIALIAS)
base, fname = os.path.split(filename)
save_path = os.path.join(base, SAVE_DIRECTORY, fname)
im.save(save_path)

if name == 'main':
folder = os.path.abspath(
'11_18_2013_R000_IQM_Big_Sur_Mon__e10d1958e7b766c3e840')
os.mkdir(os.path.join(folder, SAVE_DIRECTORY))

images = get_image_paths(folder)

pool = Pool()
pool.map(creat_thumbnail, images)
pool.close()
pool.join()