Parallel processing using multiprocessing and multithreading

image_resizer.py

import concurrent.futures
from PIL import Image
from resizeimage import resizeimage
from os import listdir, getpid
from os.path import isfile, join

SOURCE_DIR = '/var/tmp/source/'
TARGET_DIR = '/var/tmp/target/'
MAX_PROCESSES = 4
MAX_THREADS = 2


class ImageResizer(object):

    def __init__(self):
        self.sizes = [[100, 100], [200, 200], [300, 300], [400, 400], [500, 500], [600, 600], [700, 700], [800, 800], [900, 900], [1000, 1000]]

    def execute(self):
        images = self.get_images()
        self.execute_process(images)

    @staticmethod
    def get_images():
        return [file for file in listdir(SOURCE_DIR) if isfile(join(SOURCE_DIR, file))]

    def execute_process(self, images: list):
        with concurrent.futures.ProcessPoolExecutor(max_workers=MAX_PROCESSES) as process_executor:
            process_futures = process_executor.map(self.resize_image, [(image) for image in images])

            for processed_images in process_futures:
                print("Resized images: {}".format(", ".join(image for image in processed_images)))

    def resize_image(self, image: str):
        pid = getpid()
        print("Running task from process {}".format(pid))

        with concurrent.futures.ThreadPoolExecutor(max_workers=MAX_THREADS) as thread_executor:
            resized_images = []
            thread_futures = thread_executor.map(self.resize, [(image, size) for size in self.sizes])

            for resized_image in thread_futures:
                resized_images.append(resized_image)

        return resized_images

    @staticmethod
    def resize(args):
        file, size = args

        with Image.open(SOURCE_DIR + file) as image:
            cover = resizeimage.resize_cover(image, size)
            resized_image = TARGET_DIR + '-'.join(str(s) for s in size) + file
            cover.save(resized_image, image.format)

        return resized_image

if __name__ == "__main__":
    image_resizer = ImageResizer()
    image_resizer.execute()