Track progress of ProcessPoolExecutor with tqdm

tqdm_pool.py

from glob import glob

import multiprocessing
from concurrent.futures import ProcessPoolExecutor

import cv2
from PIL import Image
import imagehash

from tqdm import tqdm

num_cores = multiprocessing.cpu_count()

files = glob("images/*")

def process(img_file):
    try:
        cvimg = cv2.imread(img_file)
        img = Image.fromarray(cvimg)
        phash = str(imagehash.phash(img))
        dhash = str(imagehash.dhash(img))
        whash = str(imagehash.whash(img))
        return img_file, phash, dhash, whash
    except:
        return img_file, None, None, None

with ProcessPoolExecutor(max_workers=num_cores) as pool:
    with tqdm(total=len(files)) as progress:
        futures = []

        for file in files:
            future = pool.submit(process, file)
            future.add_done_callback(lambda p: progress.update())
            futures.append(future)

        results = []
        for future in futures:
            result = future.result()
            results.append(result)

with open('results.txt', 'w') as f_out:
    for img, h1, h2, h3 in results:
        f_out.write(img)
        f_out.write('\t')
        f_out.write(str(h1))
        f_out.write('\t')
        f_out.write(str(h2))
        f_out.write('\t')
        f_out.write(str(h3))
        f_out.write('\n')
    f_out.flush()