The helpers in the Python standard library for concurrent execution, like threading, multiprocessing, concurrent.futures are lacking for certain use cases like backpressure and flow control.

The library works on Python 3.8+, but an important Python bug (bpo-29988) was fixed in Python 3.10, which makes ctrl-c handling much more reliable.

from pillow import Image

def decode_image(path):
	img = Image.open(path)
	img.load()
	return path, img

with ThreadPool(num_workers=3) as tp:

	for result in tp.map(decode_image, Path(".").rglob("*.jpg"), bufsize=10)
		path, img = result.get()
		img.show()
		label = input("label:")
		print(path, label)