a.py

import threading
import hashlib
import queue
import sys


def main(argv):
    for fname in argv:
        try:
            with open(fname, "rb") as f:
                h = hashlib.sha1()
                q = queue.Queue(maxsize=32)

                def reader():
                    while True:
                        data = f.read(512 * 1024)
                        q.put(data)
                        if not data:
                            break

                def hasher():
                    while True:
                        x = q.get()
                        h.update(x)
                        if not x:
                            break

                job = threading.Thread(target=reader)
                job.daemon = True
                job.start()
                hasher()
                job.join()
                print(f"{h.hexdigest()} *{fname}")
        except Exception as ex:
            print(f"{fname} - {ex}")


if __name__ == "__main__":
    main(sys.argv[1:])