Simple Event

import time, random, threading

download_event = threading.Event()
data_ready_even = threading.Event()

def downloader_worker():
    print("downloader_worker started")

    time.sleep(random.randint(2,10))

    download_event.set()
    print("download ready!")

def process_worker():
    download_event.wait()

    print("process_download started")

    time.sleep(random.randint(2, 10))

    print("process_download ready!")

downloader_thread = threading.Thread(target=downloader_worker)
process_worker_thread = threading.Thread(target=process_worker)

downloader_thread.start()
process_worker_thread.start()