# ch14/example1.py

import threading
import random
import time

def update():
    global counter

    current_counter = counter # reading in shared resource
    time.sleep(random.randint(0, 1)) # simulating heavy calculations
    counter = current_counter + 1 # updating shared resource

counter = 0

threads = [threading.Thread(target=update) for i in range(20)]

for thread in threads:
    thread.start()
for thread in threads:
    thread.join()

print(f'Final counter: {counter}.')
print('Finished.')