# code11.py

import threading

# This class models a thread that blocks to a file

class MyThread(threading.Thread):

lock = threading.Lock()

def __init__(self, i, file):

super().__init__()

self.i = i

self.file = file

# This method is the one executed when the start() method is called.

def run(self):

# Blocks other threads from entering the next block

MyThread.lock.acquire()

try:

self.file.write('This line was written by thread #{}\n'.format(self.i))

finally:

# Releases the resource

MyThread.lock.release()

if __name__ == '__main__':

n_threads = 15

threads = []

# We create a file to write the output.

with open('out.txt', 'w') as file:

# All writing threads are created at once

for i in range(n_threads):

my_thread = MyThread(i, file)

# The thread is started, which executes the run() method.

my_thread.start()

threads.append(my_thread)