_08_locks_context_manager_python-threads.py

'''
Program to demonstrate the locks in python threading
using context manager
 
 with lock:
    

(c) www.xanthium.in

https://www.xanthium.in/creating-threads-sharing-synchronizing-data-using-queue-lock-semaphore-python

'''

import time
import threading


def update_list_A(var_list):       #function to write A's to the List
    print('update_list_A thread called ')
    
    #acquire the lock,other threads are not allowed to access the thread during lock
    
    with lock:
        for _ in range(10):
            var_list.append('A')
            time.sleep(0.10)
    
    #lock is released automatically
    
        
    
def update_list_B(var_list): #function to write B's to the List
    print('update_list_B thread called ')
    
    #acquire the lock,other threads are not allowed to access the thread during lock
    
    with lock:
        for _ in range(10):
            var_list.append('B')
            time.sleep(0.10)
    
    #lock is released automatically


lock = threading.Lock()


shared_list =[] #Shared variable to be modified in threads


t1 = threading.Thread(target = update_list_A, args = (shared_list,))
t2 = threading.Thread(target = update_list_B, args = (shared_list,))


t1.start()
t2.start()


t1.join()
t2.join()

print(f'\n{shared_list}')
print('\nEnd of Main Thread\n')