python threading daemon meaning code example

Example 1: python daemon thread

import threading
import time

def func_1():
    while True:
        print(f"[{threading.current_thread().name}] Printing this message every 2 seconds")
        time.sleep(2)

# initiate the thread with daemon set to True
daemon_thread = threading.Thread(target=func_1, name="daemon-thread", daemon=True)
# or
# daemon_thread.daemon = True
# or
# daemon_thread.setDaemon(True)
daemon_thread.start()
# sleep for 10 seconds and end the main thread
time.sleep(4)
# the main thread ends

Example 2: python daemon thread

import threading
import time
 
shared_resource = False # Set the resource to False initially
lock = threading.Lock() # A lock for the shared resource
 
def perform_computation():
    # Thread A will call this function and manipulate the resource
    print(f'Thread {threading.currentThread().name} - performing some computation....')
    shared_resource = True
    print(f'Thread {threading.currentThread().name} - set shared_resource to True!')
    print(f'Thread {threading.currentThread().name} - Finished!')
    time.sleep(1)
 
def monitor_resource():
    # Thread B will monitor the shared resource
    while shared_resource == False:
        time.sleep(1)
    print(f'Daemon Thread {threading.currentThread().name} - Detected shared_resource = False')
    time.sleep(1)
    print(f'Daemon Thread {threading.currentThread().name} - Finished!')
 
 
if __name__ == '__main__':
    a = threading.Thread(target=perform_computation, name='A')
    b = threading.Thread(target=monitor_resource, name='B', daemon=True) # Make thread B as a daemon thread
 
    # Now start both threads
    a.start()
    b.start()