Created
February 7, 2022 18:41
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Using signals to terminate a killable thread.
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| import time | |
| import threading | |
| import signal | |
| class Job(threading.Thread): | |
| def __init__(self): | |
| super().__init__() | |
| ''' | |
| The shutdown_flag is a threading.Event object that | |
| indicates whether the thread should be terminated. | |
| ''' | |
| self.shutdown_flag = threading.Event() | |
| def run(self): | |
| print(f'Thread #{self.ident} started') | |
| while not self.shutdown_flag.is_set(): | |
| time.sleep(0.5) | |
| print(f'Thread #{self.ident} stopped') | |
| class ServiceExit(Exception): | |
| """ | |
| Custom exception which is used to trigger the clean exit | |
| """ | |
| pass | |
| def service_shutdown(signum, frame): | |
| print(f'Caught signal {signum}') | |
| raise ServiceExit | |
| def main(): | |
| signal.signal(signal.SIGTERM, service_shutdown) | |
| signal.signal(signal.SIGINT, service_shutdown) | |
| print('Starting main program') | |
| # Start the job threads | |
| try: | |
| j1 = Job() | |
| j2 = Job() | |
| j1.start() | |
| j2.start() | |
| # Keep the main thread running, otherwise signals are ignored. | |
| while True: | |
| time.sleep(0.5) | |
| except ServiceExit: | |
| """ | |
| Terminate the running threads. | |
| Set the shutdown flag on each thread to trigger a clean shutdown of each thread. | |
| """ | |
| j1.shutdown_flag.set() | |
| j2.shutdown_flag.set() | |
| # Wait for threads to close... | |
| j1.join() | |
| j2.join() | |
| print('Exit main program') | |
| if __name__ == "__main__": | |
| main() |
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