Python Decorator: Timeout

The timeout decorator in Python is used to limit the execution time of a function. If the function runs longer than the specified time, it raises a TimeoutException. This is particularly useful in scenarios where you want to ensure a function doesn't hang indefinitely.

import signal

class TimeoutException(Exception): pass

def timeout(seconds): def decorator(func): def handler(signum, frame): raise TimeoutException(f"Function {func.__name__} timed out after {seconds} seconds")

def wrapper(*args, **kwargs): signal.signal(signal.SIGALRM, handler) signal.alarm(seconds) try: result = func(*args, **kwargs) finally: signal.alarm(0) return result

return wrapper return decorator

@timeout(5) def long_running_function(): import time time.sleep(10)

try: long_running_function() except TimeoutException as e: print(e) # Output: Function long_running_function timed out after 5 seconds

Explanation

Signal Handling: The signal module is used to set an alarm signal that triggers after the specified time.
TimeoutException: A custom exception is raised when the function exceeds the allotted time.
Decorator Structure: The timeout decorator wraps the target function and manages the timing logic using signal.

Use Cases

Network Requests: Limit the time spent waiting for network responses.
Long Computations: Prevent computationally expensive functions from running indefinitely.
Resource Management: Ensure functions accessing limited resources do not monopolize them.

Limitations

Platform Dependency: The signal module works only on Unix-based systems. => To avoid that, we can use some public services, ex: Sentry to notify errors
Thread Safety: Not suitable for multithreaded applications, as signals are process-wide.

By incorporating a timeout decorator, you can make your programs more robust and prevent potential hang-ups due to long-running functions.

[Python Decorators] Timeout

Python Decorator: Timeout

Explanation

Use Cases

Limitations

Related

Python Decorators

[TIPS] Python List

[TIPS] Python - Get current path