How to Implement a Timeout Function to Prevent Long-Running Processes?

Timeout Function if it Takes Too Long to Finish

In order to avoid a situation where a specific function takes too long to finish, a timeout mechanism can be implemented. This involves setting an alarm using signal handlers that will raise an exception after a predetermined period of time. This method is particularly useful for UNIX environments.

Here's how to utilize this mechanism:

1. Create a Decorator:

import errno
import os
import signal
import functools

class TimeoutError(Exception):
    pass

def timeout(seconds=10, error_message=os.strerror(errno.ETIME)):
    def decorator(func):
        def _handle_timeout(signum, frame):
            raise TimeoutError(error_message)

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

        return wrapper

    return decorator

2. Apply the Decorator:

from timeout import timeout

# Timeout a long running function with the default expiry of 10 seconds.
@timeout
def long_running_function():
    ...

# Timeout after 5 seconds
@timeout(5)
def another_long_running_function():
    ...

This ensures that any function decorated with @timeout will be interrupted if it exceeds the specified timeout period.

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