How do I handle errors in concurrent futures?

How do I handle errors when using concurrent futures in Python?

You can handle errors in concurrent futures by using the as_completed method or by checking the results of the futures.

Can you give me an example of using as_completed for error handling?

Sure! Here's a simple example:

from concurrent.futures import ThreadPoolExecutor, as_completed

def task(n):
    if n == 2:
        raise ValueError('An error occurred!')
    return n * 2

with ThreadPoolExecutor() as executor:
    futures = {executor.submit(task, i): i for i in range(5)}
    for future in as_completed(futures):
        try:
            result = future.result()
            print(f'Result: {result}')
        except Exception as e:
            print(f'Error for task {futures[future]}: {e}')

What happens if I don't handle errors?

If you don't handle errors, the program may crash, and you'll miss important information about what went wrong.