How can I use logging in a multithreaded Python application?

How can I use logging in a multithreaded Python application?

You can use the logging module in Python to log messages from multiple threads. It's important to configure the logger properly to ensure thread safety.

What configuration do I need for thread safety?

You should use a QueueHandler to send log messages to a queue, and a separate thread to handle the logging from that queue.

Can you show me a code example?

Sure! Here's a simple example:

import logging
import logging.handlers
import threading
import time

def worker(queue):
    for i in range(5):
        queue.put(f'Log message {i} from thread {threading.current_thread().name}')
        time.sleep(1)

def setup_logger():
    logger = logging.getLogger('my_logger')
    logger.setLevel(logging.DEBUG)
    handler = logging.handlers.QueueHandler(queue)
    logger.addHandler(handler)
    return logger

if __name__ == '__main__':
    queue = queue.Queue()
    logger = setup_logger()
    listener = logging.handlers.QueueListener(queue, logging.FileHandler('log.txt'))
    listener.start()
    threads = [threading.Thread(target=worker, args=(queue,)) for _ in range(3)]
    for thread in threads:
        thread.start()
    for thread in threads:
        thread.join()
    listener.stop()

This code sets up a logger that logs messages from multiple threads to a file.

What if I want to log to a database instead of a file?

You can create a custom logging handler that connects to your database and inserts log records directly into it.