How Can I Efficiently Monitor File Changes in Python Without Polling?

Monitoring File Changes Without Polling Using Python

Problem:
You have a log file written by another process that you want to monitor for changes. Whenever a change occurs, you need to read the new data for processing.

Background:
You were considering using the PyWin32 library's win32file.FindNextChangeNotification function, but you are unsure how to configure it to watch a specific file.

Solution: Introducing Watchdog
Instead of polling, a more efficient option is to use the Watchdog library. Here's how:

import watchdog.observers
import watchdog.events

class MyEventHandler(watchdog.events.FileSystemEventHandler):
    def on_modified(self, path, metadata):
        # Read the modified log file and perform necessary processing

# Create a Watchdog observer
observer = watchdog.observers.Observer()

# Add the log file path to be watched
observer.schedule(MyEventHandler(), "path/to/log_file")

# Start observing
observer.start()

# Wait indefinitely for changes
observer.join()

Note:
If you are monitoring a file over a mapped network drive, Windows may not "hear" updates to the file as it does on a local disk. Consider using a different approach in such scenarios.

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