Watchdog fails to catch file modification while the file is opened by another program

Question

I'm trying to use watchdog to monitor a specific log file of a program. However, on_modified is called only when that program initiates and closes, even though the log file is being modified in real time. I believe that this is because the log file is being used by the program. If I make another text file in that directory, open it up, write something in it, and save it, the on_modified is called when I save it. If I try to delete that file while it is opened in notepad, the file will be deleted successfully. However, for the log file, I get a file in use error. I believe this might be the reason watchdog can't capture the moment of its modification. Any suggestions to resolve or bypass this problem?