Does python logging flush every log?

by

Yes, it does flush the output at every call. You can see this in the source code for the StreamHandler:

def flush(self):
    """
    Flushes the stream.
    """
    self.acquire()
    try:
        if self.stream and hasattr(self.stream, "flush"):
            self.stream.flush()
    finally:
        self.release()

def emit(self, record):
    """
    Emit a record.

    If a formatter is specified, it is used to format the record.
    The record is then written to the stream with a trailing newline.  If
    exception information is present, it is formatted using
    traceback.print_exception and appended to the stream.  If the stream
    has an 'encoding' attribute, it is used to determine how to do the
    output to the stream.
    """
    try:
        msg = self.format(record)
        stream = self.stream
        stream.write(msg)
        stream.write(self.terminator)
        self.flush()   # <---
    except (KeyboardInterrupt, SystemExit): #pragma: no cover
        raise
    except:
        self.handleError(record)

I wouldn’t really mind about the performance of logging, at least not before profiling and discovering that it is a bottleneck. Anyway you can always create a Handler subclass that doesn’t perform flush at every call to emit(even though you will risk to lose a lot of logs if a bad exception occurs/the interpreter crashes).

More Related Contents:

  1. String formatting: % vs. .format vs. f-string literal
  2. Where is a complete example of logging.config.dictConfig?
  3. How to add a custom loglevel to Python’s logging facility
  4. python exception message capturing
  5. Can Python’s logging format be modified depending on the message log level?
  6. How to configure logging to syslog in Python?
  7. Lazy logger message string evaluation
  8. How do I log from my Python Spark script
  9. How to write custom python logging handler?
  10. python logging to database
  11. Suppress newline in Python logging module
  12. Naming Python loggers
  13. Python logging: use milliseconds in time format
  14. Django Setup Default Logging
  15. How to use logging.getLogger(__name__) in multiple modules
  16. Run subprocess and print output to logging
  17. No handlers could be found for logger
  18. How to use Python’s RotatingFileHandler
  19. redirect prints to log file
  20. Set logging levels
  21. How to change filehandle with Python logging on the fly with different classes and imports
  22. Can structured logging be done with Pythons standard library?
  23. Python Logging – Disable logging from imported modules
  24. Redirect Python ‘print’ output to Logger
  25. Link ATLAS/MKL to an installed Numpy
  26. Fastest way to grow a numpy numeric array
  27. What is the fastest way to parse large XML docs in Python?
  28. How to easily print ascii-art text? [closed]
  29. Python built-in sum function vs. for loop performance
  30. Are NumPy’s math functions faster than Python’s?

Leave a Comment