Python- How to flush the log? (django)

Question

I'm working with Django-nonrel on Google App Engine, which forces me to use logging.debug() instead of print().

The "logging" module is provided by Django, but I'm having a rough time using it instead of print().

For example, if I need to verify the content held in the variable x, I will put
logging.debug('x is: %s' % x). But if the program crashes soon after (without flushing the stream), then it never gets printed.

So for debugging, I need debug() to be flushed before the program exits on error, and this is not happening.

Answer 1

I think this may work for you, assuming you're only using one(or default) handler:

>>> import logging >>> logger = logging.getLogger() >>> logging.debug('wat wat') >>> logger.handlers[0].flush() 

It's kind of frowned upon in the documentation, though.

Application code should not directly instantiate and use instances of Handler. Instead, the Handler class is a base class that defines the interface that all handlers should have and establishes some default behavior that child classes can use (or override). http://docs.python.org/2/howto/logging.html#handler-basic

And it could be a performance drain, but if you're really stuck, this may help with your debugging.

Answer 2

I struggled with a similar problem and here is how I solved it. Instead of using logging module directly to output your logs, initialize your own logger as follows:

import sys import logging   def init_logger():     logger = logging.getLogger()      h = logging.StreamHandler(sys.stdout)     h.flush = sys.stdout.flush     logger.addHandler(h)      return logger 

Then, use it instead of logging in your code:

def f():     logger = init_logger()     logger.debug('...') 

As a result, you won't have problems with flushing logs anymore.