Make flush method not shutdown

[rjurney]

I need my messages to flush after each send, but your flush method shuts down. Can you change this?

[kislyuk]

As a quick workaround for flush not doing what you want, you can use use_queues=False when constructing the log handler to make each log message trigger a log delivery API call.

[kislyuk]

I agree in general that the semantics of flush() as specified by https://docs.python.org/3/library/logging.html#logging.Handler.flush mean it should not trigger shutdown by default.

[terencehonles]

@kislyuk do you know if this is still the case? It looks like it's not since flush looks like it just puts a sentinel on the queue and will force the queues to send when they see it but they continue monitoring the queue after that:

watchtower/watchtower/__init__.py

Lines 286 to 297 in 5002639

	def flush(self):
	"""
	Send any queued messages to CloudWatch. This method does nothing if ``use_queues`` is set to False.
	"""
	# fixme: don't add filter if it's already installed
	self.addFilter(_boto_filter)
	if self.shutting_down:
	return
	for q in self.queues.values():
	q.put(self.FLUSH)
	for q in self.queues.values():
	q.join()

and

watchtower/watchtower/__init__.py

Lines 256 to 257 in 5002639

	while msg != self.END:
	cur_batch = [] if msg is None or msg == self.FLUSH else [msg]