Expose Shutdown Timeout as Configurable Parameter

[theonewolf]

Currently, when waitress receives a SIGINT or traps a SystemExit exception, it tries to shutdown the running task dispatcher.

The shutdown method embeds inside its function signature a hardcoded timeout value of 5 seconds.

This should not be hidden nor hardcoded. It should be exposed as a parameter to the operator.

The line of source code I'm talking about is here:

waitress/waitress/task.py

Line 118 in 68a38e9

def shutdown(self, cancel_pending=True, timeout=5):

and the only place it's called (I believe, outside of tests):

waitress/waitress/server.py

Line 127 in 68a38e9

self.task_dispatcher.shutdown()

[digitalresistor]

Related:

#48
#56

[digitalresistor]

See issue comment here: #269 (comment)

The code referenced above wouldn't help solve for shutdown being configurable in terms of the timeout, in fact, because we never call into asyncore.loop we are no longer sending data to the network. This needs much bigger fixes.