Multithreaded dev web server for the Python Bottle web framework

Monday, February 15th, 2016

I’m writing a simple web application in the Bottle framework. I ran into an issue where I had a single long-running request, but needed to make some additional requests from the browser to the server. It turns out that Bottle’s built in development web server is single-threaded, and can’t handle multiple requests at the same time. This is annoying, since I don’t want to have to deploy my application each time I make a change; that’s what’s the built-in development web server is for.

The solution is easy: create a very simple multithreaded WSGI web server and use that to serve the Bottle application.

wsgiserver.py

"""
Simple multithreaded WSGI HTTP server.
"""

from wsgiref.simple_server import make_server, WSGIServer
from SocketServer import ThreadingMixIn

class ThreadingWSGIServer(ThreadingMixIn, WSGIServer):
    daemon_threads = True

class Server:
    def __init__(self, wsgi_app, listen='127.0.0.1', port=8080):
        self.wsgi_app = wsgi_app
        self.listen = listen
        self.port = port
        self.server = make_server(self.listen, self.port, self.wsgi_app,
                                  ThreadingWSGIServer)

    def serve_forever(self):
        self.server.serve_forever()

We then include that in the file where we create our Bottle app:

app.py

import bottle
import wsgiserver

wsgiapp = bottle.default_app()
httpd = wsgiserver.Server(wsgiapp)
httpd.serve_forever()

We now have a Bottle app that can handle multiple concucrrent requests. I’m not sure how well this works with automatic reloading and such, but I think it should be fine.