How not to call initialize at each request with Tornado
python-3.x, tornado
Solution
It's not contrary to the doc; have a look at the Structure of a Tornado app section. A `RequestHandler` object is created for each request.
If you want code to be executed when the app is started only, subclass the `Application` class and override `__init__`, or just put it in your runserver function.
Problem
I want to set variables when starting my Tornado webserver, so I tried to override `initialize` on my `RequestHandler` class. But apparently, `initialize` is launched each time a request is made, according to the following code and its output: ``` #!/usr/bin/env python3 # -*- coding: UTF-8 -*- import tornado.web class MainHandler(tornado.web.RequestHandler): def initialize(self): print("Launching initialization...") def get(self): print("Get: {}{}".format(self.request.host, self.request.uri)) app = tornado.web.Application([= (r"/.*", MainHandler) ]) def runserver(): import tornado.ioloop app.listen(8080) tornado.ioloop.IOLoop.instance().start() if __name__ == "__main__": runserver() ``` stdout: ``` ~ ➤ ./redirector.py Launching initialization... Get: 127.0.0.1:8080/ Launching initialization... Get: 127.0.0.1:8080/favicon.ico Launching initialization... Get: 127.0.0.1:8080/favicon.ico Launching initialization... Get: 127.0.0.1:8080/ ``` This behavior is the complete contrary to what is written in the doc: Hook for subclass initialization. (Meaning it is called at the end of `__init__`) So, does anybody know how to do what I want to ? Thanks in advance.