Why is __name__ == "__main__" not working?

How can I serve a (never ending) log file with Tornado?

• Hi, In a certain application i want to give the user the ability to watch the log file as it gets new line as if one would have been typing "tail -f logfile" on the server. so I got that example of `cat file` which when replacing `cat` with `tail -f` simply does not work.  I guess the reason is that 'tail -f' is never closed, therefore callbacks are never triggered. I think what I need is actually composing my own object while I wonder what kind of an object must that one be, saying what interface must such an object implements https://gist.github.com/671069 below is the cat code I was mentioning above #!/usr/bin/env python import os import tornado.httpserver import tornado.ioloop import tornado.web class StreamHandler(tornado.web.RequestHandler):     @tornado.web.asynchronous     def get(self):         #self.set_header("Content-Type", "application/ogg+ogg")         self.ioloop = tornado.ioloop.IOLoop.instance()         self.pipe = os.popen('cat foo.log')         self.ioloop.add_handler(             self.pipe.fileno(),             self.async_callback(self.on_response),             self.ioloop.READ )     def on_response(self,fd,events):         for line in self.pipe:             self.write( line )         self.ioloop.remove_handler(fd)         self.finish() application = tornado.web.Application([     (r"/", StreamHandler), ]) if __name__ == "__main__":     http_server = tornado.httpserver.HTTPServer(application)     http_server.listen(8888)     tornado.ioloop.IOLoop.instance().start()

• Answer:

  You probably could just use Python's internals to read the file you want to serve to the client. Something along the lines: class TailHandler(tornado.web.RequestHandler): def __init__(self, *a, **kw): self.file = open('/path/to/myfile.txt') self.pos = self.file.tell() @tornado.asynchronous def get(self): def _read_file(): # Read some amout of bytes here. You can't read until newline as it # would block line = self.file.read(4096) if not line: self.file.seek(self.pos) else: self.write(line) self.flush() IOLoop.instance().add_timeout(time.time() + 1, _read_file) _read_file() Now I can't guarantee that this works, but you could do something along these lines. Edit: There should also be error checking, proper closing the file etc.