"timeout” a Request in Tornado.

tornado-timeout.py

import time
import contextlib

from tornado.ioloop import IOLoop
import tornado.web
from tornado import gen

@gen.coroutine
def async_sleep(timeout):
    yield gen.Task(IOLoop.instance().add_timeout, time.time() + timeout)

@contextlib.contextmanager
def auto_timeout(self, timeout=2): # Seconds
    handle = IOLoop.instance().add_timeout(time.time() + timeout, self.timed_out)
    try:
        yield handle
    except Exception as e:
        print("Caught %s" % e)
    finally:
        IOLoop.instance().remove_timeout(handle)
        if not self._timed_out:
            self.finish()
        else:
            raise Exception("Request timed out") # Don't continue on passed this point

class TimeoutableHandler(tornado.web.RequestHandler):
    def initialize(self):
        self._timed_out = False

    def timed_out(self):
        self._timed_out = True
        self.write("Request timed out!\n")
        self.finish()  # Connection to client closes here.
        # You might want to do other clean up here.

class MainHandler(TimeoutableHandler):

    @gen.coroutine
    def get(self):
        with auto_timeout(self): # We'll timeout after 2 seconds spent in this block.
            self.sleeper = async_sleep(5)
            yield self.sleeper
        print("writing")  # get will abort before we reach here if we timed out.
        self.write("hey\n")

    def on_connection_close(self):
        # This isn't the greatest way to cancel a future, since it will not actually
        # stop the work being done asynchronously. You'll need to cancel that some
        # other way. Should be pretty straightforward with a DB connection (close
        # the cursor/connection, maybe?)
        self.sleeper.set_exception(Exception("cancelled"))


application = tornado.web.Application([
    (r"/test", MainHandler),
])
application.listen(8888)
IOLoop.instance().start()