gevent

gevent/Event

• Source Code

  import gevent
  from gevent.event import Event
  
  '''
  Illustrates the use of events
  '''
  
  evt = Event()
  
  def setter():
      '''After 10 seconds, wake all threads waiting on the value of evt'''
      print('A: Hey wait for me, I have to do something')
      gevent.sleep(10)
      print("A: Ok, I'm done")
      evt.set()
  
  def waiter():
      '''After 10 seconds the get call will unblock'''
      print("B: I'll wait for you")
      evt.wait()  # blocking
      print("B: It's about time")
  
  def main():
      gevent.joinall([
          gevent.spawn(setter),
          gevent.spawn(waiter),
          gevent.spawn(waiter),
          gevent.spawn(waiter),
          gevent.spawn(waiter),
          gevent.spawn(waiter),
      ])
  
  if __name__ == '__main__':
      main()
  

• Exec

  $ python gevent_envet.py
  A: Hey wait for me, I have to do something
  B: I'll wait for you
  B: I'll wait for you
  B: I'll wait for you
  B: I'll wait for you
  B: I'll wait for you
  # 10 seconds later
  A: Ok, I'm done
  B: It's about time
  B: It's about time
  B: It's about time
  B: It's about time
  B: It's about time
  

gevent + Django

• Javacript: Re Ajax Request in onSuccess/onError
• Django: evt.wait() # blocking
• See https://github.com/gevent/gevent/tree/master/examples/webchat

References

[1] TIMEX@StackOverflow, Does Django have a way to open a HTTP long poll connection?

[2] DeveloperWorks@IBM, Reverse Ajax, Part 1: Introduction to Comet