Alex Rivera | Logout

How to create a thread-safe singleton in python

Asked 2011-06-16T07:09:45.050
13

I would like to hold running threads in my Django application. Since I cannot do so in the model or in the session, I thought of holding them in a singleton. I've been checking this out for a while and haven't really found a good how-to for this.

Does anyone know how to create a thread-safe singleton in python?

EDIT:

More specifically what I wand to do is I want to implement some kind of "anytime algorithm", i.e. when a user presses a button, a response returned and a new computation begins (a new thread). I want this thread to run until the user presses the button again, and then my app will return the best solution it managed to find. to do that, i need to save somewhere the thread object - i thought of storing them in the session, what apparently i cannot do.

The bottom line is - i have a FAT computation i want to do on the server side, in different threads, while the user is using my site.

python django singleton thread-safety
Edit
Report

1 Answer

1

If you want asynchronous code in a web application then you're taking the wrong approach. You should run background tasks with a specialist task queue like Celery: http://celeryproject.org/

The biggest problem you have is web server architecture. Unless you go against the recommended Django web server configuration and use a worker thread MPM, you will have no way to track your thread handles between requests as each request typically occupies its own process. This is how Apache normally works: http://httpd.apache.org/docs/2.0/mod/prefork.html

EDIT:

In light of your edit I think you might learn more by creating a custom solution that does this:

  • Maintains start/stop state in the database
  • Create a new program that runs as a daemon
  • Periodically check the start/stop state and begin or end work from here

There's no need for multithreading here unless you need to create a new process for each user. If so, things get more complicated and using Celery will make your life much easier.

answered 2011-06-16T09:11:55.787

Your Answer