Is it okay to spawn a thread from django post save signal?
It's not a direct answer to your question but I found this hint from one of the answers in Is Django post_save signal asynchronous?. My post_save signal handler creates a Celery task.
I don't know where you would have read that signals are executed in threads, because it is not at all true. Django does not do anything with threads, and neither should you: if you want to execute something out of process, use a task queue system like Celery.