Thread local storage in Python

Question

How do I use thread local storage in Python?

Related

• What is “thread local storage” in Python, and why do I need it? - This thread appears to be focused more on when variables are shared.
• Efficient way to determine whether a particular function is on the stack in Python - Alex Martelli gives a nice solution

Answer 1

As noted in the question, Alex Martelli gives a solution here. This function allows us to use a factory function to generate a default value for each thread.

#Code originally posted by Alex Martelli
#Modified to use standard Python variable name conventions
import threading
threadlocal = threading.local()    

def threadlocal_var(varname, factory, *args, **kwargs):
  v = getattr(threadlocal, varname, None)
  if v is None:
    v = factory(*args, **kwargs)
    setattr(threadlocal, varname, v)
  return v

Answer 2

Can also write

import threading
mydata = threading.local()
mydata.x = 1

mydata.x will only exist in the current thread