[Python-Dev] Python Interpreter Thread Safety?

[Evan Jones]

Due to the issue of thread safety in the Python memory allocator, I 
have been wondering about thread safety in the rest of the Python 
interpreter. I understand that the interpreter is not thread safe, but 
I'm not sure that I have seen a discussion of the all areas where this 
is an issue. Here are the areas I know of:

1. The memory allocator.
2. Reference counts.
3. The cyclic garbage collector.
4. Current interpreter state is pointed to by a single shared pointer.
5. Many modules may not be thread safe (?).

Ignoring the issue of #5 for the moment, are there any other areas 
where this is a problem? I'm curious about how much work it would be to 
allow concurrent execution of Python code.

Evan Jones

Note: One of the reasons I am asking is that my memory allocator patch 
is that it changes the current allocator from "sort of" thread safe to 
obviously unsafe. One way to eliminate this issue is to make the 
allocator completely thread safe, but that would require some fairly 
significant changes to avoid a major performance penalty. However, if 
it was one of the components that permitted the interpreter to go 
multi-threaded, then it would be worth it.