[Python-ideas] easy thread-safety [was: fork]

[Ron Adam]

On 08/18/2015 01:27 PM, Chris Angelico wrote:
>>> There's no way to make module globals thread-local without making the
>>> >>module object itself thread-local, and if you do that, you probably
>>> >>need to make every object it references thread-local too, etc, etc,
>>> >>etc.
>> >
>> >Something wrong with that? Shouldn't matter as long as there is only a
>> >single thread.

> As long as there's only a single thread, there's no difference between
> process-wide and thread-local. Once you start a second thread,
> something needs to know what objects belong where. That's all.

Just a thought...

What if a new name type, co_mutables, is added to functions objects, and 
a new keyword to go with it, "mutable" to be used like "globals" and 
"nonlocals".  And then raise an error on an attempt to bind a mutable 
object to a name not in co_mutables.

Also, don't include co_mutables in functions scopes.  That would require 
mutable objects to be passed as function arguments to be seen.

Then only mutable objects/names explicitly passed to a new thread need 
to be tracked.

It might be possible to turn that on with a compiler directive at the 
top of a module so normal python code would work normally, and thread 
safe python code would be limited.

Would something in this direction simplify the problem?


Cheers,
    Ron