Question regarding thread atomicity

[Paul Rubin]

Jon Ribbens <jon+usenet at unequivocal.co.uk> writes:
> Ah. This violates my definition of "thread-safe" ;-) If it doesn't go
> up by exactly one every time that line is executed, it isn't doing
> what I want it to do. I guess I'll have to go and add a load of manual
> locking :-(

I have to agree, it looks like a pretty bad bug.  The most natural way
I can think of to fix it is to add something like references to the
bytecode interpreter, so that

             7 LOAD_ATTR                2 (bar)
             10 LOAD_CONST               1 (1)
             13 INPLACE_ADD
             14 ROT_TWO
             15 STORE_ATTR               2 (bar)

would become something like

        LOAD_REF    2   (bar)   # load a pointer to bar's location
        LOAD_CONST  1
        INPLACE_ADD_REF

However, apparently there's some implementation reasons to not want to
do it that way.