Re: RFC 178 (v2) Lightweight Threads

[Steven W McDougall]

> what if i do $i++ and overflow into the float (or bigint) domain? that
> is enough work that you would need to have a lock around the ++. so then
> all ++ would have implied locks and their baggage. i say no atomic ops
> in perl.

>From RFC 178

    [Atomic] operations typically lock their operands to avoid race
    conditions

    Perl source         C Implementation
    $a = $b             lock(a.mutex);
                        lock(b.mutex);
                        free(a.pData);
                        a.length = b.length;
                        a.pData  = malloc(a.length);
                        memcpy(a.pData, b.pData, a.length);
                        unlock(a.mutex);
                        unlock(b.mutex);
                

> leave the locking to the coder and keep perl clean.

If we don't provide this level of locking internally, then

    async { $a = $b } 

is liable to crash the interpreter.


- SWM