Unofficial wish list status.(Jul 2008)

[superdan]

Me Here Wrote:

> Walter Bright wrote:
> 
> > Yes, but the onus will be on you (the programmer) to prevent data races and
> > do proper synchronization.   
> 
> In the scenario described, the main thread initialises the array of data. Then,
> non-overlapping slices of that are tioned out to N worker threads. Only one
> thread ever modifies any given segment. When the worker threads are complete,
> the 'results' are left in the original array available in its entirety only to
> the main thread.
> 
> >You have to be very wary of cache effects when
> > writing data in one thread and expecting to see it in another.
> 
> Are you saying that there is some combination of OS and/or hardware L1/L2
> caching that would allow one thread to read a memory location (previously)
> modified by another thread, and see 'old data'?
> 
> Cos if you are, its a deeply serious bug that if its not already very well
> documented by the OS writer or hardware manufacturers, then here's your chance
> to get slashdotted (and diggited and redited etc. all concurrently) as the
> discoveerer of a fatel processor flaw.

google for "relaxed memory consistency model" or "memory barriers". geez.