FW: [Bug-gnubg] Simple multi-threading... Cache

[Ian Shaw]

Jonathan Kinsey wrote on 22 January 2007 18:57
> 
> After some further testing, I was getting some small differences in 
> the results.  I found the global eval cache needed to be protected to 
> stop multiple accesses (from different threads), but am still getting 
> differences.
> 
> Does anyone know if adding positions to the cache from multiple 
> threads (i.e. further ahead in the game), could cause differences in 
> the final results?
> 
> I may need to have a separate cache for each thread, but this would 
> probably lead to many positions being evaluated more than once?
> 
> I'm not sure exactly how the cache works so any thoughts would be 
> helpful!

Is the context/ply of the evaluation stored in the cache?

If not, an evaluation stored by thread A at 1-ply could be accessed by
thread B at 0 or 2 ply, thus leading to slightly different results.

-- Ian