[fpc-pascal] Better random numbers ?

[Vinzent Hoefler]

On Friday 03 March 2006 12:55, Vincent Snijders wrote:
> Jonas Maebe wrote:
> > On 3 mrt 2006, at 13:42, Vinzent Hoefler wrote:
> >>> BTW, I never would have guessed that the random number generator
> >>> would have used threadvars. I would have thought, that on app
> >>> start you would set one randseed and then call random from all
> >>> threads.
> >>
> >> Considering that the state array for the Mersenne Twister is an
> >> unprotected global variable, calling random from different threads
> >> looks like a bad idea to me.
> >>
> >> I mean, it surely gives you sort of random values, but ...
> >
> > That's why its state (and indeed not just randseed) should be 
> > threadvars.
>
> Or use some locking mechanism. That would be slower, but would safe
> some memory.

I'd suggest both. :)

Objectify the whole Mersenne Twister into a single "class", so that each 
thread can have it's own PRNG if necessary and provide a single global, 
but locked instance of it for the System.Random subroutines.


Vinzent.