[DGD] task rollback and random() bias

[Raymond Jennings]

Heh, looks like you've thought of everything.

On Sat, Jun 6, 2015 at 6:55 AM, Felix A. Croes <felix at dworkin.nl> wrote:

> Raymond Jennings <shentino at gmail.com> wrote:
>
> > In Hydra, if you have a task rescheduled AFTER it has accessed random(),
> > could that bias the RNG if certain values of random() at that spot made
> the
> > task less or more prone to being rescheduled?
>
> The seed of the pseudoramdom sequence will be the same when the task is
> rescheduled.  It will only be updated when the task commits.
>
> Each LPC-running thread has its own independent pseudorandom generator
> seed.  You can expect slightly more random than usual sequences, because
> variance in network timing will create scheduler entropy, affecting which
> thread will be chosen to run which task.
>
> Of course, this is still very far from cryptographically random.  For that,
> /dev/random is needed.
>
> Regards,
> Felix Croes
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