Setting random state in all hunchentoot threads on ccl

[jshr...@gmail.com]

I'm using ccl and hunchentoot. I discovered that each thread needs to have a new random state, otherwise you get the same random sequence each time through, so now the first thing I do in my thread code is (setf *random-state* (make-random-state t)), but this seems wrong. First off, it's setting the global *random-state* every time a thread starts. Also, there should be a way to do this with some sort of :before method on the hunchentoot thread spinner, so that I don't have to do this at the head of every server. As always, your guidance appreciated!

[Kaz Kylheku]

On 2017-09-23, jshr...@gmail.com <jshr...@gmail.com> wrote:
> I'm using ccl and hunchentoot. I discovered that each thread needs to
> have a new random state, otherwise you get the same random sequence
> each time through, so now the first thing I do in my thread code is
> (setf *random-state* (make-random-state t)), but this seems wrong.
> First off, it's setting the global *random-state* every time a thread
> starts.

The way out of that is of course:

(let ((*random-state* (make-random-state t)))
... rest of thread code...)

> Also, there should be a way to do this with some sort of
> :before method on the hunchentoot thread spinner, so that I don't have
> to do this at the head of every server. As always, your guidance
> appreciated!

Not familiar with that thread spinner, but as a general note, I think
this would have to be an :around method, so you could do, in its body,
something like:

(let ((*random-state* (make-random-state t)))
(call-next-method)) ;; the next method has the thread body.

A :before method will return before the next method is dispatched,
which will unravel any bindings it set up.

[jshr...@gmail.com]

Yes, good points, both! (Actually, I don't know why I didn't think of let binding *random-state*, which in retrospect is totally obvious!)

[Pascal J. Bourguignon]

bt:make-thread has an :initial-bindings keyword,
and there's bt:*default-special-bindings*:

(bt:make-thread (function your-thread-main)
:initial-bindings (acons '*random-state* (make-random-state t)
bt:*default-special-bindings*))

--
__Pascal J. Bourguignon
http://www.informatimago.com

[jshr...@gmail.com]

Thanks, Pascal. I was hoping for something more general, so that I don't have to do this for everyone one of my thread-main fns. I guess I could go into the HT code and just look at what it does.