Hi Dominic

Thanks very much for your prompt reply.

Your response works very well.

I didn’t know there is a distinction between semaphores and fsemaphores.

You have helped me a lot.

Thanks again, Jos

 

 

 

From: Dominik Pantůček
Sent: viernes, 12 de noviembre de 2021 18:59
To: racket-users@googlegroups.com
Subject: Re: [racket-users] future question

 

Hi,

 

you are looking for make-fsempahore[1] and related:

 

===

#lang racket

 

(define sema (make-fsemaphore 1))

 

(define (make-th i)

 

(λ ()

   (let loop ((a 0))

(when (zero? (modulo a #e1e6))

     (fsemaphore-wait sema)

     "do what you have to do without disturbing other futures"

     (fsemaphore-post sema))

    (loop (add1 a)))))

(for ((i (in-range (processor-count)))) (future (make-th i)))

(sleep 10)

(exit)

===

 

The above updated source spins all your cores just fine.

 

 

Cheers,

Dominik

[1]

https://docs.racket-lang.org/reference/futures.html#%28part._.Future_.Semaphores%29

 

 

On 12. 11. 21 18:44, Jacob Jozef wrote:

> #lang racket

>

> (define sema (make-semaphore 1))

>

> (define (make-th i)

>

> (λ ()

>

>    (let loop ((a 0))

>

> #;(when (zero? (modulo a #e1e6))

>

>      (semaphore-wait sema)

>

>      "do what you have to do without disturbing other futures"

>

>      (semaphore-post sema))

>

>     (loop (add1 a)))))

>

> (for ((i (in-range (processor-count)))) (future (make-th i)))

>

> (sleep 10)

>

> (exit)

>

 

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