lisp threading example
Today I wanted to experiment with threads in lisp (sbcl, in particular).
Here is a trivial example of how to access a shared resource (a closure, keeping a list of integers), from a set of
(use-package :sb-thread) ;; number of threads (defparameter *nt* 10) ;; threads (defvar *threads* '()) ;; mutex to use with shared resource accessed by the threads (defvar *a-mutex* (make-mutex :name "acc-lock")) ;; shared closure accessed by the threads (let ((x '())) (defun acc (v) (with-mutex (*a-mutex*) (push v x))) (defun get-acc () x)) ;; print the shared resource (print (get-acc)) ;; wait for all the threads to return (mapcar #'join-thread ;; run the threads (loop :for i :below *nt* ;; bind i to x so it is local to the thread :collect (let ((x i)) (make-thread #'(lambda () ;; body of the thread (sleep (random 2)) (acc x)) :name x)))) ;; print the shared resource (print (get-acc))
It can't get much simpler than that…