(use posix srfi-18)

(define (process& cmd . args)
  (thread-start!
   (make-thread
    (lambda ()
      (print "Running " cmd)
      (let-values (((in out pid) (process cmd args)))
        (let loop ()
          (let-values (((pid exit? status) (process-wait pid 'nohang)))
            (if (zero? pid)
                (begin
                  (thread-sleep! 0.01)
                  (loop))
                (and exit? status)))))))))


(let ((s1 (process& "/bin/sleep" "2"))
      (s2 (process& "/bin/sleep" "2")))
  (pp (thread-join! s1))
  (pp (thread-join! s2)))