[racket] racket and OS threads

Hi,

I'm trying to build a sandbox (in Linux) so that a custodian process creates
a child gracket&OS thread. If the child thread should misbehave, the
custodian process ends it and starts a new child thread.

Below is a simplified version of what I have tried

(define thread:child 0)

(define loop
  (lambda ()
       (set! thread:child (thread (lambda () (system "gracket -f
\""...rlt\""))))
       (sleep 30)
       (kill-thread thread:child)
       (loop)))


But, eventhough the racket process ends as expected, the OS process still
stays alive.

Is there a way to kill the OS process as well?


br, jukka