This produces no Backtrace. Here's my *Messages*

Debug on Quit enabled globally
executing Scheme code block (set-example1)...
Starting Geiser REPL for racket ...
There is no ElDoc support in this buffer
Starting Geiser REPL for racket ... [2 times]
Racket REPL up and running!
=>
""
Quit

. . . and no *Backtrace* buffer. I used this code:

#+name:set-example1
#+begin_src scheme :session f1 :exports both :tangle yes :cache yes
:results silent
(define A (set 1 2 3 4))
(define B (set 3 4 5 6))
(define C (set 4 5))

(set-union A B)     ; gives (set 1 2 3 4 5 6)
(set-intersect A B) ; gives (set 3 4)
(set-subtract A B)  ; gives (set 1 2)
(set=? A B)         ; gives #f
(subset? C A)       ; gives #f
(subset? C B)       ; gives #t
#+end_src

and upon C-c C-c, Emacs worked for a long time, finally producing a dead,
unresponsive Racket REPL buffer. Again, if I kill the REPL, then try this
code:

#+name:set-example2
#+begin_src scheme :session f1 :exports both :tangle yes :cache yes
:results silent
(define A (set 1 2 3 4))
(define B (set 3 4 5 6))
(define C (set 4 5))

(set-union A B)
(set-intersect A B)
(set-subtract A B)
(set=? A B)
(subset? C A)
(subset? C B)
#+end_src

it works:

Welcome to Racket v6.8.
racket@> A
(set 1 3 2 4)
racket@>

On Wed, Mar 1, 2017 at 8:40 AM, Nicolas Goaziou <mail@nicolasgoaziou.fr>
wrote:

> Hello,
>
> Lawrence Bottorff <borgauf@gmail.com> writes:
>
> > C-c C-c-ing this code
> >
> > #+begin_src scheme
> > (define (foo x)
> >   ;just add one
> >   (+ 1 x)) ; comment
> > #+end_src
> >
> > causes Racket (geiser) to freeze up. Sometimes I see a
>
> Could you use M-x toggle-debug-on-quit, reproduce the freezing, hit C-g
> and paste the backtrace?
>
> Regards,
>
> --
> Nicolas Goaziou
>