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bug#59021: Unbounded heap growth when combining dynamic states & delimit
From: |
Maxim Cournoyer |
Subject: |
bug#59021: Unbounded heap growth when combining dynamic states & delimited continuation |
Date: |
Mon, 07 Nov 2022 11:03:26 -0500 |
User-agent: |
Gnus/5.13 (Gnus v5.13) Emacs/28.1 (gnu/linux) |
Hi Ludovic,
Ludovic Courtès <ludo@gnu.org> writes:
> (This is a followup to <https://github.com/wingo/fibers/issues/65>,
> itself a followup to <https://issues.guix.gnu.org/58631>.)
>
> Consider this code:
>
> ;; https://issues.guix.gnu.org/58631
> ;; https://github.com/wingo/fibers/issues/65
>
> (define loss
> (make-vector 1000000))
>
> (let ((tag (make-prompt-tag "my prompt")))
> (define handler
> (lambda (k i)
> (when (zero? (modulo i 2000000))
> (pk 'heap-size (assoc-ref (gc-stats) 'heap-size)))
>
> (call-with-prompt tag
> (lambda ()
> (k (modulo (+ 1 i) 10000000)))
> handler)))
>
> (call-with-prompt tag
> (let ((state (current-dynamic-state)))
> (lambda ()
> ;; (define (with-dynamic-state state thunk)
> ;; (let ((previous #f))
> ;; (dynamic-wind
> ;; (lambda () (set! previous (set-current-dynamic-state state)))
> ;; thunk
> ;; (lambda () (set-current-dynamic-state previous)))))
> (with-dynamic-state state
> (lambda ()
> (let loop ((i 0))
> (loop (abort-to-prompt tag i)))))))
> handler))
>
> On Guile 3.0.8, this program exhibits seemingly unbounded heap growth.
> Uncommenting the local ‘with-dynamic-state’ definition fixes the
> problem.
I've tested both 3.0.8 from Guix on multiple machines (including Berlin)
and 2.2 from Debian 10, and ran the above snippet; it grows initially
but stabilize quickly and then doesn't budge. I've let it run for more
than an hour.
So there's a problem there (?), but it doesn't seem like an unbound leak
from my experiments. Perhaps the reproducer needs to be tweaked to
mimic better what is happening in Shepherd?
--
Thanks,
Maxim