--- Begin Message ---
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Subject: |
Weak tables in 2.2.2 grow indefinitely |
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Date: |
Mon, 25 Sep 2017 10:49:13 +0200 |
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User-agent: |
Gnus/5.13 (Gnus v5.13) Emacs/25.3 (gnu/linux) |
Consider this program:
--8<---------------cut here---------------start------------->8---
(use-modules (ice-9 format))
(define loops 3000000)
(define table
(make-weak-key-hash-table))
(let loop ((i loops))
(unless #f ;(zero? i)
(when (zero? (modulo i 100000))
(format #t "heap-size: ~,2h MiB table: ~s~%"
(/ (assoc-ref (gc-stats) 'heap-size) (expt 2. 20))
table))
(hashq-set! table (cons 1 2) #t)
(loop (1- i))))
--8<---------------cut here---------------end--------------->8---
On 2.0.14, the heap size stays at around 24 MiB, and the table size is
stable at 224,717 buckets (?).
On 2.2.2, the heap grows indefinitely (though logarithmically). It’s
not deterministic though: sometimes the heap size stabilizes in the
140–300 MiB range, and sometimes it keeps growing endlessly even though
the table size reaches a maxium at 7,190,537 entries.
Ludo’.
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--- Begin Message ---
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Subject: |
Re: bug#28590: Weak tables in 2.2.2 grow indefinitely |
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Date: |
Tue, 07 Nov 2017 11:58:58 +0100 |
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User-agent: |
Gnus/5.13 (Gnus v5.13) Emacs/25.3 (gnu/linux) |
address@hidden (Ludovic Courtès) skribis:
> Consider this program:
>
> (use-modules (ice-9 format))
>
> (define loops 3000000)
>
> (define table
> (make-weak-key-hash-table))
>
> (let loop ((i loops))
> (unless #f ;(zero? i)
> (when (zero? (modulo i 100000))
> (format #t "heap-size: ~,2h MiB table: ~s~%"
> (/ (assoc-ref (gc-stats) 'heap-size) (expt 2. 20))
> table))
>
> (hashq-set! table (cons 1 2) #t)
> (loop (1- i))))
>
> On 2.0.14, the heap size stays at around 24 MiB, and the table size is
> stable at 224,717 buckets (?).
>
> On 2.2.2, the heap grows indefinitely (though logarithmically). It’s
> not deterministic though: sometimes the heap size stabilizes in the
> 140–300 MiB range, and sometimes it keeps growing endlessly even though
> the table size reaches a maxium at 7,190,537 entries.
This is fixed with Andy’s rewrite of weak tables to bucket-and-chains as
in 2.0:
https://git.savannah.gnu.org/cgit/guile.git/commit/?h=stable-2.2&id=a053c0510c4a644f9453166b7b385cf30f6d3a21
https://git.savannah.gnu.org/cgit/guile.git/commit/?h=stable-2.2&id=d01addeb1feba830ddd703e27f89576864a063ff
https://git.savannah.gnu.org/cgit/guile.git/commit/?h=stable-2.2&id=dc8dda77e0c937abae42a76ea88c6e7995adbd9a
https://lists.gnu.org/archive/html/guile-devel/2017-10/msg00051.html
\o/
Ludo’.
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