l...@gnu.org (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))))
I’ve changed it to do:
(hashq-set! table (cons 1 2) (make-vector 10000))
Then if we build Guile with -DGC_DEBUG=1, link it against libgc built
with -DKEEP_BACK_PTRS=1, and run with “GC_BACKTRACES=1”, we see that the
heap is full of those 10,000-element vectors:
0x54ae9030 (../libguile/gc.h:232, sz=80008, NORMAL)
Reference could not be found
0x1bee5030 (../libguile/gc.h:232, sz=80008, NORMAL)
Reference could not be found
0x60491030 (../libguile/gc.h:232, sz=80008, NORMAL)
Reference could not be found
Problem is that “Reference could not be found” corresponds to
GC_UNREFERENCED in <gc_backptr.h>, meaning that there’s no reference
holding this object. Interesting no?
(Though it could also be a bug in the back-pointer code, or pretty much
anything!)
Ludo’.
