[gambit-list] Memory issue with threads

vasil vasil.s.d at gmail.com
Sat Aug 29 07:38:29 EDT 2009


Hi!

I'm trying to understand what is happening with memory in next test cases:

1. Making many threads, but not staring them
--------------------------------------------
Gambit v4.5.1

> (gc-report-set! #t)

> (##gc)

*** GC: 1 ms, 1.33M alloc, 2.14M heap, 654K live (30% 635200+34704)
> (define t (do ((i 0 (+ 1 i)) (l '() (cons (make-thread (lambda ()
(void))) l))) ((> i 1000000) l)))
*** GC: 2 ms, 2.82M alloc, 4.77M heap, 2.08M live (44% 2149968+34704)
*** GC: 5 ms, 5.50M alloc, 10.0M heap, 4.76M live (47% 4953664+34704)
*** GC: 16 ms, 10.8M alloc, 20.5M heap, 10.0M live (49% 10459472+34704)
*** GC: 27 ms, 21.3M alloc, 41.5M heap, 20.5M live (49% 21468624+34704)
*** GC: 54 ms, 42.3M alloc, 83.5M heap, 41.5M live (50% 43486848+34704)
*** GC: 97 ms, 84.3M alloc, 168M heap, 83.5M live (50% 87527232+34704)
*** GC: 200 ms, 168M alloc, 336M heap, 168M live (50% 175605712+34704)
*** GC: 392 ms, 336M alloc, 672M heap, 336M live (50% 351765360+34704)
*** GC: 801 ms, 672M alloc, 1.31G heap, 671M live (50% 704080736+34704)
> (##gc)
*** GC: 1417 ms, 1.15G alloc, 2.30G heap, 1.15G live (50% 1232640240+34704)
> (set! t #f)
> (##gc)
*** GC: 943 ms, 1.15G alloc, 2.30G heap, 1.15G live (50% 1232640192+34704)

2. Making many threads, starting them and waiting for termination
-----------------------------------------------------------------
Gambit v4.5.1

> (gc-report-set! #t)

> (##gc)
*** GC: 3 ms, 1.33M alloc, 2.14M heap, 654K live (30% 635200+34704)
> (define t (do ((i 0 (+ 1 i)) (l '() (cons (make-thread (lambda ()
(void))) l))) ((> i 1000000) l)))
*** GC: 4 ms, 2.83M alloc, 4.77M heap, 2.12M live (44% 2187824+34704)
*** GC: 6 ms, 5.47M alloc, 10.0M heap, 4.76M live (47% 4953664+34704)
*** GC: 14 ms, 10.7M alloc, 20.5M heap, 10.0M live (49% 10460704+34704)
*** GC: 26 ms, 21.2M alloc, 41.5M heap, 20.5M live (49% 21468624+34704)
*** GC: 51 ms, 42.2M alloc, 83.5M heap, 41.5M live (50% 43486848+34704)
*** GC: 97 ms, 84.2M alloc, 168M heap, 83.5M live (50% 87527232+34704)
*** GC: 199 ms, 168M alloc, 336M heap, 168M live (50% 175605712+34704)
*** GC: 396 ms, 336M alloc, 672M heap, 336M live (50% 351765360+34704)
*** GC: 814 ms, 672M alloc, 1.31G heap, 671M live (50% 704080736+34704)
> (##gc)

*** GC: 1404 ms, 1.15G alloc, 2.30G heap, 1.15G live (50% 1232640240+34704)
> (for-each (lambda (x) (thread-start! x) (thread-join! x)) t)
> (##gc)
*** GC: 660 ms, 1.55G alloc, 1.16G heap, 596M live (50% 624635824+34704)
> (set! t #f)
> (##gc)
*** GC: 133 ms, 1.55G alloc, 2.14M heap, 654K live (30% 635200+34704)

---------------------------------------------------------------------
The question is:
why GC does not collect unreferenced thread objects in first case and do
collect them in second case?

Vasil




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