id	summary	reporter	owner	description	type	status	priority	milestone	component	version	resolution	keywords	cc	difficulty
866	gc goes crazy with faulty finalizers	megane	felix winkelmann	"{{{
;; It seems like the gc stops working correctly after an exception
;; from a faulty finalizer gets caught (and not crash the whole
;; program).

(define n 2000000000)
(define vector-size 100)

(define (make-objects n gc-msg)
  (let loop [(i 0)]
    (let [(o (make-vector vector-size))]
      (print ""making "" i)
      (set-finalizer! o (lambda (ob) (print gc-msg "" "" i))) 
      (if (< i n)
	  (loop (+ 1 i))))))

(set-finalizer! (make-vector 100) (lambda (ob) (+ i 'a)))
(handle-exceptions
    exn
  (begin
    (print ""Caught an exception"" exn))
  (make-objects n ""gc'ing""))

(print ""done"")

;; Result when compiled: 3 cases

;; Case 1: out of memory, tweak n, vector-size to avoid this
;; ...
;; [panic] out of memory - cannot allocate heap segment - execution terminated

;; Case 2:  100% cpu with no apparent progress

;; Output with -:g
;; ...
;; [GC] 2 finalized item(s) still pending
;; [GC] 2680 finalizer value(s) marked
;; [GC] level  1	gcs(minor)  379	gcs(major)  22
;; [GC] stack	0xbfef7880	0xbff36a00	0xbff37880
;; [GC]  from	0x773d9008	0xb731f744	0xb73d9000	0x3ff4673c
;; [GC]    to	0x09123008	0x09123008	0x49123000 
;; [GC] 0 locatives (from 32)
;; 681
;; [GC] 2 finalized item(s) still pending
;; [GC] 2681 finalizer value(s) marked
;; [GC] level  1	gcs(minor)  0	gcs(major)  23
;; [GC] stack	0xbfef7880	0xbff36a00	0xbff37880
;; [GC]  from	0x09123008	0x490cb1d8	0x49123000	0x3ffa81d0
;; [GC]    to	0x773d9008	0x773d9008	0xb73d9000 
;; [GC] 0 locatives (from 32)
;; <- stuck here with 100% cpu

;; Case 3: 100% at the end
;; making 1
;; making 2
;; ...
;; ...
;; gc'ing 103
;; gc'ing 102
;; gc'ing 101
;; Caught an exception#<condition: (exn type)>
;; done
;; <- stuck here with 100% cpu


}}}"	defect	closed	major	4.9.0	core libraries	4.7.x	fixed