Ticket #6 (closed defect: fixed)

Opened 8 years ago

Last modified 8 years ago

GCed items in weak hash tables are still accessible (with random junk)

Reported by: rtoy Owned by: somebody
Priority: major Milestone:
Component: Core Version: 19c
Keywords: Cc:

Description

Consider this simple transcript:

* (defvar *ht* (make-hash-table :weak-p t))
*HT*
* (setf (gethash (list 1) *ht*) (list 2))
(2)
* *ht*
#<EQL hash table, 1 entry>
* (prog1 t (make-list 1000000))
T
* (gc :full t)
NIL
* *ht*
#<EQL hash table, 0 entries>
* (maphash #'(lambda (k v) (format t "~S -> ~S~%") k v) *ht*)
(7 . :INSTANCE) -> (#<Function "DEF-STREAM-CLASS SIMPLE-STREAM">)

This is totally bogus. I think the problem is that when GC cleans up the weak entry, it doesn't fill in the entry in the table with the empty value. Instead it remains, and ends up pointing to random objects in memory.

Change History

Changed 8 years ago by rtoy

  • status changed from new to closed
  • resolution set to fixed

Fixed in snapshot 2006-08.

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