close Warning: Can't synchronize with repository "(default)" ("(default)" is not readable or not a Git repository.). Look in the Trac log for more information.

Opened 18 years ago

Closed 18 years ago

#6 closed defect (fixed)

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

Reported by: Raymond Toy 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 (1)

comment:1 Changed 18 years ago by Raymond Toy

Resolution: → fixed
Status: new → closed

Fixed in snapshot 2006-08.

Note: See TracTickets for help on using tickets.