Re: frames vs. weak hash tables and garbage collection

[Joe Wells <jbw@macs.hw.ac.uk>]

Thien-Thi Nguyen <ttn@gnuvola.org> writes:

> () Joe Wells <jbw@macs.hw.ac.uk>
> () Thu, 30 Aug 2007 02:27:32 +0100
>
>    ;; The only reference to the new frame is now the key in the hash
>    ;; table.  Because of the weakness, this key should not keep the
>    ;; frame alive.
>
> there's a lot of stuff going on w/ make-frame.
>
> try replacing `(make-frame)' with:
>
>   (x-create-frame-with-faces)
>
> here, i see that `reproduce-bug' returns nil.
> what do you see?

It doesn't help me to even replace make-frame with x-create-frame (the
primitive used by x-create-frame-with-faces).

Are you able to reproduce the bug at all with the code I originally
sent?

Thien-Thi Nguyen <ttn@gnuvola.org> writes:

> another thing: one gc pass may not be enough.
> i see (reproduce-bug) => nil only at:
>
> (dotimes (i N)
>   (garbage-collect))
>
> where (< 1 N).  my emacs is tweaked, however (ymmv).

Running garbage-collect 10 times makes no difference for me.

Here is the code I am now using to reproduce the bug:

  (defun reproduce-bug ()
    (let ((ht (make-hash-table :weakness 'key)))
      (let* (after-make-frame-functions
             (x
              (x-create-frame nil)
              ;;(x-create-frame-with-faces)
              ;;(make-frame)
              ;;(get-buffer-create "xyzzy")
              ))
        (puthash x t ht)
        (delete-frame x)
        ;;(kill-buffer x)
        )
      ;; The only reference to the new frame is now the key in the hash
      ;; table.  Because of the weakness, this key should not keep the
      ;; frame alive.
      (loop repeat 10 do (garbage-collect))
      ;; The hash table should now be empty.
      (let (l)
        (maphash (lambda (k v) (push (cons k v) l)) ht)
        l)))

With the above definition, I still get (reproduce-bug) returning
((#<dead frame emacs@localhost.localdomain 0xa2ae808> . t)) instead of
nil.

-- 
Joe