Re: Hash table GC

[Eli Zaretskii]

> From: Anand Tamariya <atamariya@gmail.com>
> Date: Tue, 15 Oct 2024 13:18:10 +0530
> Cc: emacs-devel@gnu.org
> 
> I'm trying to use a hash table for storing parsed CSS values. I'm seeing a 
> degradation in performance
> (memory and CPU) over a period of time. Trying to investigate how to fix the 
> same. Below is a minimal
> example:
> 
> (dotimes (i 10000)
>   (let* ((a (make-hash-table :test 'equal :weakness 'key-or-value))
> (j 0))
>     (dolist (prop '(padding margin margin-top border
>                             color background background-color display
>                             width height clear
>                             font font-size font-style font-weight))
>       (puthash j (list prop (setq j (1+ j))) a))
>     (pp a)
>     ))

You are using 'key-or-value, which prevents the table from being GCed
of _either_ key or value cannot be GCed.  And your keys are symbols,
so they are not GCed.

So I think you should not use 'key-or-value if you want the table to
be GCed.  E.g., why not use t instead?