Re: [Chicken-users] Re: on the hardship of upgrading chicken from 4.6.1 to 4.6.3 -- what I forgot

[Felix]

From: Jörg "F. Wittenberger" <address@hidden>
Subject: [Chicken-users] Re: on the hardship of upgrading chicken from 4.6.1 to 
4.6.3 -- what I forgot
Date: Wed, 17 Nov 2010 22:35:49 +0100

> Am Mittwoch, den 17.11.2010, 21:59 +0100 schrieb Jörg F. Wittenberger:
>> == Summary ==
>> 
>> That's hard.
>> 
>> ;-) WHY ;-)
> 
> * A lot of changes are about white space / reformatting or insignificant
> things as replacing angle brackets with round ones.  Especially in LISP
> languages, where this amounts to large line wise diff's for no
> structural reason.

Yes, that's bad. Sorry, I can't stand angle brackets anymore.

> 
> * One simple "bug" is still there:
> 
> (define make-mutex
>   (lambda id
>     (let* ((id (if (pair? id) (car id) (gensym 'mutex)))
>          (m (##sys#make-mutex id ##sys#current-thread)) )
>       m) ) )
> 
> Even though it seems not too hurt too much, it's very bad,
> because it keeps a reference to the thread, which created the mutex
> within the mutex for no good (enough) reason.  So far the creating
> thread does not own the mutex or has any special relation to it I can
> seen.
> 
> And if everything would always go the most expected way, one would
> rarely notice.  But what's going to happen, if one creates threads,
> which create mutexes (which they pass elsewhere for further reference)
> and then rely on finalizers to clean up the resources they reference?
> 
> The programmer knows the thread to be dead and since there's no
> reference left, expects the resources to be freed.  The mutex however
> keeps an unused reference and hence just that's not the case.
> 
> For me: after a while there are no more file descriptors left.
> 
> So why not:
> 
> (define make-mutex
>   (lambda id
>     (let* ((id (if (pair? id) (car id) (gensym 'mutex)))
>          (m (##sys#make-mutex id #f)) )
>       m) ) )
> 
> Its even 18 characters shorter.
> 

Thanks, Joerg. I have changed this accordingly.


cheers,
felix