Re: [Chicken-users] busy-wait in tcp-connect

[felix winkelmann]

On 5/17/07, Dan Muresan <address@hidden> wrote:
> Hi,
>
> I've noticed that calling tcp-connect when a single Chicken thread
> exists maxes out the CPU. Try (tcp-connect "1.2.3.4" 80).
>
> In tcp.scm, I see that a thread-block-for-i/o! was commented out:
>
> ;; line 543
>          (let loop ()
>            (let ((f (##net#select-write s)))
>              (when (eq? f -1) (fail))
>              (unless (eq? f 1)
>                ;(##sys#thread-block-for-i/o! ##sys#current-thread s #t)
>                (yield)
>                (loop) ) ) )
>
> I assume that thread-block-for-i/o somehow failed to wake-up in certain
> circumstances, so uncommenting that statement would not be workable?
>
> See also http://www.mail-archive.com/address@hidden/msg03122.html
>
> That message suggests that when connecting to a filtered port (or, in my
> case, a non-existent host) not only will the CPU max out, but the call
> will never time out. This is not good.

That's right. I can't remember now, why the above code was commented
out, but I'll investigate.


cheers,
felix