[gambit-list] with-output-to-process hangs in OSX

Meng Zhang wsxiaoys.lh at gmail.com
Mon Nov 14 21:15:13 EST 2011


On Tue, Nov 15, 2011 at 10:04 AM, Marc Feeley <feeley at iro.umontreal.ca>wrote:

>
> On 2011-11-14, at 8:40 PM, Meng Zhang wrote:
>
> > >> Below are code I wrote to reproduce the problem
> > >>
> > >> (with-output-to-process
> > >>   (list path: "sed"
> > >>         arguments: '("-e" "s/n/N/g"))
> > >>   (lambda ()
> > >>     (display "nothing")))
> > >>
> >
> > Actually, I can't get your example to run without an error on v4.6.2 .
>  Can I ask you what you expected your code to do?
> > This problem happened in 4.6.1, not 4.6.2
>
> I understand.  But you said that once you upgraded to v4.6.2 the problem
> went away.  But when I try with v4.6.2 I get the same result as v4.6.1 on
> the code above.  So I am wondering why there is a difference on v4.6.2.
>
> > It is sending the text "nothing" to sed's input.  Are you expecting the
> output of sed to appear on the terminal?
> >
> > The procedure with-output-to-process gives to sed a *closed* file
> descriptor for its stdout.  This is why sed complains ("sed: stdout: Broken
> pipe").  If you didn't want this, you can give an stdout-redirection: #f
> setting and sed's stdout will be the same as the interpreter's stdout
> (usually the terminal):
> > In 4.6.1, when I run the code above, the current thread sleeps
> forever.(since the stack frame is at "thread-sleep!")
>
> What happens when you try the code below?
>
> > (with-output-to-process
> >  (list path: "sed"
> >        arguments: '("-e" "s/n/N/g")
> >        stdout-redirection: #f)
> >  (lambda ()
> >    (display "nothing\n")))
>
> Do you get the output on the screen?
>
Yes, it prints "NothiNg" and then fall asleep without exiting.(in 4.6.1)

>
> Marc
>
>


-- 
Zhang Meng
School of Software Engineering, Tongji University
MP: +86 151-2103-2798
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