Threads + pipes = bad?

Threads + pipes = bad?

[Robert Marlow]

Hi all 

I'm getting some problems with my use of a pipe within a thread in a
program I'm writing. Platform is Solaris 8.

Anyway, here's an example of a function I've called from within the
thread:

(define (email message)
  (let* ((address (assoc-ref message 'address))
         (message-text (assoc-ref message 'text))
         (mail-pipe (open-output-pipe (string-append "mailx -s \'" 
                                                     subject "\' "
				                     address)))
   (display message-text mail-pipe)
   (close-pipe))) 


And here's the errors I get:

In thread:
ERROR: In procedure dup2:
ERROR: Bad file number

and 

In thread:
ERROR: In procedure waitpid:
ERROR: No child processes


Can anyone shed some light on what's happening here? Is there contention
for file descriptors or something?

TIA


-- 
Regards,

Robert Marlow







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Re: Threads + pipes = bad?

[Robert Marlow]

Nevermind, I think I fixed it by calling the function while the mutex
was locked. Bummar though; the whole point of using threads was to get
procedures like this one working concurrently.

I haven't really played with threads before... is there any reason I
shouldn't be able to unlock the mutex and _then_ call a procedure with a
pipe such as below? 

I'm guessing the way to speed the processing up without taking it out of
the mutex lock is to put the procedure in a separate executable script,
yeah?


On Thu, 2003-07-24 at 15:48, Robert Marlow wrote:
> Hi all 
> 
> I'm getting some problems with my use of a pipe within a thread in a
> program I'm writing. Platform is Solaris 8.
> 
> Anyway, here's an example of a function I've called from within the
> thread:
> 
> (define (email message)
>   (let* ((address (assoc-ref message 'address))
>          (message-text (assoc-ref message 'text))
>          (mail-pipe (open-output-pipe (string-append "mailx -s \'" 
>                                                      subject "\' "
> 				                     address)))
>    (display message-text mail-pipe)
>    (close-pipe))) 
> 
> 
> And here's the errors I get:
> 
> In thread:
> ERROR: In procedure dup2:
> ERROR: Bad file number
> 
> and 
> 
> In thread:
> ERROR: In procedure waitpid:
> ERROR: No child processes
> 
> 
> Can anyone shed some light on what's happening here? Is there contention
> for file descriptors or something?
> 
> TIA
> 
> 
> -- 
> Regards,
> 
> Robert Marlow
> 
> 
> 
> 
> 
> 
> 
> _______________________________________________
> Guile-user mailing list
> Guile-user@gnu.org
> http://mail.gnu.org/mailman/listinfo/guile-user
-- 
Regards,

Robert Marlow



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Re: Threads + pipes = bad?

[Kevin Ryde]

Robert Marlow <bobstopper@australispro.com.au> writes:
>
> Nevermind, I think I fixed it by calling the function while the mutex
> was locked. Bummar though; the whole point of using threads was to get
> procedures like this one working concurrently.

Does your main thread do anything evil?  Without actually trying it,
it seems that open-process might end up with all threads still running
in the forked child (until it exec's).


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Re: Threads + pipes = bad?

[Robert Marlow]

My main process just brings up a few threads and then sits back in a
while loop doing nothing.

Actually, select's throwing file number errors at me as well. It seems
whenever I use a port, if it's outside a mutex lock it complains.


On Tue, 2003-07-29 at 07:11, Kevin Ryde wrote:
> Does your main thread do anything evil?  Without actually trying it,
> it seems that open-process might end up with all threads still running
> in the forked child (until it exec's).
-- 
Regards,

Robert Marlow







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