[Openmcl-devel] Problems with RUN-PROGRAM

Gary Byers gb at clozure.com
Tue Nov 19 01:39:04 UTC 2002



On Mon, 18 Nov 2002, Marco Antoniotti wrote:

>
> Hi
>
> OS X 10.2 Jaguar.
>
> ? (run-program "ls" ())
> #<EXTERNAL-PROCESS [552] (EXITED : 0) #x5398B7E>
> ? (run-program "ls" () :output *standard-output*)
>

Somewhat questionably, RUN-PROGRAM's OUTPUT keyword arg defaults to
NIL, which causes any output from the EXTERNAL-PROCESS to be discarded;
it's necessary to say something like:

? (run-program "ls" () :output t)

to get "ls"'s output sent to the listener.  ":OUTPUT T" would probably
be a more reasonable default; I believe that it's at least behaving
as documented.


> ... hangs or displays funky error message (like "Unbound Variable
> \<?>").
>
> Any clues about why this would be failing?
>

There's a usually-dormant lisp thread that's supposed to wake up
whenever an EXTERNAL-PROCESS is created and is supposed to stay
awake as long as some EXTERNAL-PROCESS has pending I/O or unresolved
exit status.

There was a bug in 0.13 whereby that lisp thread went back to sleep
too early; that could explain hanging and other funkiness.  That
was supposed to have been fixed in 0.13.1, and I can't reproduce the
bug with that fix in place.

If you're running 0.13.1 and still see this, I'm puzzled.  If you
can get to a break loop when it's hung, are either of the variables
CCL::*EXTERNAL-PROCESSES* or CCL::*WATCHED-FD-HANDLERS* non-NIL ?
(The "watchdog" thread is supposed to stay awake if so.)




> Cheers
>
> --
> Marco Antoniotti ========================================================
> NYU Courant Bioinformatics Group        tel. +1 - 212 - 998 3488
> 715 Broadway 10th Floor                 fax  +1 - 212 - 995 4122
> New York, NY 10003, USA                 http://bioinformatics.cat.nyu.edu
>                     "Hello New York! We'll do what we can!"
>                            Bill Murray in `Ghostbusters'.
>
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>
>


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