[Caml-list] OS X: Trouble with threads + execv

[Caml-list] OS X: Trouble with threads + execv

[Nathaniel Gray]

Hello,

I'm seeing some confusing behavior on OS X (10.3.4) relating to 
pthreads and the execv family of calls.  It appears that when the 
scheduler thread (from otherlibs/systhreads/thread_posix.ml) is 
running, any call to execv will fail with "Operation not supported."  
The same applies to execvp, execve, and execvpe.

Here's a small test program:

--- begin testing.ml ---
open Unix
let args = [| "ocamlc.opt"; "-v" |];;
handle_unix_error (execv "/usr/local/bin/ocamlc.opt") args;;
--- End testing.ml ---

I build with:
ocamlopt -thread unix.cmxa threads.cmxa testing.ml -linkall

The result:
[n8gray@golux tmp]$ a.out
a.out: "execv" failed on "/usr/local/bin/ocamlc.opt": Operation not 
supported

If I build the program without linking to threads.cmxa then it works as 
expected.

Is this expected behavior?

Thanks,
-n8

--
 >>>-- Nathaniel Gray -- Caltech Computer Science ------>
 >>>-- Mojave Project -- http://mojave.cs.caltech.edu -->

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Re: [Caml-list] OS X: Trouble with threads + execv

[Xavier Leroy]

> I'm seeing some confusing behavior on OS X (10.3.4) relating to 
> pthreads and the execv family of calls.  It appears that when the 
> scheduler thread (from otherlibs/systhreads/thread_posix.ml) is 
> running, any call to execv will fail with "Operation not supported."  
> The same applies to execvp, execve, and execvpe.
>
> If I build the program without linking to threads.cmxa then it works as 
> expected.
> Is this expected behavior?

No.  According to POSIX, exec* has no reason to fail if other threads
are still running in the current process.  These other threads are
terminated.  With system threads, Caml's Unix.exec* functions just
call the corresponding system calls.

If you want to make sure, you could try to reproduce this behavior
with a small C program.

- Xavier Leroy

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Re: [Caml-list] OS X: Trouble with threads + execv

[Nathaniel Gray]

On Jul 8, 2004, at 8:09 AM, Xavier Leroy wrote:

>> I'm seeing some confusing behavior on OS X (10.3.4) relating to
>> pthreads and the execv family of calls.  It appears that when the
>> scheduler thread (from otherlibs/systhreads/thread_posix.ml) is
>> running, any call to execv will fail with "Operation not supported."
>> The same applies to execvp, execve, and execvpe.
>>
>> If I build the program without linking to threads.cmxa then it works 
>> as
>> expected.
>> Is this expected behavior?
>
> No.  According to POSIX, exec* has no reason to fail if other threads
> are still running in the current process.  These other threads are
> terminated.  With system threads, Caml's Unix.exec* functions just
> call the corresponding system calls.
>
> If you want to make sure, you could try to reproduce this behavior
> with a small C program.

Thanks.  I was able to reproduce it with a C program so I'll file a bug 
report with Apple.

Cheers,
-Nathan

--
 >>>-- Nathaniel Gray -- Caltech Computer Science ------>
 >>>-- Mojave Project -- http://mojave.cs.caltech.edu -->

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