[Python-Dev] pthreads question: typedef ??? pthread_t and hacky return statements

[Mark Favas]

OK - 

return (long) threadid;

compiles without warnings, and all tests pass on OSF/1 (aka Tru64 Unix).
Removing the "volatile" is also fine for me, but may affect Vladimir.
I'm still a bit (ha!) confused by Tim's comments that the function is
bogus for OSF/1 because it throws away half the bits, and will therefore
result in id collisions - this will only happen on platforms where
sizeof(long) is less than sizeof(pointer), which is not OSF/1 (but is
Win64). Also, one of the suggested tests only cast the pointer to a long
SIZEOF_PTHREAD_T < SIZEOF_LONG - that should surely be <= ...

In summary, whatever issue there was for OSF/1 six (or so) years ago
appears to be no longer relevant - but there will be the truncation
issue for Win64-like platforms.

Mark

Fredrik Lundh wrote:
> 
> trent mick wrote:
> >     return (long) *(long *) &threadid;
> 
> from what I can tell, pthread_t is a pointer under OSF/1.
> 
> I've been using OSF/1 since the early days, and as far as I can
> remember, you've never needed to use stupid hacks like that
> to convert a pointer to a long integer. an ordinary (long) cast
> should be sufficient.
> 
> > Could this be changed to
> >   return threadid;
> > safely?
> 
> safely, yes.  but since it isn't a long on all platforms, you might
> get warnings from the compiler (see Mark's mail).
> 
> :::
> 
> from what I can tell, it's compatible with a long on all sane plat-
> forms (Win64 doesn't support pthreads anyway ;-), so I guess the
> right thing here is to remove volatile and simply use:
> 
>     return (long) threadid;
> 
> (Mark: can you try this out on your box?  setting up a Python 2.0
> environment on our alphas would take more time than I can spare
> right now...)
> 
> </F>

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