Re: Thread_Id

[RVK <rvk@prodmail.net>]

Arjan van de Ven wrote:

> On Thu, 2005-07-14 at 15:36 +0530, RVK wrote:
>
>  
>
> > > it doesn't return a number it returns a pointer ;) or a floating point
> > > number. You don't know :)
> > >
> > > what it returns is a *cookie*. A cookie that you can only use to pass
> > > back to various pthread functions.
> > >
> > >
> > >
> > >      
> > Hahaha......common. Please clarify following....
> >    
>
> I'm missing the joke
>
>  
Its not a joke its a confusion created by the thread identifier.

> > SYNOPSIS
> >       #include <pthread.h>
> >
> >       pthread_t pthread_self(void);
> >
> > DESCRIPTION
> >       pthread_self return the thread identifier for the calling thread.
> >    
>
> *identifier*.
> It doesn't give a meaning beyond that, and if you look at other pthread
> manpages (say pthread_join) it just wants that identifier back. If you
> want to attach meaning to a thread identifier, please come up with a
> manpage/standard that actually defines the meaning of it.
>
>  
>
> > bits/pthreadtypes.h:150:typedef unsigned long int pthread_t;
> >    
>
> and here you
> 1) look at implementation details of your specific threading
> implementation and
> 2) you prove that your analysis is wrong since the implementation you
> look at defines it as *unsigned* so it can't be negative. So what your
> app does is clearly wrong even within the implementation you look at.
>
>
>  
So then what is the meaning of that typedef and why its still there ?

> Other implementations are allowed to use different types for this. In
> fact, I'd be surprised if NPTL and LinuxThreads would have the same
> type... (they'll have the same size for ABI compat reasons of course,
> but type... not so sure).
>
>  
I haven't faced the same returns with 2.4.18. So why is it so with 2.6.x 
kernels ? pthread_self() on 2.4.18 was returning the same as gettid() 
with 2.6.x.

rvk

> .
>
>  

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