Subj : Re: Are locks taken when using TLS
To   : comp.programming.threads
From : roger.faulkner
Date : Wed Apr 13 2005 09:45 am


Robert wrote:
> Hi
>
> I was wondering if there are any contention an locking issues
> when using Thread local Storage
> e.g. is a lock taken when doing pthread_getspecific
>
> I believe it is not like this in windows but how does this work on
> e.g Linux ,AIX, Solaris, and HPUX is it the same?
>
> help in clearing this out would be very much appreachiated
>
> kind regards Robert

Terminology correction:

TLS == Thread Local Storage == thread-local data allocated with help
from the compiler (using the '__thread' keyword).

TSD == Thread Specific Data == stuff created by pthread_key_create()
and pthread_setspecific() and returned by pthread_getspecific()

To answer the question for Solaris:

There is no locking involved in pthread_getspecific().
The interface has no contention and is quite fast.

Roger Faulkner
Sun Microsystems

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