Is D right for me?

[Sean Kelly]

Jacob Carlborg Wrote:

> On 2010-10-13 07:17, Walter Bright wrote:
> > Denis Koroskin wrote:
> >> Either way, it needs some language support, because currently TLS
> >> implemented on compiler level rather than library level. I proposed
> >> this change in past, but no one responded.
> >
> > Using TLS needs operating system support, and there's special linker
> > support for it and the compiler has to generate TLS references in
> > certain ways in order for it to work.
> >
> > There is no such support in OSX for TLS, and it is done manually by the
> > library. However, TLS access is 10 times slower than on Linux/Windows.
> >
> > Without doing TLS in the operating system standard way, you tend to get
> > hosed if you link with a shared library/DLL that has TLS.
> 
> I don't know how you have implemented TLS on Mac OS X but it does 
> support TLS via the Posix API pthreads. This is the only page from 
> Apple's documentation I could find for now (I'm certain I've seen a 
> better page) 
> http://developer.apple.com/macosx/multithreadedprogramming.html .

Using the Posix API here is tricky because it isn't always documented where the memory resides, so enabling GC scanning of it can be tricky.  Also, default initialization gets a bit weird, etc.  What we really need is for OSX to support the __thread storage class.  We're not alone though, so I think it's likely we'll see it implemented in a future release.