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Re: Design hole in nptl (and more general in POSIX threads)



Дана пон, 22-12-2003 у 01:16, Jim Blandy је написао:
...
> 
> When a thread registers itself with the collector, it adds its own
> __thread structure to a global linked list.  The collecting thread
> finds other threads' structures via that global linked list.  So
> there's no problem there.

  What I see as "problem" here is: to know how to find whatever thread
specific data, runtime must (minimally) use pthread_self() to find for
which thread it must lookup; or some data in TLS for same thing. There
is no way __thread can pull this out of thin air - so it's no more async
safe than safer one of these two methods.

  Or maybe runtime implements working way for doing this for every
target platform and is hiding it from you behind __thread abstraction.
Still safer when you know how exactly it works, IMHO. Here is why I
think Boehm did it right - nothing too important is hidden behind
"expected compiler/runtime behaviour".

  dd




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