Re: Threads vs Processes (was: NuSphere and PostgreSQL

Tom Lane wrote:

>Claudio Natoli <claudio.natoli@memetrics.com> writes:
>
>
>>>How are you dealing with the issue of wanting some static variables to
>>>be per-thread and others not?
>>>
>>>
>
>
>
>>To be perfectly honest, I'm still trying to familiarize myself with the code
>>sufficiently well so that I can tell which variables need to be per-thread
>>and which are shared (and, in turn, which of these need to be protected from
>>concurrent access).
>>
No. Not protected from concurrent access. Each thread must have it's own
copy.

>>
>>
>
>Well, the first-order approximation would be to duplicate the current
>fork semantics: *all* static variables are per-thread, and should be
>copied from the parent thread at thread creation.  If there is some
>reasonably non-invasive way to do that, we'd have a long leg up on the
>problem.
>
There is a declspec(thread) that makes a global variable per-thread.
AFAIK it uses linker magic to replace the actual memory accesses with
calls to TlsAlloc() etc. Note that declspec(thread) doesn't work from
within dynamic link libraries, but that shouldn't be a big problem.

--
    Manfred