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Re: object file memory

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Kaz Kylheku wrote, On 2/6/2012 5:07 PM:
> On 2012-02-06, Bill M<wpmccormick@just_about_everywhere.com>  wrote:
>> I have an object file foo.o that I want to link to an executable. The
>> main executable creates a number of child threads that use code and
>> variables from foo.o.
>
> Do you have the source code for foo.o that you can tweak and recompile?
Yes
>
>> I've included a very simplistic representation at
>> the end. My question is, how can each child thread (worker) get it's own
>> private copy of global variables foo_char and foo_int? Or does that just
>> happen auto-magically?
>
> Why would that happen automagically? It's completely the wrong thing which
> would break most programs.
>
>> ** foo.c **
>> char foo_char;
>> int foo_int;
>
> These are static variables, which are understood to be single-instance,
> and any correct program relies on them being that way.  Automagically making
> these thread-local would be broken behavior.
>
> GCC has extensions for declaring statics thread local. Check the GCC
> documentation for the setion on "Thread-Local Storage", but the gist of it is:
>
>    __thread char foo_char;
>
> There is also an explicit POSIX API for managing thread-specific values
> accessed by keys: pthread_key_create, pthread_setspecific, etc.

So I just started reading about keys (after my original post here) and I 
was hoping for something even easier. The GCC thread local extensions 
seem pretty simple to implement. I give that a try first.

Thanks!!

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object file memory Bill M <wpmccormick@just_about_everywhere.com> - 2012-02-06 16:41 -0600
  Re: object file memory Kaz Kylheku <kaz@kylheku.com> - 2012-02-06 23:07 +0000
    Re: object file memory Bill M <wpmccormick@just_about_everywhere.com> - 2012-02-07 08:23 -0600
      Re: object file memory Bill M <wpmccormick@just_about_everywhere.com> - 2012-02-07 08:40 -0600
        Re: object file memory Bill M <wpmccormick@just_about_everywhere.com> - 2012-02-07 08:58 -0600
      Re: object file memory Bill M <wpmccormick@just_about_everywhere.com> - 2012-02-07 11:21 -0600
        Re: object file memory "Ersek, Laszlo" <lacos@caesar.elte.hu> - 2012-02-07 22:09 +0100
          Re: object file memory Bill M <wpmccormick@just_about_everywhere.com> - 2012-02-07 16:08 -0600
            Re: object file memory Bill M <wpmccormick@just_about_everywhere.com> - 2012-02-08 20:42 -0600
              Re: object file memory Rainer Weikusat <rweikusat@mssgmbh.com> - 2012-02-09 19:00 +0000
            Re: object file memory Joe Beanfish <joe@nospam.duh> - 2012-02-09 11:15 -0500

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