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Re: object file memory

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Bill M wrote, On 2/7/2012 8:23 AM:
> 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.
>
So after getting the GCC extensions to compile, they appears not work.

I have a global declared as follows:

__thread OCX_COMM_STATE comm_state = OCX_COMM_START;

OCX_COMM_STATE is a typedef'd enum.

So then, in a function called from the main program

comm_state = OCX_COMM_SEND;

But it seems not to change.

Any thoughts? Did I miss something?

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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