[CppAD] Multithreading

[Brad Bell]

The helgrind warning below was in fact a race condition and it has been 
fixed. See the heading 04-01 on
     http://www.coin-or.org/CppAD/Doc/whats_new_12.xml


On 03/24/2012 11:13 AM, Brad Bell wrote:
> This bug,and some other things that Dominik found have been fixed. See 
> the headings 03-21 and 03-23 on
>     http://www.coin-or.org/CppAD/Doc/whats_new_12.htm
>
> There still are some error messages when running
>     valgrind --tool=helgrind ./pthread_test simple_ad
> but they appear to be a problem with valgrind.
>
> To be specific, when in the makefile
>     multi_thread/makefile
> I change
>     # AM_CXXFLAGS     = -g $(CXX_FLAGS)
>       AM_CXXFLAGS = -DNDEBUG -O2 $(CXX_FLAGS)
> to
>     AM_CXXFLAGS     = -g $(CXX_FLAGS)
>     # AM_CXXFLAGS = -DNDEBUG -O2 $(CXX_FLAGS)
> and run
>     make pthread_test
>     valgrind --tool=helgrind ./pthread_test simple_ad
> I get
> ... snip ...
> ==19568== Possible data race during write of size 4 at 0x80770c0 by 
> thread #1
> ==19568==    at 0x8050455: CppAD::AD<double>::tape_new() 
> (tape_link.hpp:221)
> ... snip ...
> ==19568==  This conflicts with a previous read of size 4 by thread #4
> ==19568==    at 0x805450A: CppAD::AD<double>::id_handle(unsigned int) 
> (tape_link.hpp:73)
> ... snip ...
>
>