[Proj] PROJ.4 and OpenMP

[support at mnspoint.com]

Even Rouault kirjoitti 02.07.2015 22:03:
> Le jeudi 02 juillet 2015 20:07:49, support at mnspoint.com a écrit :
>> Hello Jose,
>> 
>> if I remember correctly all what Frank W. did was that he added a 
>> single
>> line containing a mutex object to the source code .. that was all.
> 
>> You
>> might want to run a file comparsion for the first "multithreaded" 
>> proj.4
>> and the version before it .. but just a single line was added I 
>> assume?!
>> 
>> So most likely what you should do is to use that mutex object .. there
>> should be lot of examples about how to use a mutex objects in the
>> network.
> 
> Janne,
> 
> Sorry but I must correct your above statement, since that's just
> misinformation and rather offending regarding FrankW's efforts in that 
> area.
> 
> The changes in proj to make it thread-safe involved touching a lot of 
> files,
> not just one. Just look at the first commit to add thread-safety :
> https://github.com/OSGeo/proj.4/commit/ec678c07c2acb83da8a2187c541b8a2e452dec4b
> And there have been several afterwards.
> 
> If you use the "new" proj API that accept a projCtx argument, no need 
> for a
> mutex.
> 
> Even

Only a single mutex object was added .. and that was all at that point. 
Sure it is possible that something more was done long time before that 
change .. but that was all that could be noticed comparing the versions 
before and after multithreading support!!

Janne.