[Proj] PROJ.4 and OpenMP

support at mnspoint.com support at mnspoint.com
Thu Jul 2 13:07:49 EST 2015

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 



It depends what you are doing if you really need such saftey .. most 
simple programs do not need that .. or they can do the proj.4 interface 
in such a way that there will never be any need to have it thread safe 
.. meaning that the slow speed proj.4 calculations for large data sets 
should be done in forehand before the program enters any hard graphics 
work for example .. and that way it just speeds up to avoid that all 
together! -- but what are you doing dictates that of course.

Regards: Janne.


José Luis García Pallero kirjoitti 02.07.2015 17:25:
> Hello:
> Since version 4.8.0, PROJ.4 has some thread safety facilities
> (https://trac.osgeo.org/proj/wiki/ThreadSafety) and also the source
> code contains an example program in which Posix Threads are used. But
> I'm a bit confused about how to use this thread safety with OpenMP.
> Could someone, please, upload a code example of using PROJ with
> OpenMP? Such example could be also added to the distributed source
> code
> Thanks


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