Re: [Openexr-devel] Thread safety

[Bob Friesenhahn]

On Wed, 3 Apr 2013, Christopher Horvath wrote:
> My vote for the default would be to use the std::thread library, as part of the 
> C++11 standard. 

Given that it is only 2013 now, hardly anyone can be assured to have 
C++11 threads or even a compliant compiler.

OpenMP 2.0 is quite widely available and solid except that 'clang' 
does not seem to support it yet (other than via llvm-gcc wrapper). 
The fact that it is based on pragmas should not cause any fear. The 
ability to build the code without OpenMP is a considerable benefit.

OpenMP supports efficient lock primitives but does not support 
condition variables yet (as far as I am aware) so waiting/queuing 
between threads is not as effective as it might be. Such designs are 
best avoided unless it is ok to rely on the pthreads API.  My own 
software is currently depending on the pthreads API for some of its 
locking (without problems).

If OpenEXR depends on an add-on library for its threading, one would 
hope that the library is very portable, open sourced, easy to compile, 
and that its usage license is compatible with OpenEXR's existing 
license.

Bob
--
Bob Friesenhahn
address@hidden, http://www.simplesystems.org/users/bfriesen/
GraphicsMagick Maintainer,    http://www.GraphicsMagick.org/