Property for number of threads to use

[Peter Peterson]

As many developer have hyper-threading turned on, and users may want to run more than one instance of mantid on a multi-user machine, add a new property to limit the total number of threads that openMP will use. OpenMP has the ability built in described ​here that limits the number of threads in the next openmp call. Otherwise OPENMP_NUM_THREADS is an environment variable that will limit the the application will use altogether.

[Nick Draper]

Bulk move of tickets at the end of iteration 28

[Vickie Lynch]

(In [11218]) Refs #2808 Properties file variable MultiThreaded.MaxCores sets the maximum number of threads for OpenMP and ThreadPool to use

[Vickie Lynch]

(In [11219]) Refs #2808 Changes meant for branch not trunk

[Vickie Lynch]

(In [11299]) Refs #2808 Properties file variable MultiThreaded.MaxCores sets the maximum number of threads for OpenMP and ThreadPool to use

[Vickie Lynch]

Added variable to Properties File wiki page

[Peter Peterson]

I reviewed the source and it looks good. The one dangling issue is in MultiThreaded.h the macro

#define PARALLEL_SET_NUM_THREADS omp_set_num_threads(MaxCores);

requires that callers have a variable in scope called MaxCores. Modify the macro to take the variable as an argument and modify Algorithm.cpp, then this ticket can be closed.

[Vickie Lynch]

(In [12874]) Refs #2808 Adding argument for macro

[Vickie Lynch]

I ran LoadEventNexus with/without MultiThreaded.MaxCores = 2 and it used the correct number of cores.

[Martyn Gigg]

Confirmed that the property causes the correct number of cores to be used and the macro change is there.

[Stuart Campbell]

This ticket has been transferred to github issue ​3655