Parallel Computing

Warning

This functionality is a work in progress.

It is only available for NETGEN.

It is only available in TUI.

The goal here is to speed up computation by running sub-meshes in parallel (multi-threading).

Concept

In order to parallelise the computation of the mesh we split the geometry into:

• A 1D+2D compound

• A list of 3D solids

Then create a sub-mesh for each of those geometry. And associate Hypothesis to the mesh using a hypothesis on the whole geometry

We will first compute sequentially the 1D+2D compound with NETGEN_1D2D.

Then we will compute all the solids in parallel. Having done the 1D+2D first ensure that all the solids can be computed without any concurrency.

How to

You follow the same principle as the creation of a sequential Mesh.

1. First you create the mesh:

   par_mesh = smesh.ParallelMesh(my_geom, name="par_mesh")
   

2. Define the Global Hypothesis that will be split into an hypothesis for the 1D+2D compound and one for each of the 3D solids:

NETGEN_3D_Parameters_1 = smesh.CreateHypothesisByAverageLength( 'NETGEN_Parameters',
                                 'NETGENEngine', 34.641, 0 )
par_mesh.AddGlobalHypothesis(NETGEN_3D_Parameters_1)

3. Set the method for the parallelisation:

You have two methods for parallelisation:

• Multihtreading: Will run the computation on your computer using the processors on your computer.

par_mesh.SetParallelismMethod(smeshBuilder.MULTITHREAD)

• MultiNodal: Will run the computation on a remote resource (cluster) that is defined in your salome catalog.

par_mesh.SetParallelismMethod(smeshBuilder.MULTINODE)

4. Set the parameters for the parallelism:

• Multithread:

  param = par_mesh.GetParallelismSettings()
  param.SetNbThreads(6)
  

• Multinode:

param = par_mesh.GetParallelismSettings()
param.SetResource("cronos")
param.SetNbProc(nbox**3)
param.SetNbProcPerNode(2)
param.SetNbNode(6)
param.SetWcKey("P11N0:SALOME_COFEE")

5. Compute the mesh:

   is_done = par_mesh.Compute()
   if not is_done:
       raise Exception("Error when computing Mesh")
   

See Also a sample script of Creating Parallel Mesh.