[gxy200992243]

Hi, everyone!

I am writing a parallel code. In my code, I have to search for cell label that satisfies certain criteria through the domain, combine the lists obtained by each processor and then distribute the combined list back to each processor.

I know the combination should be done by gatherlist() and the distribution should be done by scatterlist(), but there must be something wrong with my code or my understanding about gatherlist and scatterlist(). My code is like this.

List<label> mylist(100,0);
List<List<label> > t1_first(30,mylist);
List<List<List<label> > > gatherfirst(Pstream::nProcs(), t1_first);
for(label m=0;m<iMesh.C().size();m++)
{
//get the label value for each element in t1_first
//I have checked, the label values for t1_first is right
}
gatherfirst[Pstream::myProcNo()] = t1_first;//Do I need a loop over all the processors here?
Pstream::gatherList(gatherfirst);
Pstream::scatterList(gatherfirst);

Every label in gatherfirst is zero, which is wrong.

Can anyone help me with this problem?

Billions of thanks,

Xiangyu