CODEWITHSUNDEEP
parallel-processingmpi
shaikh
shaikh

Reputation: 592

send/receive object arrays using MPI

Is it possible to send/receive C++ object and object arrays using MPI_Bcast, MPI_Scatter and MPI_Gather. If yes then which MPI datatype is used for objects? For example I have a class named cell.

class cell
{
private:        
  int abc;
  double xyz;

public:
    cell(){ }                
     ...
};

In the main function, I would like to make an object array of class cell and would like to send/receive as object array. e.g.,

void main ()
{
...
    cell** cells = new cell*[someVar];
        for(int i = 0; i < someVar; ++i) 
        {
            cells[i] = new cell[someVar];
        }
MPI_Bcast(cells, someVar, ???, 0, MPI_COMM_WORLD);
...
}

How can we define an MPI data type to send / receive an object array?

Upvotes: 1

Views: 1995

Answers (1)

Victor Eijkhout
Victor Eijkhout

Reputation: 5794

Check out the MPI_Pack / MPI_Unpack mechanism. On the sending side you stuff the elements into a pack buffer and you send that; the receiving side unpacks it component-by-component. This offers such cute possibilities as first unpacking an integer that tells you how many subsequent doubles there are to unpack. A big advantage of this approach is that it applies to objects that are only indirectly accessible through an iterator or such.

Upvotes: 1

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