问当使用MPI时，并行eclipse不识别真正数量的处理器。

EN

#include <iostream>
#include <mpi.h>
using namespace std;

int main(int argc, char* argv[])
{

    MPI_Init(&argc, &argv);

    int rank;
    MPI_Comm_rank(MPI_COMM_WORLD, &rank);

    int size;
    MPI_Comm_size(MPI_COMM_WORLD, &size);
    int data;

    if (rank > 0) {

        MPI_Recv(&data, 1, MPI_INT, rank-1, 0, MPI_COMM_WORLD,MPI_STATUS_IGNORE);
                cout << "Rank "<< rank<< " has received message with data " << data
                        << " from rank " << rank-1
                        << endl;
    }

    cout << "Hello from rank " << rank<< " out of " << size<< endl;

    if (rank < size-1) {
        data = rank*rank;

        MPI_Send(&data, 1, MPI_INT, rank+1, 0, MPI_COMM_WORLD);
    }

    MPI_Finalize();
    return 0;
}

mpic++ -o name name.cpp
mpiexec -np 4 ./name

Hello from rank 0 out of 4
Rank 1 has received message with data 0 from rank 0
Hello from rank 1 out of 4
Rank 2 has received message with data 1 from rank 1
Hello from rank 2 out of 4
Rank 3 has received message with data 4 from rank 2
Hello from rank 3 out of 4