c – MPI_Comm_spawn和MPI_Reduce

我有两个程序.生成“工人”的“主人”执行一些计算,我希望主人从工人那里得到结果并存储金额.我正在尝试使用MPI_Reduce来收集工作者的结果,并且工作人员使用MPI_Reduce发送给主人MPI_Comm.我不确定这是否正确.这是我的节目：

主：

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

int main(int argc,char *argv[]) { 
    int world_size,universe_size,*universe_sizep,flag; 

    int rc,send,recv;

    // intercommunicator
    MPI_Comm everyone;

    MPI_Init(&argc,&argv); 
    MPI_Comm_size(MPI_COMM_WORLD,&world_size); 

    if (world_size != 1) {
        cout << "Top heavy with management" << endl;
    } 

    MPI_Attr_get(MPI_COMM_WORLD,MPI_UNIVERSE_SIZE,&universe_sizep,&flag);  
    if (!flag) { 
        cout << "This MPI does not support UNIVERSE_SIZE. How many processes total?";
        cout << "Enter the universe size: ";
        cin >> universe_size; 
    } else {
        universe_size = *universe_sizep;
    }
    if (universe_size == 1) {
        cout << "No room to start workers" << endl;
    }

    MPI_Comm_spawn("so_worker",MPI_ARGV_NULL,universe_size-1,MPI_INFO_NULL,MPI_COMM_SELF,&everyone,MPI_ERRCODES_IGNORE);

    send = 0;

    rc = MPI_Reduce(&send,&recv,1,MPI_INT,MPI_SUM,everyone);

    // store result of recv ...
    // other calculations here
    cout << "From spawned workers recv: " << recv << endl;

    MPI_Finalize(); 
    return 0; 
}

工人：

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

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

    int rc,recv;


    int parent_size,parent_id,my_id,numprocs; 
    // parent intercomm
    MPI_Comm parent; 
    MPI_Init(&argc,&argv); 

    MPI_Comm_get_parent(&parent); 
    if (parent == MPI_COMM_NULL) {
        cout << "No parent!" << endl;
    }
    MPI_Comm_remote_size(parent,&parent_size); 
    MPI_Comm_rank(parent,&parent_id) ; 
    //cout << "Parent is of size: " << size << endl;
    if (parent_size != 1) {
        cout << "Something's wrong with the parent" << endl;
    }

    MPI_Comm_rank(MPI_COMM_WORLD,&my_id) ;     
    MPI_Comm_size(MPI_COMM_WORLD,&numprocs) ;  

    cout << "I'm child process rank "<< my_id << " and we are " << numprocs << endl;
    cout << "The parent process rank "<< parent_id << " and we are " << parent_size << endl;

    // get value of send
    send = 7; // just an example
    recv = 0;

    rc = MPI_Reduce(&send,parent);
    if (rc != MPI_SUCCESS)
        cout << my_id << " failure on mpi_reduce in WORKER" << endl;

    MPI_Finalize(); 
    return 0; 
}

我编译了两个并像这样执行(mpx for osx)：

mpic++ so_worker.cpp -o so_worker
mpic++ so_master.cpp -o so_master
mpirun -n 1 so_master

这是运行产生工人的主人的正确方法吗？

在Master中我总是从MPI_Reduce返回0.我可以使用来自intercommunicators的MPI_reduce,还是应该使用来自worker的MPI_Send和来自master的MPI_Recv？我真的不确定为什么它不起作用.

任何帮助,将不胜感激.谢谢！

I'm child process rank 0 and we are 3
The parent process **rank 0** and we are 1
I'm child process rank 1 and we are 3
The parent process **rank 1** and we are 1
I'm child process rank 2 and we are 3
The parent process **rank 2** and we are 1

//
// Worker code
//
rc = MPI_Reduce(&send,parent);

//
// Master code
//
rc = MPI_Reduce(&send,MPI_ROOT,everyone);