c++ - MPI 如何从slave中返回动态数组

Question

用MPI写一个小的并行程序，想从root发送不同的数据到不懂的slave上，然后再slave上生成不同的动态数组，然后将这些动态数组返回到root上。但是在root下接收的时候触发了断点。请各位指教，谢谢！

代码如下：

#include <mpi.h>
#include <iostream>
#include <time.h>
#include <stdlib.h>

int main(int argc, char** argv)
{
    int firstBreakPt, lateralBreakPt;
    //int reMatNum1, reMatNum2;
    int tmpN;

    int breakPt[3][2]={{3,5},{6,9},{4,7}};

    int myid, numprocs;
    MPI_Status status;

//    double *reMat1;
//    double *reMat2;


    MPI_Init(&argc,&argv);
    MPI_Comm_rank(MPI_COMM_WORLD,&myid);
    MPI_Comm_size(MPI_COMM_WORLD,&numprocs);

    tmpN = 15;
    
    if (myid==0)
    {
        // send three parameters to slaves；
        for (int i=1;i<numprocs;i++)
        {
            MPI_Send(&tmpN,1,MPI_INT,i,0,MPI_COMM_WORLD);
        
            firstBreakPt = breakPt[i-1][0];
            lateralBreakPt = breakPt[i-1][1];            

            //std::cout<<i<<" "<<breakPt[i-1][0] <<" "<<breakPt[i-1][1]<<std::endl;

            MPI_Send(&firstBreakPt,1,MPI_INT,i,1,MPI_COMM_WORLD);
            MPI_Send(&lateralBreakPt,1,MPI_INT,i,2,MPI_COMM_WORLD);
        }

        // receive arrays from slaves；
        for (int m =1; m<numprocs; m++)
        {
            MPI_Probe(MPI_ANY_SOURCE, MPI_ANY_TAG, MPI_COMM_WORLD, &status);
            
            if (status.MPI_TAG==3)
            {
                int nElems;
                MPI_Get_elements(&status, MPI_DOUBLE, &nElems);

                // Allocate buffer of appropriate size
                double *result = new double[nElems];
                MPI_Recv(result,nElems,MPI_DOUBLE,m,3,MPI_COMM_WORLD,&status);

                std::cout<<std::endl<<"My id is: "<<m<<", my source is "<< status.MPI_SOURCE<<std::endl;
                for (int ii =0; ii<nElems; ii++)
                {
                    std::cout<<result[ii]<<std::endl;
                }

                //delete [] result;
            } 
            else if (status.MPI_TAG==4) 
            {
                int nElems;
                MPI_Get_elements(&status, MPI_DOUBLE, &nElems);

                // Allocate buffer of appropriate size
                double *result = new double[nElems];
                MPI_Recv(result,nElems,MPI_DOUBLE,m,4,MPI_COMM_WORLD,&status);
                
                std::cout<<std::endl<<"My id is: "<<m<<", my source is "<< status.MPI_SOURCE<<std::endl; // 触发断点；
                for (int ii =0; ii<nElems; ii++)
                {
                    std::cout<<result[ii]<<std::endl;
                }

                //delete [] result;
            }
        }
    }
    else
    {
        // receive three paramters from master;
        MPI_Recv(&tmpN,1,MPI_INT,0,0,MPI_COMM_WORLD,&status);

        MPI_Recv(&firstBreakPt,1,MPI_INT,0,1,MPI_COMM_WORLD,&status);
        MPI_Recv(&lateralBreakPt,1,MPI_INT,0,2,MPI_COMM_WORLD,&status);

        // width
        int width1 = (rand() % (tmpN-firstBreakPt+1))+ firstBreakPt;
        int width2 = (rand() % (tmpN-lateralBreakPt+1))+ lateralBreakPt;

        // create dynamic arrays
        double *reMat1 = new double[width1*width1];
        double *reMat2 = new double[width2*width2];

        for (int n=0;n<width1; n++)
        {
            for (int j=0;j<width1; j++)
            {
                reMat1[n*width1+j]=(double)rand()/RAND_MAX + (double)rand()/(RAND_MAX*RAND_MAX); 
                //a[i*Width+j]=1.00;
            }
        }

        for (int k=0;k<width2; k++)
        {
            for (int h=0;h<width2; h++)
            {
                reMat2[k*width2+h]=(double)rand()/RAND_MAX + (double)rand()/(RAND_MAX*RAND_MAX); 
                //a[i*Width+j]=1.00;
            }
        }

        // send it back to master
        MPI_Send(reMat1,width1*width1,MPI_DOUBLE,0,3,MPI_COMM_WORLD);
        MPI_Send(reMat2,width2*width2,MPI_DOUBLE,0,4,MPI_COMM_WORLD);
    }

    MPI_Finalize();


    return 0;
}