Signal: Segmentation fault (11) Signal code: Invalid permissions (2)

Question

I am creating a 2D vector in process with rank 0. When vector is accessed i get following error "Signal: Segmentation fault (11) Signal code: Invalid permissions (2)".

I tried creating dynamic 2d matrix with malloc, still the error remains same.

following is code snippet -

#include <iostream>
#include <vector>
#include <climits>
#include <mpi.h>

using namespace std;

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

    int num_procs, rank;
    MPI_Init(&argc, &argv);
    MPI_Comm_rank(MPI_COMM_WORLD, &rank);
    MPI_Comm_size(MPI_COMM_WORLD, &num_procs);

    int n1,n2;
    int nodes,edges,source;
    //int **matrix;
    vector<vector<uint32_t>> matrix;
    //take input
    if(rank==0){
        cin>>nodes;
        cin>>edges;
        cin>>source;
        //matrix = (int **)malloc(nodes*nodes*sizeof(int));
        //malloc2D(matrix,nodes,nodes);

        matrix.resize(nodes,vector<uint32_t>(nodes,0));

        cout<<"doing initialization"<<endl;
        fflush(stdout);
        for(int i=0;i<nodes;i++)
            for(int j=0;i<nodes;j++){       
                //segmentation fault occurs here
                matrix[i][j] = INT_MAX;
            }
        cout<<"done initialization"<<endl;
        for(int i=0;i<edges;i++){
            cin>>n1;
            cin>>n2;
            matrix[n1][n2] = 1;
            matrix[n2][n1] = 1;
        }       
    }
    // rest of the code
}

I am resizing the vector with size nodes*nodes. I don't know why sengmentation fault is occuring.

following is error snippet-

doing initialization
[osboxes:02930] *** Process received signal ***
[osboxes:02930] Signal: Segmentation fault (11)
[osboxes:02930] Signal code: Invalid permissions (2)
[osboxes:02930] Failing at address: 0x7fb140021000
[osboxes:02930] [ 0] /lib/x86_64-linux-gnu/libc.so.6(+0x3ef20)[0x7fb1477c8f20]
[osboxes:02930] [ 1] q-3(+0xbe09)[0x561813124e09]
[osboxes:02930] [ 2] /lib/x86_64-linux-gnu/libc.so.6(__libc_start_main+0xe7)[0x7fb1477abb97]
[osboxes:02930] [ 3] q-3(+0xb9fa)[0x5618131249fa]
[osboxes:02930] *** End of error message ***

Please Help!

Answer 1

Wrong condition in the inner loop for(int j=0;i<nodes;j++){ . Have to be for(int j=0;j<nodes;j++){