[wyunyu]

Hello, everyone!
I recently encountered a problem. I need to insert a serial operation into parallel computing. And I used some functions in MPI to do it as the following codes. But I found that the modified data in serial process is not passed to other processes. So how can I make the modified data in the serial pass to other processes? Thank you!

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

 int i(0);
 int numprocs;
 int myid;
 MPI_Status stat;
 MPI_Init(&argc, &argv);
 MPI_Comm_size(MPI_COMM_WORLD,&numprocs);  
 MPI_Comm_rank(MPI_COMM_WORLD,&myid);

// there is N data altogether in testNumber
volScalarField testNumber
(
    IOobject
    (
        "testNumber",
        runTime.timeName(),
        mesh,
        IOobject::NO_READ,
        IOobject::AUTO_WRITE
    ),
    mesh
);

if(myid==0)
{

  for(i=0;i<N;i++)
  {
    testNumber[i]=i;
  }

}

testNumber.write();
// It is found that only the testNumber in the 0 process has been modified, 
//and the testNumber of other processes remains unchanged.

}