petsc-3.10.5 2019-03-28

PetscSequentialPhaseBegin

Begins a sequential section of code.

Synopsis

#include "petscsys.h"  
PetscErrorCode  PetscSequentialPhaseBegin(MPI_Comm comm,int ng)

Collective on MPI_Comm

Input Parameters

	comm	- Communicator to sequentialize.
	ng	- Number in processor group. This many processes are allowed to execute at the same time (usually 1)

Notes

PetscSequentialPhaseBegin() and PetscSequentialPhaseEnd() provide a way to force a section of code to be executed by the processes in rank order. Typically, this is done with

      PetscSequentialPhaseBegin(comm, 1);
      <code to be executed sequentially>
      PetscSequentialPhaseEnd(comm, 1);

Often, the sequential code contains output statements (e.g., printf) to be executed. Note that you may need to flush the I/O buffers before calling PetscSequentialPhaseEnd(). Also, note that some systems do not propagate I/O in any order to the controling terminal (in other words, even if you flush the output, you may not get the data in the order that you want).

Level

intermediate

Location