MPI essentials

Detailed Description

Simplify the initialization/finalization of an MPI environment and the usage of MPI_Comm and MPI_Group objects by wrapping them in C++ classes.

This group provides the building blocks needed by virtually every MPI program:

• mpi::environment is an RAII wrapper that calls MPI_Init in its constructor and MPI_Finalize in its destructor.
• mpi::communicator wraps MPI_Comm and adds convenience methods for rank/size, splitting, duplicating, barrier synchronization (with optional polling to reduce CPU load) and aborting. mpi::shared_communicator is a distinct subtype returned by mpi::communicator::split_shared to make shared-memory APIs type-safe.
• mpi::group wraps MPI_Group with move-only semantics and supports creating sub-groups via mpi::group::include.

A typical Hello world! program using mpi::environment and mpi::communicator can be found in Example 1: Hello world!.

Classes
class	mpi::communicator
	C++ wrapper around MPI_Comm providing various convenience functions. More...
struct	mpi::environment
	RAII class to initialize and finalize MPI. More...
class	mpi::group
	C++ wrapper around MPI_Group providing various convenience functions. More...

Functions
bool	mpi::is_finalized () noexcept
	Check if MPI has been finalized by calling MPI_Finalized.
bool	mpi::is_initialized () noexcept
	Check if MPI has been initialized by calling MPI_Initialized.

Variables
static const bool	mpi::has_env
	Boolean variable that checks if there is an active MPI runtime environment.

Function Documentation

is_finalized()

bool mpi::is_finalized ( )

inlinenodiscardnoexcept

#include <mpi/environment.hpp>

Check if MPI has been finalized by calling MPI_Finalized.

Returns

True if MPI_Finalize has been called, false otherwise.

Definition at line 51 of file environment.hpp.

is_initialized()

bool mpi::is_initialized ( )

inlinenodiscardnoexcept

#include <mpi/environment.hpp>

Check if MPI has been initialized by calling MPI_Initialized.

Returns

True if MPI_Init has been called, false otherwise.

Definition at line 41 of file environment.hpp.

Variable Documentation

has_env

const bool mpi::has_env

static

#include <mpi/environment.hpp>

Initial value:

                          = []() {
  if (std::getenv("OMPI_COMM_WORLD_RANK") != nullptr or std::getenv("PMI_RANK") != nullptr or std::getenv("PMIX_RANK") != nullptr
      or std::getenv("CRAY_MPICH_VERSION") != nullptr or std::getenv("FORCE_MPI_INIT") != nullptr)
    return true;
  else
    return false;
}()

Boolean variable that checks if there is an active MPI runtime environment.

It is true if one of the environment variables OMPI_COMM_WORLD_RANK, PMI_RANK, CRAY_MPICH_VERSION, PMIX_RANK or FORCE_MPI_INIT is set, false otherwise.

Note

The environment variables are set, when a program is executed with mpirun or mpiexec.

Definition at line 65 of file environment.hpp.