NAME

       MPI_Is_thread_main - Determines if thread called MPI_Init

SYNTAX

C Syntax

       #include <mpi.h>
       int MPI_Is_thread_main(int *flag)

Fortran Syntax

       USE MPI
       ! or the older form: INCLUDE 'mpif.h'
       MPI_IS_THREAD_MAIN(FLAG, IERROR)
            LOGICAL   FLAG
            INTEGER   IERROR

Fortran 2008 Syntax

       USE mpi_f08
       MPI_Is_thread_main(flag, ierror)
            LOGICAL, INTENT(OUT) :: flag
            INTEGER, OPTIONAL, INTENT(OUT) :: ierror

C++ Syntax

       #include <mpi.h>
       bool MPI::Is_thread_main()

OUTPUT PARAMETERS

       flag      True if calling thread is main thread (boolean).

       IERROR    Fortran only: Error status (integer).

DESCRIPTION

       MPI_Is_thread_main  is called by a thread to find out whether the caller is the main thread (that is, the
       thread that called MPI_Init or MPI_Init_thread).

ERRORS

       Almost all MPI routines return an error value; C routines as  the  value  of  the  function  and  Fortran
       routines in the last argument. C++ functions do not return errors. If the default error handler is set to
       MPI::ERRORS_THROW_EXCEPTIONS,  then  on  error  the  C++  exception  mechanism  will  be used to throw an
       MPI::Exception object.

       Before the error value is returned, the current MPI error handler  is  called.  By  default,  this  error
       handler  aborts  the  MPI  job,  except  for  I/O  function errors. The error handler may be changed with
       MPI_Comm_set_errhandler; the predefined error handler MPI_ERRORS_RETURN may be used to cause error values
       to be returned. Note that MPI does not guarantee that an MPI program can continue past an error.

       See the MPI man page for a full list of MPI error codes.

SEE ALSO

       MPI_Init
       MPI_Init_thread

4.1.6                                             Sep 30, 2023                             MPI_Is_thread_main(3)