MPI_Thread(3)

NAME
     MPI_Thread - Returns MPI thread information


SYNOPSIS
     C:

          #include <mpi.h>

          int MPI_Init_thread(int *argc, char ***argv, int required,
          int *provided);

          int MPI_Query_thread(int *provided);

          int MPI_Is_thread_main(int *flag);


     Fortran:

          INCLUDE "mpif.h" (or USE MPI)

          INTEGER required, provided, ierror
          CALL MPI_INIT_THREAD(required, provided, ierror)

          INTEGER provided
          CALL MPI_QUERY_THREAD(provided)

          LOGICAL flag
          INTEGER ierror
          CALL MPI_IS_THREAD_MAIN(flag, ierror)


DESCRIPTION
     The following MPI_Thread routines return MPI thread information:

     MPI_Init_thread     The MPI_Init_thread routine initializes the MPI
                         execution environment in the same way that a call to
                         MPI_INIT would. In addition, it initializes the
                         thread environment.

                         This routine accepts the following parameters:

                              *   argc, which specifies a pointer to the
                                  number of arguments.

                              *   argv, which specifies a pointer to the
                                  argument vector.

                              *   required, which specifies the desired level
                                  of thread support. The following possible
                                  values are listed in increasing order of
                                  thread support:
                                   MPI_THREAD_SINGLE:  Only one thread will
                                   execute.

                                   MPI_THREAD_FUNNELED:  The process can be
                                   multithreaded, but only the main thread
                                   will make MPI calls.

                                   MPI_THREAD_SERIALIZED:  The process can be
                                   multithreaded, and multiple threads can
                                   make MPI calls, but only one at a time.
                                   MPI calls are not made concurrently from
                                   two distinct threads.

                                   MPI_THREAD_MULTIPLE:  Multiple threads can
                                   call MPI.

                              *   provided, which specifies the actual level
                                  of thread support provided by MPI. It can
                                  have one of the four values in the previous
                                  option list.

     MPI_Query_thread    The MPI_Query_thread routine returns, in provided,
                         the current level of thread support.

     MPI_Is_thread_main  The MPI_Is_thread_main routine can be called by a
                         thread to find out whether it is the main thread. The
                         main thread is the thread that called MPI_Init or
                         MPI_Init_thread.  The answer is returned in flag.

NOTES
     MPI statistics (see the MPI_SGI_stat man page) are not thread safe.

SEE ALSO
     MPI_SGI_stat(3)