plucky (3) MPI_Query_thread.openmpi.3.gz

SYNTAX

   C Syntax
          #include <mpi.h>

          int MPI_Query_thread(int *provided)

   Fortran Syntax
          USE MPI
          ! or the older form: INCLUDE 'mpif.h'
          MPI_QUERY_THREAD(PROVIDED, IERROR)
               INTEGER PROVIDED, IERROR

   Fortran 2008 Syntax
          USE mpi_f08
          MPI_Query_thread(provided, ierror)
               INTEGER, INTENT(OUT) :: provided
               INTEGER, OPTIONAL, INTENT(OUT) :: ierror

OUTPUT PARAMETERS

       • provided: C/Fortran only: Level of thread support (integer).

       • ierror: Fortran only: Error status (integer).

DESCRIPTION

       This  routine  returns in provided the current level of thread support.  If MPI was initialized by a call
       to MPI_Init_thread, provided will have the same value as was returned by that function.

       The possible values of provided are as follows:

       MPI_THREAD_SINGLE
              Only one thread may execute.

       MPI_THREAD_FUNNELED
              If the process is multithreaded, only the thread that called MPI_Init[_thread] may make MPI calls.

       MPI_THREAD_SERIALIZED
              If the process is multithreaded, only one thread may make MPI library calls at one time.

       MPI_THREAD_MULTIPLE
              If the process is multithreaded, multiple threads may call MPI at once with no restrictions.

NOTES

       In Open MPI, provided  is  always  MPI_THREAD_SINGLE,  unless  the  program  has  been  linked  with  the
       multithreaded library, in which case provided is MPI_THREAD_MULTIPLE.

ERRORS

       Almost  all  MPI  routines  return  an  error  value; C routines as the return result of the function and
       Fortran routines in the last argument.

       Before the error value is returned, the current MPI  error  handler  associated  with  the  communication
       object  (e.g.,  communicator, window, file) is called.  If no communication object is associated with the
       MPI call, then the call is considered attached to MPI_COMM_SELF and will call the  associated  MPI  error
       handler.   When   MPI_COMM_SELF   is   not  initialized  (i.e.,  before  MPI_Init/MPI_Init_thread,  after
       MPI_Finalize, or when using the Sessions Model exclusively) the error raises the initial  error  handler.
       The  initial  error handler can be changed by calling MPI_Comm_set_errhandler on MPI_COMM_SELF when using
       the World model, or the mpi_initial_errhandler CLI argument to mpiexec or info  key  to  MPI_Comm_spawn/‐
       MPI_Comm_spawn_multiple.   If no other appropriate error handler has been set, then the MPI_ERRORS_RETURN
       error handler is called for MPI I/O functions and the MPI_ERRORS_ABORT error handler is  called  for  all
       other MPI functions.

       Open MPI includes three predefined error handlers that can be used:

       • MPI_ERRORS_ARE_FATAL Causes the program to abort all connected MPI processes.

       • MPI_ERRORS_ABORT An error handler that can be invoked on a communicator, window, file, or session. When
         called on a communicator, it acts as if MPI_Abort was called on  that  communicator.  If  called  on  a
         window  or file, acts as if MPI_Abort was called on a communicator containing the group of processes in
         the corresponding window or file. If called on a session, aborts only the local process.

       • MPI_ERRORS_RETURN Returns an error code to the application.

       MPI applications can also implement their own error handlers by calling:

       • MPI_Comm_create_errhandler then MPI_Comm_set_errhandler

       • MPI_File_create_errhandler then MPI_File_set_errhandler

       • MPI_Session_create_errhandler then MPI_Session_set_errhandler or at MPI_Session_init

       • MPI_Win_create_errhandler then MPI_Win_set_errhandler

       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 the Error Handling section of the MPI-3.1 standard for more information.

       SEE ALSO:

          • MPI_Init

          • MPI_Init_thread

COPYRIGHT

       2003-2025, The Open MPI Community

                                                  Feb 17, 2025                               MPI_QUERY_THREAD(3)