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MPI_Query_thread.3.rst

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MPI_Query_thread

:ref:`MPI_Query_thread` |mdash| Returns the current level of thread support

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 :ref:`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

.. seealso::
   * :ref:`MPI_Init`
   * :ref:`MPI_Init_thread`