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.. _mpi_t_init_thread:
MPI_T_init_thread
=================
.. include_body
:ref:`MPI_T_init_thread` |mdash| Initializes the MPI Tool information interface
SYNTAX
------
C Syntax
^^^^^^^^
.. code-block:: c
#include <mpi.h>
int MPI_T_init_thread(int required, int *provided)
INPUT PARAMETERS
----------------
* ``required``: Desired level of thread support (integer).
OUTPUT PARAMETERS
-----------------
* ``provided``: Available level of thread support (integer).
DESCRIPTION
-----------
MPI_T_init_thread() initializes the MPI tool information interface.
Calls to MPI tool functions are allowed at any point in execution
(including before MPI_Init() and after MPI_Finalize()) as long
as MPI_T_init_thread() has been called at least once and the number
of calls to MPI_T_init_thread() is greater than the number of calls
to MPI_T_finalize(). If at any point in execution the number of
calls to MPI_T_finalize() equals the number of calls to
MPI_T_init_thread() the MPI tool interface will no longer be
available until another call to MPI_T_init_thread().
MPI_T_init_thread(), like MPI_Init_thread(), has a provision to
request a certain level of thread support in ``required``:
* ``MPI_THREAD_SINGLE``: Only one thread will execute.
* ``MPI_THREAD_FUNNELED``: If the process is multithreaded, only the
thread that called :ref:`MPI_Init_thread` will make MPI calls.
* ``MPI_THREAD_SERIALIZED``: If the process is multithreaded, only one
thread will 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.
The level of thread support available to the program is set in
``provided``. In Open MPI, the value is dependent on how the library was
configured and built. Note that there is no guarantee that ``provided``
will be greater than or equal to ``required``.
NOTES
-----
It is the caller's responsibility to check the value of ``provided``, as
it may be less than what was requested in ``required``.
ERRORS
------
:ref:`MPI_T_init_thread` will fail if:
* ``MPI_T_ERR_MEMORY``: Out of memory
* ``MPI_T_ERR_CANNOT_INIT``: Interface not in the state to be
initialized
.. seealso::
* :ref:`MPI_T`
* :ref:`MPI_Init`
* :ref:`MPI_Init_thread`
|
