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MPI_Query_thread - Returns the current level of thread support
#include <mpi.h>
int MPI_Query_thread(int *provided)
USE MPI
! or the older form: INCLUDE ’mpif.h’
MPI_QUERY_THREAD(PROVIDED, IERROR)
INTEGER PROVIDED, IERROR
USE mpi_f08
MPI_Query_thread(provided, ierror)
INTEGER, INTENT(OUT) :: provided
INTEGER, OPTIONAL, INTENT(OUT) :: ierror
- provided
- C/Fortran only: Level of thread support (integer).
- IERROR
- Fortran only: Error status (integer).
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.
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.
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.
MPI_Init
MPI_Init_thread
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