# MPI_Init_thread

Initialize the MPI execution environment

## Synopsis

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

## Input Parameters

argc
  Pointer to the number of arguments
argv
  Pointer to the argument vector
required
  Level of desired thread support

## Output Parameters

provided
  Level of provided thread support

## Command line arguments

MPI specifies no command-line arguments but does allow an MPI implementation to make use of them. See `MPI_INIT` for a description of the command line arguments supported by `MPI_INIT` and `MPI_INIT_THREAD`.

## Notes

The valid values for the level of thread support are:

MPI_THREAD_SINGLE
  Only one thread will execute.
MPI_THREAD_FUNNELED
  The process may be multi-threaded, but only the main thread will make MPI calls (all MPI calls are funneled to the main thread).
MPI_THREAD_SERIALIZED
  The process may be multi-threaded, and multiple threads may make MPI calls, but only one at a time: MPI calls are not made concurrently from two distinct threads (all MPI calls are serialized).
MPI_THREAD_MULTIPLE
  Multiple threads may call MPI, with no restrictions.

## Notes for Fortran

Note that the Fortran binding for this routine does not have the `argc` and `argv` arguments. (`MPI_INIT_THREAD(required, provided, ierror)`)

## Errors

All MPI routines (except `MPI_Wtime` and `MPI_Wtick`) return an error value; C routines as the value of the function and Fortran routines in the last argument. Before the value is returned, the current MPI error handler is called. By default, this error handler aborts the MPI job. The error handler may be changed with `MPI_Comm_set_errhandler` (for communicators), `MPI_File_set_errhandler` (for files), and `MPI_Win_set_errhandler` (for RMA windows). The MPI-1 routine `MPI_Errhandler_set` may be used but its use is deprecated. The predefined error handler `MPI_ERRORS_RETURN` may be used to cause error values to be returned. Note that MPI does not guarentee that an MPI program can continue past an error; however, MPI implementations will attempt to continue whenever possible.

MPI_SUCCESS
  No error; MPI routine completed successfully.

MPI_ERR_OTHER
  Other error; use `MPI_Error_string` to get more information about this error code.

## See Also

MPI_Init, MPI_Finalize