# MPI_Info_set

Adds a (key,value) pair to info

## Synopsis

    int MPI_Info_set(MPI_Info info, const char *key, const char *value)

## Input Parameters

info
  info object (handle)
key
  key (string)
value
  value (string)

## Thread and Interrupt Safety

The user is responsible for ensuring that multiple threads do not try to update the same MPI object from different threads. This routine should not be used from within a signal handler.

The MPI standard defined a thread-safe interface but this does not mean that all routines may be called without any thread locks. For example, two threads must not attempt to change the contents of the same `MPI_Info` object concurrently. The user is responsible in this case for using some mechanism, such as thread locks, to ensure that only one thread at a time makes use of this routine.

## Notes for Fortran

All MPI routines in Fortran (except for `MPI_WTIME` and `MPI_WTICK`) have an additional argument `ierr` at the end of the argument list. `ierr` is an integer and has the same meaning as the return value of the routine in C. In Fortran, MPI routines are subroutines, and are invoked with the `call` statement.

All MPI objects (e.g., `MPI_Datatype`, `MPI_Comm`) are of type `INTEGER` in Fortran.

## 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_INFO_KEY
  Invalid or null key string for info.

MPI_ERR_INFO_VALUE
  Invalid or null value string for info

MPI_ERR_INTERN
  This error is returned when some part of the MPICH implementation is unable to acquire memory.