MPI_Request_free(3) MPI MPI_Request_free(3) NAME MPI_Request_free - Frees a communication request object SYNOPSIS int MPI_Request_free(MPI_Request *request) INPUT/OUTPUT PARAMETERS request - communication request (handle) NOTES This routine is normally used to free inactive persistent requests created with either MPI_Recv_init or MPI_Send_init and friends. It is also permis- sible to free an active request. However, once freed, the request can no longer be used in a wait or test routine (e.g., MPI_Wait ) to determine completion. This routine may also be used to free a non-persistent requests such as those created with MPI_Irecv or MPI_Isend and friends. Like active persis- tent requests, once freed, the request can no longer be used with test/wait routines to determine completion. THREAD AND INTERRUPT SAFETY This routine is thread-safe. This means that this routine may be safely used by multiple threads without the need for any user-provided thread locks. However, the routine is not interrupt safe. Typically, this is due to the use of memory allocation routines such as malloc or other non-MPICH runtime routines that are themselves not interrupt-safe. 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 inte- ger 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 state- ment. 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 ar- gument. Before the value is returned, the current MPI error handler is called. By default, this error handler aborts the MPI job. The error han- dler 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 guarantee 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_REQUEST - Invalid MPI_Request . Either null or, in the case of a MPI_Start or MPI_Startall , not a persistent request. MPI_ERR_OTHER - Other error; use MPI_Error_string to get more information about this error code. SEE ALSO MPI_Isend, MPI_Irecv, MPI_Issend, MPI_Ibsend, MPI_Irsend, MPI_Recv_init, MPI_Send_init, MPI_Ssend_init, MPI_Rsend_init, MPI_Wait, MPI_Test, MPI_Waitall, MPI_Waitany, MPI_Waitsome, MPI_Testall, MPI_Testany, MPI_Test- some 4/10/2026 MPI_Request_free(3)
NAME | SYNOPSIS | INPUT/OUTPUT PARAMETERS | NOTES | THREAD AND INTERRUPT SAFETY | NOTES FOR FORTRAN | ERRORS | SEE ALSO
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