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MPI_Testany(3) man page (version 5.0.0rc2)

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Name

MPI_Testany - Tests for completion of any one previously initiated communication in a list.

Syntax

C Syntax


#include <mpi.h>
int MPI_Testany(int count, MPI_Request array_of_requests[],
    int *index, int *flag, MPI_Status *status)

Fortran Syntax


USE MPI
! or the older form: INCLUDE ’mpif.h’
MPI_TESTANY(COUNT, ARRAY_OF_REQUESTS, INDEX, FLAG, STATUS, IERROR)
    LOGICAL    FLAG
    INTEGER    COUNT, ARRAY_OF_REQUESTS(*), INDEX
    INTEGER    STATUS(MPI_STATUS_SIZE), IERROR

Fortran 2008 Syntax


USE mpi_f08
MPI_Testany(count, array_of_requests, index, flag, status, ierror)
    INTEGER, INTENT(IN) :: count
    TYPE(MPI_Request), INTENT(INOUT) :: array_of_requests(count)
    INTEGER, INTENT(OUT) :: index
    LOGICAL, INTENT(OUT) :: flag
    TYPE(MPI_Status) :: status
    INTEGER, OPTIONAL, INTENT(OUT) :: ierror

Input Parameters

count
List length (integer).
array_of_requests
Array of requests (array of handles).

Output Parameters

index
Index of operation that completed, or MPI_UNDEFINED if none completed (integer).
flag
True if one of the operations is complete (logical).
status
Status object (status).
IERROR
Fortran only: Error status (integer).

Description

MPI_Testany tests for completion of either one or none of the operations associated with active handles. In the former case, it returns flag = true, returns in index the index of this request in the array, and returns in status the status of that operation; if the request was allocated by a nonblocking communication call then the request is deallocated and the handle is set to MPI_REQUEST_NULL. (The array is indexed from 0 in C, and from 1 in Fortran.) In the latter case (no operation completed), it returns flag = false, returns a value of MPI_UNDEFINED in index, and status is undefined.

The array may contain null or inactive handles. If the array contains no active handles then the call returns immediately with flag = true, index = MPI_UNDEFINED, and an empty status.

If the array of requests contains active handles then the execution of MPI_Testany(count, array_of_requests, index, status) has the same effect as the execution of MPI_Test(&array_of_requests[i], flag, status), for i=0,1,...,count-1, in some arbitrary order, until one call returns flag = true, or all fail. In the former case, index is set to the last value of i, and in the latter case, it is set to MPI_UNDEFINED. MPI_Testany with an array containing one active entry is equivalent to MPI_Test.

If your application does not need to examine the status field, you can save resources by using the predefined constant MPI_STATUS_IGNORE as a special value for the status argument.

Errors

Almost all MPI routines return an error value; C routines as the value of the function and Fortran routines in the last argument.

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, MPI_File_set_errhandler, or MPI_Win_set_errhandler (depending on the type of MPI handle that generated the request); 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.

Note that per MPI-1 section 3.2.5, MPI errors on requests passed to MPI_TESTANY do not set the status.MPI_ERROR field in the returned status. The error code is passed to the back-end error handler and may be passed back to the caller through the return value of MPI_TESTANY if the back-end error handler returns it. The pre-defined MPI error handler MPI_ERRORS_RETURN exhibits this behavior, for example.

See Also

MPI_Comm_set_errhandler
MPI_File_set_errhandler
MPI_Test
MPI_Testall
MPI_Testsome
MPI_Wait
MPI_Waitall
MPI_Waitany
MPI_Waitsome
MPI_Win_set_errhandler


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