mpi_testany(3)

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

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

C++ Syntax

#include <mpi.h>
static bool Request::Testany(int count, Request array_of_requests[],: int& index, Status& status)
static bool Request::Testany(int count, Request array_of_requests[],: int& index)

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. 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, 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 exceptions 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.

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