MPI\_TESTANY(3) Open MPI MPI\_TESTANY(3) MPI\_Testany — Tests for completion of any one previously initiated communication in a list. # [SYNTAX](#SYNTAX) ## [C Syntax](#C_Syntax) ``` #include int MPI_Testany(int count, MPI_Request array_of_requests[], int *index, int *flag, MPI_Status *status) ``` ## [Fortran Syntax](#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](#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](#INPUT_PARAMETERS) - **count**: List length (integer). - **array\_of\_requests**: Array of requests (array of handles). # [OUTPUT PARAMETERS](#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](#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 <#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](#ERRORS) Almost all MPI routines return an error value; C routines as the return result of the function and Fortran routines in the last argument. Before the error value is returned, the current MPI error handler associated with the communication object (e.g., communicator, window, file) is called. If no communication object is associated with the MPI call, then the call is considered attached to MPI\_COMM\_SELF and will call the associated MPI error handler. When MPI\_COMM\_SELF is not initialized (i.e., before MPI\_Init <#mpi-init>/MPI\_Init\_thread <#mpi-init-thread>, after MPI\_Finalize <#mpi-finalize>, or when using the Sessions Model exclusively) the error raises the initial error handler. The initial error handler can be changed by calling MPI\_Comm\_set\_errhandler <#mpi-comm-set-errhandler> on MPI\_COMM\_SELF when using the World model, or the mpi\_initial\_errhandler CLI argument to mpiexec or info key to MPI\_Comm\_spawn <#mpi-comm-spawn>/MPI\_Comm\_spawn\_multiple <#mpi-comm-spawn-multiple>. If no other appropriate error handler has been set, then the MPI\_ERRORS\_RETURN error handler is called for MPI I/O functions and the MPI\_ERRORS\_ABORT error handler is called for all other MPI functions. Open MPI includes three predefined error handlers that can be used: - **MPI\_ERRORS\_ARE\_FATAL** Causes the program to abort all connected MPI processes. - **MPI\_ERRORS\_ABORT** An error handler that can be invoked on a communicator, window, file, or session. When called on a communicator, it acts as if MPI\_Abort <#mpi-abort> was called on that communicator. If called on a window or file, acts as if MPI\_Abort <#mpi-abort> was called on a communicator containing the group of processes in the corresponding window or file. If called on a session, aborts only the local process. - **MPI\_ERRORS\_RETURN** Returns an error code to the application. MPI applications can also implement their own error handlers by calling: - MPI\_Comm\_create\_errhandler <#mpi-comm-create-errhandler> then MPI\_Comm\_set\_errhandler <#mpi-comm-set-errhandler> - MPI\_File\_create\_errhandler <#mpi-file-create-errhandler> then MPI\_File\_set\_errhandler <#mpi-file-set-errhandler> - MPI\_Session\_create\_errhandler <#mpi-session-create-errhandler> then MPI\_Session\_set\_errhandler <#mpi-session-set-errhandler> or at MPI\_Session\_init <#mpi-session-init> - MPI\_Win\_create\_errhandler <#mpi-win-create-errhandler> then MPI\_Win\_set\_errhandler <#mpi-win-set-errhandler> Note that MPI does not guarantee that an MPI program can continue past an error. See the MPI man page <#open-mpi> for a full list of MPI error codes <#open-mpi-errors>. See the Error Handling section of the MPI-3.1 standard for more information. Note that per the “Return Status” section in the “Point-to-Point Communication” chapter in the MPI Standard <https://www.mpi-forum.org/docs/>, MPI errors on requests passed to MPI\_Testany do not set the **status.MPI\_ERROR** field in the returned *status*. The error code is always 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-comm-set-errhandler> - MPI\_File\_set\_errhandler <#mpi-file-set-errhandler> - MPI\_Test <#mpi-test> - MPI\_Testall <#mpi-testall> - MPI\_Testsome <#mpi-testsome> - MPI\_Wait <#mpi-wait> - MPI\_Waitall <#mpi-waitall> - MPI\_Waitany <#mpi-waitany> - MPI\_Waitsome <#mpi-waitsome> - MPI\_Win\_set\_errhandler <#mpi-win-set-errhandler> # [Copyright](#Copyright) 2003-2026, The Open MPI Community September 23, 2026 --- Document: MPI_Testany(3) from openmpi-cuda-13.0 5.0.11-r0 (Chainguard OS) Source: https://github.com/open-mpi/ompi