plucky (3) MPI_Testany.openmpi.3.gz

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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  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_thread,   after
       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 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_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 was called on that communicator. If called on a
         window or file, acts as if 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 then MPI_Comm_set_errhandlerMPI_File_create_errhandler then MPI_File_set_errhandlerMPI_Session_create_errhandler then MPI_Session_set_errhandler or at MPI_Session_initMPI_Win_create_errhandler then MPI_Win_set_errhandler

       Note that MPI does not guarantee that an MPI program can continue past an error.

       See the MPI man page for a full list of MPI error codes.

       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, 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_errhandlerMPI_File_set_errhandlerMPI_TestMPI_TestallMPI_TestsomeMPI_WaitMPI_WaitallMPI_WaitanyMPI_WaitsomeMPI_Win_set_errhandler

       2003-2025, The Open MPI Community

                                                  Feb 17, 2025                                    MPI_TESTANY(3)