NAME

       MPI_Testall -  Tests for the completion of all previously initiated requests

SYNOPSIS

       int MPI_Testall(int count, MPI_Request array_of_requests[], int *flag,
       MPI_Status *array_of_statuses)

INPUT PARAMETERS

       count  - count (non-negative integer)

INPUT/OUTPUT PARAMETERS

       array_of_requests
              - array of requests (handle)

OUTPUT PARAMETERS

       flag   - flag (logical)
       array_of_statuses
              - array of status objects (Status)

NOTES

       flag  is  true  only  if  all  requests  have  completed.   Otherwise,  flag  is  false  and  neither the
       array_of_requests nor the array_of_statuses is modified.

       If one or more of the requests completes with an error, MPI_ERR_IN_STATUS is returned.   An  error  value
       will  be  present is elements of array_of_statuses associated with the requests.  Likewise, the MPI_ERROR
       field in the  status  elements  associated  with  requests  that  have  successfully  completed  will  be
       MPI_SUCCESS .  Finally, those requests that have not completed will have a value of MPI_ERR_PENDING .

       While it is possible to list a request handle more than once in the array_of_requests , such an action is
       considered erroneous and may cause the program to unexecpectedly terminate or produce incorrect results.

NOTES ON THE MPI_STATUS ARGUMENT

       The  MPI_ERROR  field  of  the  status  return  is  only  set  if  the  return  from  the  MPI routine is
       MPI_ERR_IN_STATUS .  That error class is only returned by the routines  that  take  an  array  of  status
       arguments ( MPI_Testall , MPI_Testsome , MPI_Waitall , and MPI_Waitsome ).  In all other cases, the value
       of  the  MPI_ERROR  field in the status is unchanged.  See section 3.2.5 in the MPI-1.1 specification for
       the exact text.

       For send operations, the only use of status is for MPI_Test_cancelled or in the case  that  there  is  an
       error  in  one of the four routines that may return the error class MPI_ERR_IN_STATUS , in which case the
       MPI_ERROR field of status will be set.  In that case, the value will be set to MPI_SUCCESS for  any  send
       or  receive operation that completed successfully, or MPI_ERR_PENDING for any operation which has neither
       failed nor completed.

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 integer 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 statement.

       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 argument.  Before the value is returned, the current MPI error
       handler is called.  By default, this error handler aborts the MPI job.  The error handler 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_ARG
              -  Invalid  argument.   Some  argument  is invalid and is not identified by a specific error class
              (e.g., MPI_ERR_RANK ).
       MPI_ERR_COUNT
              - Invalid count argument.  Count arguments must be non-negative; a count of zero is often valid.
       MPI_ERR_IN_STATUS
              - The actual error value is in the MPI_Status argument.  This error class is  returned  only  from
              the  multiple-completion  routines  (  MPI_Testall  ,  MPI_Testany  , MPI_Testsome , MPI_Waitall ,
              MPI_Waitany , and MPI_Waitsome ).  The field MPI_ERROR in the status argument contains  the  error
              value  or  MPI_SUCCESS (no error and complete) or MPI_ERR_PENDING to indicate that the request has
              not completed.  The MPI Standard does not specify what  the  result  of  the  multiple  completion
              routines  is when an error occurs.  For example, in an MPI_WAITALL , does the routine wait for all
              requests to either fail or complete, or does it return immediately (with  the  MPI  definition  of
              immediately, which means independent of actions of other MPI processes)?  MPICH has chosen to make
              the return immediate (alternately, local in MPI terms), and to use the error class MPI_ERR_PENDING
              (introduced  in  MPI  1.1) to indicate which requests have not completed.  In most cases, only one
              request with an error will be detected in  each  call  to  an  MPI  routine  that  tests  multiple
              requests.   The  requests  that  have  not been processed (because an error occurred in one of the
              requests) will have their MPI_ERROR field marked with MPI_ERR_PENDING .

       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.

                                                    2/9/2024                                      MPI_Testall(3)