MPI_COMM_DELETE_ATTR(3)				     Open MPI				   MPI_COMM_DELETE_ATTR(3)

MPI_Comm_delete_attr — Deletes attribute value associated with a key.

SYNTAX
   C Syntax
	  #include <mpi.h>

	  int MPI_Comm_delete_attr(MPI_Comm comm, int comm_keyval)

   Fortran Syntax
	  USE MPI
	  ! or the older form: INCLUDE 'mpif.h'

	  MPI_COMM_DELETE_ATTR(COMM, COMM_KEYVAL, IERROR)
	      INTEGER COMM, COMM_KEYVAL, IERROR

   Fortran 2008 Syntax
	  USE mpi_f08

	  MPI_Comm_delete_attr(comm, comm_keyval, ierror)
	      TYPE(MPI_Comm), INTENT(IN) :: comm
	      INTEGER, INTENT(IN) :: comm_keyval
	      INTEGER, OPTIONAL, INTENT(OUT) :: ierror

   INPUT/OUTPUT PARAMETER
       • comm : Communicator from which the attribute is deleted (handle).

INPUT PARAMETER
       • comm_keyval : Key value (integer).

OUTPUT PARAMETER
       • ierror : Fortran only: Error status (integer).

DESCRIPTION
       MPI_Comm_delete_attr  deletes  an  attribute  from cache by key. This function invokes the attribute delete
       function delete_fn specified when the comm_keyval was created. The call will fail if the delete_fn function
       returns an error code other than MPI_SUCCESS.

       Whenever a communicator is replicated using the function MPI_Comm_dup <#mpi-comm-dup>,  all  callback  copy
       functions  for  attributes that are currently set are invoked (in arbitrary order). Whenever a communicator
       is deleted using the function MPI_Comm_free <#mpi-comm-free>, all callback delete functions for	attributes
       that  are currently set are invoked. This function is the same as MPI_Attr_delete <#mpi-attr-delete> but is
       needed to match the  communicator-specific  functions  introduced  in  the  MPI-2  standard.   The  use	of
       MPI_Attr_delete <#mpi-attr-delete> is deprecated.

NOTES
       Note  that  it  is not defined by the MPI standard what happens if the delete_fn callback invokes other MPI
       functions. In Open MPI, it is not valid for delete_fn callbacks (or any of their children) to add or delete
       attributes on the same object on which the delete_fn callback is being invoked.

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.

Copyright
       2003-2026, The Open MPI Community

						   Mar 05, 2026				   MPI_COMM_DELETE_ATTR(3)
