Hi Collective WG members and "Groups, Contexts, and Communicators" Committee, We discussed the functionality of a nonblocking communicator duplication during MPI-2.2 and deferred the ticket (#164) to MPI-3 because we didn't want to add too much at that point. This functionality is crucial for the implementation of nonblocking libraries (and the library concept in general) in MPI. For a detailed discussion see Hoefler, Snir: "Writing Parallel Libraries with MPI - Common Practice, Issues, and Extensions". I beefed up the ticket to make it a full MPI-3 ticket and I would like to have a reading at the January meeting. Everybody who is in the "To" field of this message, please review this ticket in the context of the groups and communicators and collectives chapters and comment (also indicate when it's ok). Everybody else on the ML is invited to review too. The collective operations and topologies WG will have another telecon where this ticket is discussed soon. Thanks & Best, Torsten PS: please check if I got your username in the CC field right, and correct it if it is wrong (I didn't find an index for those). -- bash$ :(){ :|:&};: --------------------- http://www.unixer.de/ ----- Torsten Hoefler | Performance Modeling and Simulation Lead Blue Waters Directorate | University of Illinois (UIUC) 1205 W Clark Street | Urbana, IL, 61801 NCSA Building | +01 (217) 244-7736