On the usability of the MPI shared file pointer routines

The MPI-2 standard defines a class of file access routines providing a shared file pointer. All processes using those routines update the same file pointer when accessing the file. Coordination between ranks happens implicitly in the MPI library, relieving the application developer of this responsibility. The shared file pointer routines, however, have found little interest from developers because of several issues ranging from routine usability and portability to performance. We consider the use of these routines in the HDF5 library, a high-level I/O library built on top of MPI, and in Vampir, a performance analysis toolkit. We highlight some of the reasons preventing their adoption and discuss how these routines could be modified to increase their usability. We also propose a novel implementation using the new MPI one-sided routines provided by the upcoming MPI-3.0 standard.