DB 4.8 introduces some performance enhancements, based on the use
    of shared/exclusive latches instead of locks in some areas of the
    internal buffer management code. This change will affect how the
    DB_MPOOL interface handles dirty buffers.
 Because of these
    changes, DB_MPOOLFILE->get will now
    acquire an exclusive latch on the buffer if
    the DB_MPOOL_DIRTY
    or DB_MPOOL_EDIT flags are specified. This
    could lead to an application deadlock if the application tries to
    fetch the buffer again, without an
    intervening DB_MPOOLFILE->put call.
    If your application uses the DB_MPOOL
    interface, and especially the DB_MPOOL_DIRTY
    and DB_MPOOL_EDIT flags, you should review your
    code to ensure that this behavior change does not cause your
    application to deadlock.