I am now running 2.1.0 branch where the fifo starvation is solved. FYI
the behavior of task scheduling in this branch is as follows. It
begins with all containers scheduled to mappers. Pretty quickly
reducers are starting to be scheduled. From time to time more
containers are given to reducers, until about 50% of available
containers are reducers. It stays 50-50 until all mappers are
scheduled. Only then the proportion of containers allocated to
reducers is increased to > 50%.