ReducingBarriersSteps should use ComputerMemory, not MapReduce.

This just hit me like a ton of bricks. Check this:

g.V().count()

That is:

TraversalVertexProgram + CountMapReduce

Thats stupid. Just use the "reduction" aspects of Memory. Replace CountMapReduce with:

memory.incr("~reducing", traverser.bulk())

Thats it. Likewise for all the other reducing barriers! Now, not only do we don't have to do a MapReduce job, we don't even have to break out of the TraversalVertexProgram (no more "No mid-barrier steps."). Why? Well, because its in memory, its computed on that iteration and then accessible!

g.V().group().by('lang').select('java').values("name")

That would be one TraversalVertexProgram!

.....................why do we even have MapReduce.......................... is Memory all we really need. Crazy.............................................. thats craZy talk................................. but still, think about it.