Visualizing Backpressure

This was slightly straight forward than I had hoped. The graphing library is kind of awkward for single bar graphs. Below is a screenshot of what I have so far:

![screen shot 2013-06-10 at 9 02 49 pm](https://f.cloud.github.com/assets/744212/635000/69ff3572-d233-11e2-865c-4eccd2f60b44.png)

Also, I realized there was a small bug in the graphing during the first poll, which is fixed here. My goal is to potentially use some kind of gauge graph, but I think for the time being, a bar is ok.

The backpressure is just the different absolute value of the different between enqueued and processed, if the backpressure is 100 the first poll, and then 500 the next poll, the bar will stay the same height, but the range on the Y-axis will change showing that difference. So the visualization of the load isn't quite accurate. I thought about normalizing the value somehow, but couldn't come up with anything clever. Any ideas?