In addition to making new features, I have been fixing bugs related to these new features. There has been a steady trickle of these bugs, some of which have been introduced alongside a new feature, some of which had already existed in an old feature and a couple of which have required upstream fixes in the graph library, Metrics Graphics. One of the latter was quite interesting, so here it is in detail.
One of my colleagues filed a bug about a graph that was displaying some data about the ratio of crashes each day over a couple of weeks. There was a graph and a table that were supposed to be showing the same data, but for some reason they were different. In the table, the ratio of crashes increased dramatically on the 6 August:
But in the graph the spike was on 5 August:
First I tried to reproduce the problem, but when I did, I saw this graph, which agreed with the table:
Our respective graphs were being drawn using the same data, with the dates encoded as the same numbers. So why were they different, and what was so special about me that made the graphs work for me but no-one else?
I’m British, that’s what.
The solution was for Metrics Graphics to offer a new option to convert the time stamps in UTC time instead. So now everyone sees this: