Improvements

Major

First and foremost - testing every single function.
Using a circular buffer that read x BYTES at every cycle rather than readline(). It happen very often that readline() reach EOF before the line have been completly written, thus making corrupted data instead of missing data.

In addition of that, I decided to await for 1sec for each corrupted data to be able to handle slower flow. But this compromise make me output a false hits/sec rate because it reads at most 4000requests per sec (on my machine)
Make more use of the data collected by LogParser because this is both a waste of CPU cycle and time. This is also the goal of this tool.

Using a logging tools to catch error in the app, escpecially for the edge cases of the LogParser.
Create a temporary log file to remember the alert after a crash or a volontary SIGINT.
Improve the design of the interface to make it more user friendly and beautiful
Making a real use of urwid by allowing any user to change threshold real-time on the console.
Make another function to handle apache error log, thus having the possibility to monitor them both at the same time.