At my present job , Most of the time, I have to do changes in the legacy Java code to improve performance.
But this time i was asked to tell the extent of performance improvement due to my changes . I tried to use some Java Profiler , I tried Eclipse TPTP and HPROF but due to complacency of the legacy application. I was not able to profile my changes.
So i decided to keep it simple . Log the timestamps and analyze the result. But the log generated by this was unable to show any subsequent improvement in performance as I had to log time in Milliseconds ( System.nanoTime () could not be used for Java 1.4) .
For better time precesion i googled and found this timer library by Vladimir Roubstov.I tweaked it for my code and got the comprehesive log output.
Now to analyze the log, I wrote a python script that reads two log files and generates the time improvements in aggregation and for each run. This was the most exciting part.
for i in imap(lambda x,y:(x, y, x-y), [float(b) for b in new_list],[float(a) for a in old_list]): print '%f - %f = %f' % i
I wrote it in no time , Python Rocks . Then I decided to go one step further. What about plotting it on a graph. Straight away Google Chart API came to my mind and there is python wrapper to this.
So I wrote this small function to produce graph for these logs.
def draw_chart(): from pygooglechart import Axis,SimpleLineChart chart = SimpleLineChart(600,200, x_range=(0.000, 0.999), y_range=(0.000, 0.999)) chart.set_colours(['ff0000', '0000ff']) chart.set_legend(['New','Old']) chart.add_data([float(a) for a in old_list]) chart.add_data([float(b) for b in new_list]) chart.set_axis_range(Axis.LEFT, 0.000, 0.999) chart.set_axis_range(Axis.BOTTOM, 1, 100) chart.download('D:\\my_data.png')
This is the graph generated for my data :
The graph does not show much improvement though , but the post was about joys of python and APIs :)
P.S. : There are Java backports for using 1.5 > features like System.nanoTime().