Yesterday (March 16th) I celebrated my 47th birthday. I am now packing a solid 20 years of work experience and a masters degree in computer science. Still I managed to screw up bad.
A potential customer of mine, who is currently evaluating FlexGanttFX for their application, contacted me and argued that the initial model creation takes too long. 22 seconds to be precise. I asked them to send me a standalone demo and when I ran it I could confirm that it takes a long time to create the model. After further investigation I realized that they were creating over 5 million objects (activities that will be placed on the timeline). All of these objects are then inserted into a balanced binary interval tree. When I saw that I basically told them to stop evaluating FlexGanttFX because it will not be able to handle these many objects and that object creation and the tree modifications do take their time. So the basic message I sent was “Go somewhere else. Fu.. off!”.
However, they also included a snapshot of the profiler they used and I could see that most of the time was spent inside the constructor of the base model class “ActivityBase” and not inside the tree modifications (which I found surprising). After some more research I realized that it was primarily the creation of the activity ID, which is of type String and uses UUID.randomUUID(). So I replaced this logic with a simple counter of type Long. After this change the total time went from 22 seconds to 8. Nice! But it got even better.
To be on the safe side I made sure that the start and end times of my activities are initialized with Instant.now(). However, there was no need for that as those times are usually passed to the activity in the constructor or after creation by calling setStart/EndTime(). After this change the total loading time went down to 7 seconds.
Since the problem at hand was to create a lot of objects very fast I decided to change the initial heap size allocated to the program to 2 Gigabytes. This brought down the loading time to 2 seconds.
From 22 seconds to 2 after 10 minutes of work, not bad! However, quite embarrassing considering the initial “Fu.. off!” 🙂