Performance Improvements for Transfer

Last week we had Robin Hilliard of Rocketboots into the office to help us get the biggest bang for our buck performance wise with the Transfer / MachII / ColdSpring application, and I have to say it was a great session all around.

Apart from imparting upon us a great many ideas for aspects of our application we could cache, and various other pearls of wisdom, we turned on Report Execution Times, and managed to find several key places in Transfer that were sometimes called over 500 times in one request (we do a fair amount of data movement per request).

For one thing, in all honesty, I had completely forgotten about Report Execution Times.  I had turned it off when it was making my CFC heavy applications go into a slow paced crawl, and had quite literally left it for dust.

However, after turning it on, and just running it over just a few requests, the key areas of Transfer that would provide significant performance increases became very apparent very quickly.

This is where all those small, finicky, performance 'tricks' come to the fore very quick -

• using else/if statements rather than case statements
• replacing the use of iterators with for() loops that use a counting numeric index
• playing with different Java Collections for different operations - i.e. ArrayList vs LinkedList
• Assigning method results to variables before large looping operations, rather than evaluating them every time.
• ..and other such things

It should be worth noting, that by doing some of these things, the code ended up looking rather ugly, but with testing, performs faster than before.  So this is not to say that I went through the entire Transfer codebase and switched out everything I could find to being the most efficient I could possibly, in fact that couldn't be further from the truth.  There are many places in Transfer that use case statements, even knowing that else/if statements are faster - simply because I find case statements are more readable, and they are not in places of the system that are called in numerous succession.  By the same token, I make extensive use of Java iterators to loop over my collections in Transfer, as they provide a high degree of abstraction away from what sort of Collection is being used behind the scenes, but those places are now limited.  However, by specifically pin pointing aspects of the system that are critical to the performance of the framework, the necessary tweaks to the framework could be discovered and acted upon.

So say thanks for Robin for the new performance improvements for Transfer that can now be found in SVN.