Ruby meta programming performance In 2015, Pragtob wrote a blog post about Ruby meta programming. Well, you may wonder why I’m talking about a blog that wrote five years ago while the computer science is progressing at ever-increasing speed. I searched for it, because in work we were hit by this problem.
In work we use Cocoapods to manage dependency. In a project with few pods you won’t notice the speed of Cocoapods. But what if, let’s say, 600+ pods? It can take half a minute just for Cocoapods to generate XCode Project files! We managed to narrow down the performance issue to this very Ruby file. On the surface, it’s pretty harmless. There is a helper method that can generate other methods using meta programming, saving the hassle to manually write things like sorting results, memorizing… However, there are also some methods that merely return a constant string but also use this helper. Methods defined using define_method have small overhead, but when the method get called tens of thousands of times, the overhead is big enough to use some monkey patching to optimize it. I monkey patched those methods that use define_method but simply return a constant string. Re-define those methods with plain def resulted in a 5s optimization. 5s may not sound like much, but in programming world, it’s like 3 years!
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