Speeding up Rails startup time

Wish I could vote for this to be in 1.9.3 as easily as I can vote for it on HN.

Couple things:

* Wow, an O(n^2) require algo. I guess this really drives home that we shouldn't make basic assumptions about the quality of the libs we use without actually looking at them. Great catch.

* For all of you waiting for this to be pulled into Ruby master. Why not just patch your copy in the meantime?

He reduced the example in the post to the core of the issue, which is the time complexity O(n) for each load (thus O(n^2) overall), and his replacing the existing data structure with what seems (I didn't look at the patch for very long) like a hash[1] which should be O(1) for each load (O(n) overall). A tradeoff of speed for some additional memory.

There is quite a bit going on in module loading. I think reducing it to 'ass clowns' is a bit unwarranted.

[1]: publicly exposed as an array, but a hash internally for actual loading and checking to see if loaded already.

edit: fixed bigO notation

Given the roots in Perl, which has the %INC hash, it's surprising that Ruby started with an array for loaded modules. Can anyone shed some light on this design decision? Surely there was a reason at some point -- and maybe there still is.

Does this problem exist in jruby and rubinius as well?