CLJ-1200 - RestFn & ArraySeq performance - HELP REQUESTED

[Alex Miller]

Hey all,

This ticket (http://dev.clojure.org/jira/browse/CLJ-1200) points out a performance hotspot inside ArraySeq (which is also used in several internal scenarios such as rest args). I've spent a fair amount of time analyzing the usage of this class and I've taken the patch a bit further beyond the original.

At this point I am happy with the changes and ready to mark it screened for Rich to check out, however I would really like more feedback on the performance difference. I am looking for:

1) a concise timing example that can be run in a REPL (I do not like the prior example on the ticket due to its erratic behavior)

2) reports from running with this patch on your internal code base. This would involve applying the patch (preferably just this patch) over the clojure 1.5.1 code base and building a custom version of clojure. I suspect those of you in the position to do so know how to do this, but if not, I am happy to help out with that.

3) and of course if someone looks at the patch and disagrees with the changes or finds actual bugs with it, that would of course be good to know. :) 

Thanks,

Alex