On Fri, Jan 9, 2015 at 4:20 PM, Doug Lea <d...@cs.oswego.edu> wrote: > On 01/09/2015 06:29 PM, Martin Buchholz wrote: > >> Given the prevalence of sub-optimal hashcodes, my own intuition is also >> that >> raising the treeification threshold from 8 will be a win. >> > > That's what I thought at first. But 8 is a better choice for String > and other Comparable keys, which account for the majority of HashMaps > out there. (For non-comparables, infinity is the best threshold.) >
Non-malicious Strings are only rarely going to end up in treebins, because their hash codes are not awful (just sub-optimal - hmmm ... is anyone putting all possible 2-char Strings into a HashMap?). I'm not convinced that comparableClassFor should special-case Strings. Linear search through a non-treebin of non-malicious Strings is likely to be fast, because we will short-circuit if hash codes or length don't match, which compareTo cannot. So compareTo is likely to have more overhead per element, although of course in the end log(N) beats N.
