On 2/6/20 12:31 PM, Martin Buchholz wrote: > lgtm > > Knuth didn't like linear probing, but memory locality became far more > important over time, favoring linear probing.
(Or variants, like cuckoo, but they are unlikely to be improvements here.) > > I don't get what hash() is doing with the low bits. Maybe we want > something like mix32. It is mainly spreading them upwards because some (varying over time) top bits of identityHashCode are always 0. -Doug > > On Thu, Feb 6, 2020 at 1:01 AM Andrew Haley <a...@redhat.com > <mailto:a...@redhat.com>> wrote: > > On 1/28/20 11:41 PM, Stuart Marks wrote: > > > As an aside, I don't know whether the linear-probing (open > > addressed) arrangement of IdentityHashMap is in fact faster than the > > separate chaining approach of HashMap. Perhaps investigating that > > could be a side project for someone. > > It always has been better in the past, but maybe if the collision rate > is kept low it won't matter much. Deletion is horrible, though. > > > Changeset appended below. > > > > Bug: https://bugs.openjdk.java.net/browse/JDK-8046362 > > OK, thanks. > > -- > Andrew Haley (he/him) > Java Platform Lead Engineer > Red Hat UK Ltd. <https://www.redhat.com> > https://keybase.io/andrewhaley > EAC8 43EB D3EF DB98 CC77 2FAD A5CD 6035 332F A671 >
