On Fri, 25 Mar 2022 14:35:46 GMT, Claes Redestad <redes...@openjdk.org> wrote:
>> Richard Startin prompted me to have a look at a case where java.time >> underperforms relative to joda time >> (https://twitter.com/richardstartin/status/1506975932271190017). >> >> It seems the java.time test of his suffer from heavy allocations due >> ZoneOffset::getRules allocating a new ZoneRules object every time and escape >> analysis failing to do the thing in his test. The patch here adds a simple >> specialization so that when creating ZonedDateTimes using a ZoneOffset we >> don't query the rules at all. This removes the risk of extra allocations and >> slightly speeds up ZonedDateTime creation for both ZoneOffset (+14%) and >> ZoneRegion (+5%) even when EA works like it should (the case in the here >> provided microbenchmark). > > Claes Redestad has updated the pull request incrementally with one additional > commit since the last revision: > > Add nanoOfSecond parameter, make micro less reliant on constants src/java.base/share/classes/java/time/ZoneOffset.java line 512: > 510: @Override > 511: /* package-private */ ZoneOffset getOffset(long epochSecond, int > nanoOfSecond) { > 512: return this; An alternate approach would be for `ZoneOffset` to cache the instance of `ZoneRules` either on construction or first use (racy idiom would be OK). That way this issue is solved for the many different places that call `zoneId.getRules()`. ------------- PR: https://git.openjdk.java.net/jdk/pull/7957
