On Thu, 9 Feb 2023 13:46:14 GMT, Per Minborg <[email protected]> wrote:
>> `ZoneOffset` instances are cached by the `ZoneOffset` class itself for
>> values in the range [-18h, 18h] for each second that is on an even quarter
>> of an hour (i.e. at most 2*18*4+1 = 145 values).
>>
>> Instead of using a `ConcurrentHashMap` for caching instanced, we could
>> instead use an `AtomicReferenceArray` with direct slot value access for said
>> even seconds. This will improve performance and reduce the number of object
>> even though the backing array will go from an initial 32 in the CHM to an
>> initial/final 145 in the ARA. The CHM will contain much more objects and
>> array slots for typical numbers of entries in the cache and will compute
>> hash/bucket/collision on the hot code path for each cache access.
>
> Per Minborg has updated the pull request incrementally with three additional
> commits since the last revision:
>
> - Remove unused setup method
> - Rename method in test
> - Add copyright header
src/java.base/share/classes/java/time/ZoneOffset.java line 451:
> 449: ZoneOffset newValue = new ZoneOffset(totalSeconds);
> 450: ID_CACHE.putIfAbsent(newValue.getId(), newValue);
> 451: return newValue;
Suggestion:
ZoneOffset existing = ID_CACHE.putIfAbsent(newValue.getId(),
newValue);
return existing == null ? newValue : existing;
-------------
PR Review Comment: https://git.openjdk.org/jdk/pull/12346#discussion_r1171288185
