On Mon, 24 Nov 2025 08:02:35 GMT, Shaojin Wen <[email protected]> wrote:
> This PR optimizes the parsing performance of DateTimeFormatter by replacing > HashMap with EnumMap in scenarios where the keys are exclusively ChronoField > enum values. > > When parsing date/time strings, DateTimeFormatter creates HashMaps to store > intermediate parsed values. HashMap has more overhead for operations compared > to specialized map implementations. > > Since ChronoField is an enum and all keys in these maps are ChronoField > instances, we can use EnumMap instead, which provides better performance for > enum keys due to its optimized internal structure. > > Parsing scenarios show improvements from 12% to 95% > > - [x] I confirm that I make this contribution in accordance with the [OpenJDK > Interim AI Policy](https://openjdk.org/legal/ai). This pull request has been closed without being integrated. ------------- PR: https://git.openjdk.org/jdk/pull/28471
