On Mon, 1 Nov 2021 13:04:20 GMT, Claes Redestad <redestad@openjdk.org> wrote:
Prompted by a request from Volkan Yazıcı I took a look at why the java.time formatters are less efficient for some common patterns than custom formatters in apache-commons and log4j. This patch reduces the gap, without having looked at the third party implementations.
When printing times: - Avoid turning integral values into `String`s before appending them to the buffer - Specialize `appendFraction` for `NANO_OF_SECOND` to avoid use of `BigDecimal`
This means a speed-up and reduction in allocations when formatting almost any date or time pattern, and especially so when including sub-second parts (`S-SSSSSSSSS`).
Much of the remaining overhead can be traced to the need to create a `DateTimePrintContext` and adjusting `Instant`s into a `ZonedDateTime` internally. We could likely also win performance by specializing some common patterns.
Testing: tier1-3
This pull request has now been integrated. Changeset: ce8c7670 Author: Claes Redestad <redestad@openjdk.org> URL: https://git.openjdk.java.net/jdk/commit/ce8c76700ba854f43c48d32b068b30e7d78d... Stats: 564 lines in 4 files changed: 533 ins; 12 del; 19 mod 8276220: Reduce excessive allocations in DateTimeFormatter Reviewed-by: scolebourne, naoto ------------- PR: https://git.openjdk.java.net/jdk/pull/6188