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
Claes Redestad has updated the pull request incrementally with one additional commit since the last revision: Copyrights ------------- Changes: - all: https://git.openjdk.java.net/jdk/pull/6188/files - new: https://git.openjdk.java.net/jdk/pull/6188/files/01fce436..f6adb5b5 Webrevs: - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=6188&range=08 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=6188&range=07-08 Stats: 25 lines in 4 files changed: 22 ins; 0 del; 3 mod Patch: https://git.openjdk.java.net/jdk/pull/6188.diff Fetch: git fetch https://git.openjdk.java.net/jdk pull/6188/head:pull/6188 PR: https://git.openjdk.java.net/jdk/pull/6188