@cl4es made performance optimizations for the simple specifiers of String.format in PR https://github.com/openjdk/jdk/pull/2830. Based on the same idea, I continued to make improvements. I made patterns like %2d %02d also be optimized.
The following are the test results based on MacBookPro M1 Pro: -Benchmark Mode Cnt Score Error Units -StringFormat.complexFormat avgt 15 1862.233 ? 217.479 ns/op -StringFormat.int02Format avgt 15 312.491 ? 26.021 ns/op -StringFormat.intFormat avgt 15 84.432 ? 4.145 ns/op -StringFormat.longFormat avgt 15 87.330 ? 6.111 ns/op -StringFormat.stringFormat avgt 15 63.985 ? 11.366 ns/op -StringFormat.stringIntFormat avgt 15 87.422 ? 0.147 ns/op -StringFormat.widthStringFormat avgt 15 250.740 ? 32.639 ns/op -StringFormat.widthStringIntFormat avgt 15 312.474 ? 16.309 ns/op +Benchmark Mode Cnt Score Error Units +StringFormat.complexFormat avgt 15 740.626 ? 66.671 ns/op (+151.45) +StringFormat.int02Format avgt 15 131.049 ? 0.432 ns/op (+138.46) +StringFormat.intFormat avgt 15 67.229 ? 4.155 ns/op (+25.59) +StringFormat.longFormat avgt 15 66.444 ? 0.614 ns/op (+31.44) +StringFormat.stringFormat avgt 15 62.619 ? 4.652 ns/op (+2.19) +StringFormat.stringIntFormat avgt 15 89.606 ? 13.966 ns/op (-2.44) +StringFormat.widthStringFormat avgt 15 52.462 ? 15.649 ns/op (+377.95) +StringFormat.widthStringIntFormat avgt 15 101.814 ? 3.147 ns/op (+206.91) ------------- Commit messages: - shared between Formatter and FormatProcessor - refactor & bug fix - refactor - bug fix for '%T' not throw error - bug fix - drop the regex code entirely and write a custom parser - fix specifiers duplicate flags not throw error - fix specifiers support '%<s' - parse fast-path support more specifiers - remove unused comment - ... and 6 more: https://git.openjdk.org/jdk/compare/c92bdb0e...59c2983b Changes: https://git.openjdk.org/jdk/pull/15776/files Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=15776&range=00 Issue: https://bugs.openjdk.org/browse/JDK-8316704 Stats: 307 lines in 3 files changed: 272 ins; 14 del; 21 mod Patch: https://git.openjdk.org/jdk/pull/15776.diff Fetch: git fetch https://git.openjdk.org/jdk.git pull/15776/head:pull/15776 PR: https://git.openjdk.org/jdk/pull/15776
