> While profiling some code which uses `LineBreakMeasurer`, I noticed that a > non-trivial amount of time was being spent in `AttributedString`, because > iterating through an `AttributedString` and getting a specific attribute for > each character ends up calling `Vector.indexOf` inside of > `AttributedString.getAttribute`. This boils down to the data structure choice > of storing run attribute data in two arrays of `Vector`s, rather than in a > single array of `Map`s. Based on testing, it looks like a single array of > `Map`s would be simpler, faster, and require slightly less memory in some > cases. > > A JMH benchmark is included in this PR. With the updated code I'm seeing a > 35% to 40% reduction in runtime for the iteration benchmark tests with one or > more attributes. I checked memory usage by enabling GC profiling and looking > at the three creation benchmark tests; it seems like there is no difference > when the string has no attributes, a 20% reduction in memory use when the > string has a single attribute, and a very small 1% reduction in memory use > when we set four attributes. Full JMH results below (I focused on the `us/op` > and `B/op` results specifically). > > Tests run: > - make test TEST="jtreg:test/jdk/java/text" > - make test TEST="jtreg:test/jdk/java/awt/font" > - make test TEST="jtreg:test/jdk/java/awt/Graphics2D/DrawString" > - make test TEST="micro:java.text.AttributedStringBench" MICRO="OPTIONS=-prof > gc" > > I've assumed that the existing tests provide adequate regression test > coverage, but there may be other Oracle-internal tests that should also be > run to verify correctness. > > JMH results **before** PR: > > > Benchmark Mode > Cnt Score Error Units > AttributedStringBench.creationWithFourAttributes avgt > 15 0.182 ± 0.004 us/op > AttributedStringBench.creationWithFourAttributes:gc.alloc.rate avgt > 15 3989.259 ± 85.345 MB/sec > AttributedStringBench.creationWithFourAttributes:gc.alloc.rate.norm avgt > 15 760.001 ± 0.001 B/op > AttributedStringBench.creationWithFourAttributes:gc.count avgt > 15 151.000 counts > AttributedStringBench.creationWithFourAttributes:gc.time avgt > 15 116.000 ms > AttributedStringBench.creationWithNoAttributes avgt > 15 0.003 ± 0.001 us/op > AttributedStringBench.creationWithNoAttributes:gc.alloc.rate avgt > 15 10506.090 ± 336.923 MB/sec > AttributedStri...
Daniel Gredler has updated the pull request incrementally with one additional commit since the last revision: Update three comments which mention vectors ------------- Changes: - all: https://git.openjdk.org/jdk/pull/30402/files - new: https://git.openjdk.org/jdk/pull/30402/files/3e9feea0..07e65f70 Webrevs: - full: https://webrevs.openjdk.org/?repo=jdk&pr=30402&range=01 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=30402&range=00-01 Stats: 3 lines in 1 file changed: 0 ins; 0 del; 3 mod Patch: https://git.openjdk.org/jdk/pull/30402.diff Fetch: git fetch https://git.openjdk.org/jdk.git pull/30402/head:pull/30402 PR: https://git.openjdk.org/jdk/pull/30402
