BigDecimal is a commonly used class in business development, It is often necessary to perform toString or toPlainString operations on BigDecimal.
The current version uses StringBuilder resulting in multiple memory allocations, I made a modification to improve performance. Because BigDecimal uses stringCache to cache the result of toString, the performance of toString needs special treatment before testing, such as clearing stringCache by unsafe operation before each test, The performance of toString is similar to that of toEngineering. The performance data is as follows: ## 1. benchmark script sh make/devkit/createJMHBundle.sh bash configure --with-jmh=build/jmh/jars make test TEST="micro:java.math.BigDecimals.*ToPlainString" make test TEST="micro:java.math.BigDecimals.*ToEngineering" ## 2. benchmark environment * virtual machine : [aliyun_ecs_c8i.xlarge](https://help.aliyun.com/zh/ecs/user-guide/overview-of-instance-families#c8i) * cpu intel xeon sapphire rapids (x64) ## 3. benchmark result -BigDecimals.testHugeToPlainString avgt 15 188.691 ± 0.822 ns/op (baseline) -BigDecimals.testLargeToPlainString avgt 15 36.656 ± 0.065 ns/op -BigDecimals.testSmallToPlainString avgt 15 34.342 ± 0.068 ns/op -BigDecimals.testToPlainString avgt 15 1719.494 ± 24.886 ns/op +Benchmark Mode Cnt Score Error Units (optimize) +BigDecimals.testHugeToPlainString avgt 15 133.972 ? 0.328 ns/op (+40.84%) +BigDecimals.testLargeToPlainString avgt 15 14.957 ? 0.047 ns/op (145.07%) +BigDecimals.testSmallToPlainString avgt 15 12.045 ? 0.036 ns/op (+185.11) +BigDecimals.testToPlainString avgt 15 1643.500 ? 3.217 ns/op (+4.62%) -Benchmark Mode Cnt Score Error Units (baseline) -BigDecimals.testHugeToEngineeringString avgt 15 207.621 ± 5.018 ns/op -BigDecimals.testLargeToEngineeringString avgt 15 35.658 ± 3.144 ns/op -BigDecimals.testSmallToEngineeringString avgt 15 15.142 ± 0.053 ns/op -BigDecimals.testToEngineeringString avgt 15 1813.959 ± 12.842 ns/op +Benchmark Mode Cnt Score Error Units (optimize) +BigDecimals.testHugeToEngineeringString avgt 15 142.110 ? 0.987 ns/op (+45.09%) +BigDecimals.testLargeToEngineeringString avgt 15 12.509 ? 0.056 ns/op (+185.05%) +BigDecimals.testSmallToEngineeringString avgt 15 10.579 ? 0.066 ns/op (+43.13%) +BigDecimals.testToEngineeringString avgt 15 1646.783 ? 3.060 ns/op (+10.15%) ------------- Commit messages: - update copyright info - optimization for decimal to string Changes: https://git.openjdk.org/jdk/pull/15555/files Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=15555&range=00 Issue: https://bugs.openjdk.org/browse/JDK-8315585 Stats: 748 lines in 4 files changed: 522 ins; 33 del; 193 mod Patch: https://git.openjdk.org/jdk/pull/15555.diff Fetch: git fetch https://git.openjdk.org/jdk.git pull/15555/head:pull/15555 PR: https://git.openjdk.org/jdk/pull/15555
