On Mon, 3 Jun 2024 04:18:20 GMT, lingjun-cg <d...@openjdk.org> wrote:
> ### Performance regression of DecimalFormat.format
> From the output of perf, we can see the hottest regions contain atomic
> instructions. But when run with JDK 11, there is no such problem. The reason
> is the removed biased locking.
> The DecimalFormat uses StringBuffer everywhere, and StringBuffer itself
> contains many synchronized methods.
> So I added support for some new methods that accept StringBuilder which is
> lock-free.
>
> ### Benchmark testcase
>
> @BenchmarkMode(Mode.AverageTime)
> @Warmup(iterations = 5, time = 500, timeUnit = TimeUnit.MILLISECONDS)
> @Measurement(iterations = 10, time = 500, timeUnit = TimeUnit.MILLISECONDS)
> @State(Scope.Thread)
> @OutputTimeUnit(TimeUnit.NANOSECONDS)
> public class JmhDecimalFormat {
>
> private DecimalFormat format;
>
> @Setup(Level.Trial)
> public void setup() {
> format = new DecimalFormat("#0.00000");
> }
>
> @Benchmark
> public void testNewAndFormat() throws InterruptedException {
> new DecimalFormat("#0.00000").format(9524234.1236457);
> }
>
> @Benchmark
> public void testNewOnly() throws InterruptedException {
> new DecimalFormat("#0.00000");
> }
>
> @Benchmark
> public void testFormatOnly() throws InterruptedException {
> format.format(9524234.1236457);
> }
> }
>
>
> ### Test result
> #### Current JDK before optimize
>
> Benchmark Mode Cnt Score Error Units
> JmhDecimalFormat.testFormatOnly avgt 50 642.099 ? 1.253 ns/op
> JmhDecimalFormat.testNewAndFormat avgt 50 989.307 ? 3.676 ns/op
> JmhDecimalFormat.testNewOnly avgt 50 303.381 ? 5.252 ns/op
>
>
>
> #### Current JDK after optimize
>
> Benchmark Mode Cnt Score Error Units
> JmhDecimalFormat.testFormatOnly avgt 50 351.499 ? 0.761 ns/op
> JmhDecimalFormat.testNewAndFormat avgt 50 615.145 ? 2.478 ns/op
> JmhDecimalFormat.testNewOnly avgt 50 209.874 ? 9.951 ns/op
>
>
> ### JDK 11
>
> Benchmark Mode Cnt Score Error Units
> JmhDecimalFormat.testFormatOnly avgt 50 364.214 ? 1.191 ns/op
> JmhDecimalFormat.testNewAndFormat avgt 50 658.699 ? 2.311 ns/op
> JmhDecimalFormat.testNewOnly avgt 50 248.300 ? 5.158 ns/op
This pull request has now been integrated.
Changeset: 4da99158
Author: lingjun.cg <lingjun...@alibaba-inc.com>
URL:
https://git.openjdk.org/jdk/commit/4da99158754c25c5d0650f2d042aad3e94a9b0c5
Stats: 765 lines in 16 files changed: 692 ins; 1 del; 72 mod
8333396: Use StringBuilder internally for java.text.Format.* formatting
Reviewed-by: naoto, liach, jlu
-------------
PR: https://git.openjdk.org/jdk/pull/19513
