<i18n dev> Integrated: 8333396: Use StringBuilder internally for java.text.Format.* formatting

[lingjun-cg]

On Mon, 3 Jun 2024 04:18:20 GMT, lingjun-cg <duke at 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.cg at 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