On Tue, 18 Jun 2024 10:00:33 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
>
> lingjun-cg has updated the pull request incrementally with one additional
> commit since the last revision:
>
> 8333396: Performance regression of DecimalFormat.format
> If not that, throw a StackOverflowException when run with
> DecimalFormat.format(double)
I'm not sure I understand this point.
I think this is on the right track and looks much better with the generic
implementation.
src/java.base/share/classes/java/text/ChoiceFormat.java line 561:
> 559: toAppendTo.append(choiceFormats[i]);
> 560: } catch (IOException ioe) {
> 561: throw new UncheckedIOException(ioe.getMessage(), ioe);
Perhaps `AssertionError` instead of `UncheckedIOException` is better suited
here and in the other ocurrences.
src/java.base/share/classes/java/text/Format.java line 278:
> 276: * {@code false} otherwise
> 277: */
> 278: boolean isInternalSubclass() {
Since this is defined in Format, can we apply similar changes of StringBuilder
formatting to the other Format subclasses beyond just NumberFormat.
For example, in DateFormat, something such as,
<T extends Appendable & CharSequence> T formatWithGeneric(Date date,
T toAppendTo,
FieldPosition pos) {
throw new UnsupportedOperationException("Subclasses should override
this method");
}
-------------
PR Review: https://git.openjdk.org/jdk/pull/19513#pullrequestreview-2126447188
PR Review Comment: https://git.openjdk.org/jdk/pull/19513#discussion_r1645029030
PR Review Comment: https://git.openjdk.org/jdk/pull/19513#discussion_r1645026453
