RFR: 8316704: Regex-free parsing of Formatter and FormatProcessor specifiers

[Raffaello Giulietti]

On Mon, 25 Sep 2023 12:20:36 GMT, Shaojin Wen <duke at openjdk.org> wrote:

>>> The reason why I split it into multiple small methods is to avoid a single method codeSize > 325. After merging small methods, the performance will decrease.
>> 
>> Yes, I can refactor to keep the same structure and verify performance is neutral or better. I can pick that up as a low-priority follow-up if you don't mind.
>
>> > The reason why I split it into multiple small methods is to avoid a single method codeSize > 325. After merging small methods, the performance will decrease.
>> 
>> Yes, I can refactor to keep the same structure and verify performance is neutral or better. I can pick that up as a low-priority follow-up if you don't mind.
> 
> Thank you very much for your very patient review. I will be happy to see you make improvements. I see no slowdown in JMH, but I see slowdowns when I run the loop directly in the code. I am also confused. It may be that codeSize > 325 cannot be inline, which will cause some scenes to be slower.
> 
> 
> import org.openjdk.jmh.infra.Blackhole;
> 
> public class StringFormatBench {
>     public static String s = "str";
>     public static int i = 17;
>     public static long l = 1234567L;
>     public static float f = 123.37f;
> 
>     public void complexFormat(Blackhole bh) {
>         bh.consume("%3s %10d %4S %04X %4S %04X %4S %04X".formatted(s, i, s, i, s, i, s, i));
>     }
> }
> 
> public class StringFormatBenchTest {
>    public static void complexFormat() throws Throwable {
>         for (int j = 0; j < 5; j++) {
>             long start = System.currentTimeMillis();
>             for (int i = 0; i < 10_000_000; ++i) {
>                 benchmark.complexFormat(BH);
>             }
>             long millis = System.currentTimeMillis() - start;
>             System.out.println("StringFormatBench-complexFormat millis : " + millis);
>             // zulu8.58.0.13 :
>             // zulu11.52.13 :
>             // zulu17.38.21 :
>             // jdk22-ea : 4644
>             // jdk22-baseline :  16040
>         }
>     }
> 
>     public static void main(String[] args) throws Throwable {
>         complexFormat();
>     }
> }

@wenshao Can we consider the code in `FormatSpecifierParser` stable enough for a thorough review, or do you plan to make other changes there?

-------------

PR Comment: https://git.openjdk.org/jdk/pull/15776#issuecomment-1737325308