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

[Shaojin Wen]

On Mon, 25 Sep 2023 11:46:36 GMT, Claes Redestad <redestad 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.

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();
    }
}

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PR Comment: https://git.openjdk.org/jdk/pull/15776#issuecomment-1733597301