On Sat, 6 Jul 2024 00:15:04 GMT, Shaojin Wen <d...@openjdk.org> wrote:
>> String.format is widely used, and improving its performance is very
>> meaningful. This PR can significantly improve the performance of
>> String.format. Sorry, there are many changes, which will take a lot of time.
>> I hope you can review it patiently.
>>
>>
>> Improved performance includes the following:
>>
>> ## 1. Write directly during the parse process to reduce object allocation.
>>
>> In the current Formatter implementation, some objects do not need to be
>> allocated, such as:
>>
>>
>> class Formatter {
>> public Formatter format(Locale l, String format, Object ... args) {
>> List<FormatString> fsa = parse(format);
>> // ...
>> }
>>
>> static List<FormatString> parse(String s) {
>> ArrayList<FormatString> al = new ArrayList<>();
>>
>> while (i < max) {
>> int n = s.indexOf('%', i);
>> if (n < 0) {
>> //
>> al.add(new FixedString(s, i, max));
>> }
>> }
>> }
>> }
>>
>> In the process of parsing, the content that is not a Specifier is directly
>> appended without going through FixedString. By directly printing the parsed
>> FormatString object, there is no need to construct a `List<FormatString>
>> fsa` to store it.
>>
>> ## 2. Fast path print
>> Use specialized FormatString implementations for single-character and
>> single-width specifiers to avoid calling the large FormatSpecifier#print
>> method.
>>
>> ## 3. String.format directly calls j.u.Formatter
>> String.format directly calls j.u.Formatter via SharedSecrets to improve
>> performance
>
> Shaojin Wen has updated the pull request incrementally with one additional
> commit since the last revision:
>
> Implementing JavaUtilFormatterAccess using anonymous class
This PR has a lot of changes, which is a lot of work for review, but it can
significantly improve the performance of most String.format scenarios.
String.format is widely used, so it is meaningful.
Can someone help me review and finish it? Thanks
@cl4es @liach
-------------
PR Comment: https://git.openjdk.org/jdk/pull/20055#issuecomment-2240562362
