RFR: 8325730: StringBuilder.toString allocation for the empty String [v2]

[Aleksey Shipilev]

On Tue, 20 Feb 2024 18:04:18 GMT, Claes Redestad <redestad at openjdk.org> wrote:

>> src/java.base/share/classes/java/lang/StringBuilder.java line 478:
>> 
>>> 476:         }
>>> 477:         // Create a copy, don't share the array
>>> 478:         return new String(this, null);
>> 
>> Ok, this got me a bit confused, but I think this just inlines the call to this constructor:
>> 
>> 
>>     public String(StringBuilder builder) {
>>         this(builder, null);
>>     }
>
> Yes, I was mostly reaching for increased consistency with `StringBuffer` here.

Good then, thanks.

>> test/micro/org/openjdk/bench/java/lang/StringBuilderToString.java line 33:
>> 
>>> 31: import org.openjdk.jmh.annotations.Param;
>>> 32: import org.openjdk.jmh.annotations.Scope;
>>> 33: import org.openjdk.jmh.annotations.Setup;
>> 
>> Is this needed?
>
> It's needed again now that I reverted the code removals.. :-)

Mhm. I don't see any new `@Setup` methods anywhere. Just checked out the PR locally, removed this import and benchmarks still build, and `StringBuilderToString` bench still runs. Am I missing something here?

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PR Review Comment: https://git.openjdk.org/jdk/pull/17931#discussion_r1496297773
PR Review Comment: https://git.openjdk.org/jdk/pull/17931#discussion_r1496315384