[11u] RFR (XS) 8229022: BufferedReader performance can be improved by using StringBuilder

[Langer, Christoph]

Hi Aleksey,

this looks good to me.

Best regards
Christoph

> -----Original Message-----
> From: jdk-updates-dev <jdk-updates-dev-bounces at openjdk.java.net> On
> Behalf Of Aleksey Shipilev
> Sent: Freitag, 4. Oktober 2019 16:15
> To: jdk-updates-dev at openjdk.java.net
> Subject: [11u] RFR (XS) 8229022: BufferedReader performance can be
> improved by using StringBuilder
> 
> RFE:
>   https://bugs.openjdk.java.net/browse/JDK-8229022
>   https://hg.openjdk.java.net/jdk/jdk/rev/ed0058d06107
> 
> This is a tiny RFE that does substantial performance improvement. The patch
> does not apply cleanly,
> because the context is a bit different. (Mostly because JDK-823042
> LineNumberReader fixes, which I
> have questions about, so it is not really backportable at the moment).
> 
> 11u patch:
> 
> --- old/src/java.base/share/classes/java/io/BufferedReader.java	2019-
> 10-04 16:09:45.826490807 +0200
> +++ new/src/java.base/share/classes/java/io/BufferedReader.java	2019-
> 10-04 16:09:45.674492392 +0200
> @@ -312,7 +312,7 @@
>       * @exception  IOException  If an I/O error occurs
>       */
>      String readLine(boolean ignoreLF) throws IOException {
> -        StringBuffer s = null;
> +        StringBuilder s = null;
>          int startChar;
> 
>          synchronized (lock) {
> @@ -368,7 +368,7 @@
>                  }
> 
>                  if (s == null)
> -                    s = new StringBuffer(defaultExpectedLineLength);
> +                    s = new StringBuilder(defaultExpectedLineLength);
>                  s.append(cb, startChar, i - startChar);
>              }
>          }
> 
> Testing: tier1, tier2
> 
> --
> Thanks,
> -Aleksey