RFR: 8361018: Eliminate unnecessary buffering and encoding conversion in BufferedWriter
Shaojin Wen
swen at openjdk.org
Mon Jun 30 04:54:50 UTC 2025
BufferedWriter -> OutputStreamWriter -> StreamEncoder
In this call chain, BufferedWriter has a char[] buffer, and StreamEncoder has a ByteBuffer. There are two layers of cache here, or the BufferedWriter layer can be removed. And when charset is UTF8, if the content of write(String) is LATIN1, a conversion from LATIN1 to UTF16 and then to LATIN1 will occur here.
LATIN1 -> UTF16 -> UTF8
We can improve BufferedWriter. When the parameter Writer instanceof OutputStreamWriter is passed in, remove the cache and call it directly. In addition, improve write(String) in StreamEncoder to avoid unnecessary encoding conversion.
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Commit messages:
- @Override & non-public
- Update src/java.base/share/classes/java/io/BufferedWriter.java
- final & private inner class
- benchmark parameter charset
- inner class
- only UTF8
- revert PrintStream
- inner class
- inner class
- add benchmark
- ... and 4 more: https://git.openjdk.org/jdk/compare/da7080ff...d40e3d65
Changes: https://git.openjdk.org/jdk/pull/26022/files
Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=26022&range=00
Issue: https://bugs.openjdk.org/browse/JDK-8361018
Stats: 598 lines in 7 files changed: 474 ins; 83 del; 41 mod
Patch: https://git.openjdk.org/jdk/pull/26022.diff
Fetch: git fetch https://git.openjdk.org/jdk.git pull/26022/head:pull/26022
PR: https://git.openjdk.org/jdk/pull/26022
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