On Fri, 27 Jun 2025 16:48:40 GMT, Shaojin Wen <s...@openjdk.org> wrote:
> 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. Performance test data shows that this PR can significantly improve the performance of BufferedWriter, and can improve the performance by 30%~50% in the write(String) scenario. ## Benchmark Script git remote add wenshao g...@github.com:wenshao/jdk.git git fetch wenshao #baseline git checkout 2758d6ad7767832db004d28f10cc764f33fa438e make make test TEST="micro:java.io.BufferedWriterBench" # current git checkout 13fd490e75ed3ec4be1957e183ab1631c2029c05 make make test TEST="micro:java.io.BufferedWriterBench" ## Benchmark Numbers on MacBook M1 Pro (aarch64) # baseline -Benchmark (charType) (charset) Mode Cnt Score Error Units -BufferedWriterBench.writeCharArray ascii UTF8 avgt 12 2.672 ± 0.097 us/op -BufferedWriterBench.writeCharArray utf8_2_bytes UTF8 avgt 12 22.310 ± 0.150 us/op -BufferedWriterBench.writeCharArray utf8_3_bytes UTF8 avgt 12 21.442 ± 0.097 us/op -BufferedWriterBench.writeCharArray emoji UTF8 avgt 12 34.750 ± 0.245 us/op -BufferedWriterBench.writeString ascii UTF8 avgt 12 2.831 ± 0.078 us/op -BufferedWriterBench.writeString utf8_2_bytes UTF8 avgt 12 22.200 ± 0.102 us/op -BufferedWriterBench.writeString utf8_3_bytes UTF8 avgt 12 21.522 ± 0.132 us/op -BufferedWriterBench.writeString emoji UTF8 avgt 12 34.973 ± 0.331 us/op # current +Benchmark (charType) (charset) Mode Cnt Score Error Units +BufferedWriterBench.writeCharArray ascii UTF8 avgt 12 2.663 ± 0.077 us/op +0.33% +BufferedWriterBench.writeCharArray utf8_2_bytes UTF8 avgt 12 13.807 ± 0.080 us/op +61.58% +BufferedWriterBench.writeCharArray utf8_3_bytes UTF8 avgt 12 16.157 ± 0.230 us/op +32.71% +BufferedWriterBench.writeCharArray emoji UTF8 avgt 12 21.891 ± 0.158 us/op +58.74% +BufferedWriterBench.writeString ascii UTF8 avgt 12 2.125 ± 0.190 us/op +33.22% +BufferedWriterBench.writeString utf8_2_bytes UTF8 avgt 12 14.260 ± 0.716 us/op +55.68% +BufferedWriterBench.writeString utf8_3_bytes UTF8 avgt 12 12.587 ± 0.099 us/op +70.98% +BufferedWriterBench.writeString emoji UTF8 avgt 12 22.810 ± 0.168 us/op +53.32% ------------- PR Comment: https://git.openjdk.org/jdk/pull/26022#issuecomment-3015795787
