Codereview request for 7183053: Optimize DoubleByte charset for String.getBytes()/new String(byte[]) (original) (raw)

Xueming Shen xueming.shen at oracle.com
Mon Jul 16 18:42:28 UTC 2012

Hi Alan,

I gave the "continue ->else if " a try, it appears the server vm obviously likes the "continue" approach (it is consistent with what we experienced in the past when we did similar approach for ascii, in which we separate/singled the ascii path out). So I guess we probably want to keep the continue here.

Here are the data. dbcs2_new is to replace the continue with else if and the dbcs2 is the "continue".

http://cr.openjdk.java.net/~sherman/7183053/dbcs2_new http://cr.openjdk.java.net/~sherman/7183053/dbcs2

-Sherman

On 07/13/2012 10:09 AM, Xueming Shen wrote:

In JDK7, the decoder and encoder implementation of most of our single-byte charsets and UTF-8 charset are optimized to implement the internal interfce sun.nio.cs.ArrayDecoder/ Encoder to provide a fastpath for String.getBytes(...) and new String(byte[]...) operations. I have an old blog regarding this optimization at

https://blogs.oracle.com/xuemingshen/entry/fasternewstringbytescs This rfe, as the followup for above changes, is to implement ArrayDe/Encoder for most of the sun.nio.cs.ext.DoubleByte based double-byte charsets. Here is the webrev http://cr.openjdk.java.net/~sherman/7183053/webrev I've taken a pass over this and it's great to see DoubleByte.Decoder/Encoder implementing sun.nio.cs.ArrayDecoder/Encoder. The results looks good too, a small number of regressions (Big5 at len=32 for example) but this is a micro benchmark and I'm sure there are fluctuations. I don't see anything obviously wrong with the EBCDIC changes I'd need a history book to remember how the shifts between DBCS and SBCS. I think our tests our good for this area so I'm happy. One minor nit is the continue in both encode methods, I think it would be cleaner to use "else if (bb ..." instead. The continue might make the vm happy, but this is the code I did last Oct, so I might be wrong. Will give a couple run later with "else"

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