<i18n dev> RFR: 8289834: Add SBCS and DBCS Only EBCDIC charsets

[Alan Bateman]

On Mon, 3 Oct 2022 07:14:09 GMT, Ichiroh Takiguchi <itakiguchi at openjdk.org> wrote:

> Test results are as follows on RHEL8.6 x86_64 (Intel Core i7 3520M) :
> 
> ```
> 1.8.0_345-b01
> Benchmark                     Mode  Cnt      Score     Error  Units
> MyBenchmark.testIBM1047      thrpt   25  53213.092 ± 126.962  ops/s
> MyBenchmark.testIBM1047_SPI  thrpt   25  47442.669 ± 349.003  ops/s
> ```
> 
>  ```
> 20-ea+17-1181
> Benchmark                     Mode  Cnt       Score      Error  Units
> MyBenchmark.testIBM1047      thrpt   25  136331.141 ± 1078.481  ops/s
> MyBenchmark.testIBM1047_SPI  thrpt   25   51563.213 ±  843.238  ops/s
> ```
> 
> IBM1047 is 2.6 times faster than the SPI version on JDK20. I think this results are related to **JEP 254: Compact Strings** . As I requested before, we'd like to use `sun.nio.cs.SingleByte*` and `sun.nio.cs.DoubleByte*` class as public API.

I don't think that is a workable option. Maybe you could do more performance analysis on the providers that are using the SPI to see if there are any secure primitives that would make sense to expose in java.nio.charset.spi?  I'm hesitate to suggest adding base classes to java.nio.charset.spi but that may be something that could be exposed too.

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PR: https://git.openjdk.org/jdk/pull/9399