On Mon, 28 Jul 2025 17:10:13 GMT, Philippe Marschall <[email protected]> wrote:
>> Use `JavaLangAccess::uncheckedNewStringNoRepl` in `MemorySegment::getString`
>> to avoid byte[] allocation in the String constructor.
>>
>> Fall back to the old code in the case of malformed input to get replacement
>> characters as per Javadoc API specification. The existing tests in
>> `TestStringEncoding` seem sufficient to me.
>>
>> I ran the tier1 test suite and it passes.
>>
>> For performance analysis I ran.
>>
>> make test
>> TEST="micro:org.openjdk.bench.java.lang.foreign.ToJavaStringTest"
>> MICRO="OPTIONS=-prof gc"
>>
>> on an AMD Ryzen 7 PRO 5750GE.
>>
>> These are the formatted results, the current master is the line on top, this
>> feature branch is the line below. We can see an improvement in throughput
>> driven by a reduction in allocation.
>>
>>
>> Benchmark (size) Mode Cnt
>> Score Error Units
>>
>> ToJavaStringTest.panama_readString 5 avgt 30
>> 18.996 ± 0.044 ns/op
>> ToJavaStringTest.panama_readString 5 avgt 30
>> 13.851 ± 0.028 ns/op
>>
>> ToJavaStringTest.panama_readString 20 avgt 30
>> 23.570 ± 0.050 ns/op
>> ToJavaStringTest.panama_readString 20 avgt 30
>> 18.401 ± 0.069 ns/op
>>
>> ToJavaStringTest.panama_readString 100 avgt 30
>> 32.094 ± 0.207 ns/op
>> ToJavaStringTest.panama_readString 100 avgt 30
>> 24.427 ± 0.112 ns/op
>>
>> ToJavaStringTest.panama_readString 200 avgt 30
>> 43.029 ± 0.185 ns/op
>> ToJavaStringTest.panama_readString 200 avgt 30
>> 31.914 ± 0.064 ns/op
>>
>> ToJavaStringTest.panama_readString 451 avgt 30
>> 81.145 ± 0.403 ns/op
>> ToJavaStringTest.panama_readString 451 avgt 30
>> 58.975 ± 0.233 ns/op
>>
>> ToJavaStringTest.panama_readString:gc.alloc.rate.norm 5 avgt 30
>> 72.000 ± 0.001 B/op
>> ToJavaStringTest.panama_readString:gc.alloc.rate.norm 5 avgt 30
>> 48.000 ± 0.001 B/op
>>
>> ToJavaStringTest.panama_readString:gc.alloc.rate.norm 20 avgt 30
>> 104.000 ± 0.001 B/op
>> ToJavaStringTest.panama_readString:gc.alloc.rate.norm 20 avgt 30
>> 64.000 ± 0.001 B/op
>>
>> ToJavaStringTest.panama_readString:gc.alloc.rate.norm 100 avgt 30
>> 264.000 ± 0.001 B/op
>> ToJavaStringTest.panama_readString:gc.alloc.rate.norm 100 avgt 30
>> 144.000 ± 0.0...
>
> Philippe Marschall has updated the pull request incrementally with one
> additional commit since the last revision:
>
> Fix copyright year
The build error was due to a download error
E: Couldn't download
https://httpredir.debian.org/debian/dists/bullseye/main/binary-ppc64el/Packages
Error: Process completed with exit code 1.
-------------
PR Comment: https://git.openjdk.org/jdk/pull/26493#issuecomment-3237165469
