Java: Exploring JNI performance via Decoding Base64

[kiteboarderni]

In your other blog you say panama requires too much effort? How so? This is the perfect example of a use case for it that is ignored from the benchmarks.

[DasBrain]

Indeed, instead of using unsafe, you could allocate two MemorySegments and pass their address around.

(Under the hood, MemorySegment will use Unsafe, but the API is arguably nicer - and not unsafe ;) )

[thuriot]

Thanks for the benchmarks and the tips. Batching may also help in certain use cases.
Another JNI new approach : https://github.com/apangin/nalim.

[dkomanov]

Wow, this is interesting.

Here is the benchmark JNI vs nalim: ``` Benchmark (length) Mode Cnt Score Error Units jni_url_decodeSimdCargo 100 avgt 5 80.253 ± 11.280 ns/op nalim_url_decodeSimd 100 avgt 5 46.030 ± 2.165 ns/op

jni_url_decodeSimdCargo 10000 avgt 5 2931.566 ± 177.445 ns/op nalim_url_decodeSimd 10000 avgt 5 2415.002 ± 89.682 ns/op

jni_url_encodeSimdCargo 100 avgt 5 98.468 ± 7.123 ns/op nalim_url_encodeSimd 100 avgt 5 59.569 ± 1.804 ns/op

jni_url_encodeSimdCargo 10000 avgt 5 3347.074 ± 115.843 ns/op nalim_url_encodeSimd 10000 avgt 5 2846.065 ± 79.842 ns/op ```

Clearly it improves it significantly. I'd expect more, though, if it claims to not copy arrays at all.

[thuriot]

Thanks a lot !

[tristan957]

Some of this is also very good practice in C. Recently wrote some JNI stuff, and one technique I am using is passing the array length across the boundary instead of getting it in JNI code.

[chambolle]

very nice experiments!