GeoTIFF reader/writer performance comparison

[Martin Desruisseaux]

Hello all

Apache SIS 1.4 contains a Cloud Optimized GeoTIFF reader, and a GeoTIFF 
writer is currently available in 1.5-SNAPSHOT (not yet fully completed). 
Those reader/writer are in pure Java (ignoring native code provided by 
the JDK itself). There is a widespread belief that a Java code would 
surely be slower than C/C++ code. To verify, we conducted a superficial 
benchmark. It is very superficial in that we tested only one image with 
one compression method, no sub-region, no subsampling, no 
parallelization, no reprojection, etc. But the results nevertheless 
question the above-cited belief. In that benchmark, Apache SIS and GDAL 
performances were equivalent. The numbers actually report Apache SIS as 
very slightly faster than GDAL, but we cannot conclude much because of 
all above-cited limitations, because there is a possibility of biais in 
time measurements (we tried to compensate it), because the differences 
are close to margin errors, and because Apache SIS spent 95% of its time 
in the native code of the `java.util.zip` package. Assuming that GDAL 
also uses the `zlib` library (we did not tested with `libdeflate`), 95% 
of this benchmark is actually measuring the same code. However for the 
remaining 5%, it suggests that the interfacing between Java and the 
native code in `java.nio` and `java.util.zip` packages can be as 
efficient as the interfacing between a C/C++ application and native 
libraries.

More details are there: 
https://www.geomatys.com/2023/10/05/geotiff-reader-writer-performance-comparison/

    Martin