[vtkusers] vtkUnsignedShortArray GetJavaArray() performance

[Marco Sambin]

Hi all.
I am experiencing some performance issues with the call to
vtkUnsignedShortArray's GetJavaArray() method.

On my PC, this GetJavaArray is taking around 3 milliseconds in case of
a vtkUnsignedShortArray representing a 256x256 image (hence, 65536
elements), while it is taking around 300 milliseconds (!!) in case of
a vtkUnsignedShortArray representing a 512x512 image (hence, 262144
elements).

Is this huge performance difference between 256x256 and 512x512 arrays
to be expected with the GetJavaArray() method?

I understand that here most of the performance penalty may be due to
the Java-to-native crossing related to the JNI mechanism, but why such
a huge difference between the two array sizes?

Thanks in advance for your comments.
Regards,

Marco