Raytracing Experience Report

[Ethan McCue]

Hi all,

I have been following along in the "Ray Tracing in a Weekend" book and
trying to make as many classes as possible value classes. (Vec3, Ray, etc.)

https://github.com/bowbahdoe/raytracer

https://raytracing.github.io/books/RayTracingInOneWeekend.html

(without value classes)

time java --enable-preview --class-path build/classes Main > image.ppm


real 4m33.190s
user 4m28.984s
sys 0m5.511s

(with value classes)

time java --enable-preview --class-path build/classes Main > image.ppm


real 3m54.623s
user 3m52.205s
sys 0m2.064s

So by the end the version using value classes beats the version without
them by ~14% using unscientific measurements.

But that is at the end, running the ray tracer on a relatively large scene
with all the features turned on. Before that point there were some
checkpoints where using value classes performed noticeably worse than the
equivalent code sans the value modifier

https://github.com/bowbahdoe/raytracer/tree/no-value-faster

real 1m22.172s
user 1m9.871s
sys 0m12.951s

https://github.com/bowbahdoe/raytracer/tree/with-value-slower

real 3m34.440s
user 3m19.656s
sys 0m14.870s

So for some reason just adding value to the records/classes makes the
program run a over 2x as slow.

https://github.com/bowbahdoe/raytracer/compare/no-value-faster...with-value-slower

Is there some intuition that explains this? I am on a stock M1 Arm Mac.
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