Last January a challenge was posted online by Gunnar Morling:
How fast can you parse a file with one billion rows of weather data using Java?
Little did I know this deceivingly simple question would lead me down a path that taught me all about: parallelism, memory mapped files, SWAR techniques (SIMD as a register), bit twiddling, branchless code, mechanical sympathy, Graal native compilation and finally... I even turned to the dark side: using sun.misc.Unsafe.
Join me in this deep dive where I'll explain all the code changes and tricks that took me from the reference implementation which processes the billion records in less than 4 minutes, to processing everything in under two seconds.
Who knew Java could be this fast?