[lisper]

> this is really the only sane option we have

Why?

[wolf550e]

Yeah, I would have gone with BLAKE2. It's much faster than SHA-256 and SHA3-256: https://blake2.net/skylake.png

[benchaney]

This is a perfect example of a situation where hashing performance doesn't matter at all.

[tikhonj]

I'm not familiar with Git internals. Does the performance of the hashing algorithm contribute significantly to how Git deals with large files or with operations over a large number of small files?

I've run into performance problems with things like MathJaX, which includes thousands (or tens of thousands?) of files as a backup method for rendering equations. (I understand each file has a single character in some typeface.)

[harshreality]

The hash function may not matter for overall git performance in virtually all dev machine setups, but there will be a (maybe tiny, maybe larger, depending on the repo and disk io speed) difference in cpu utilization and heat generation, right?

[copperx]

That's a silly thing to worry about when you're developing Ruby or Java applications. My PC boots faster than the Rails console or IntelliJ.

[harshreality]

The broader point is this: code repositories are not the only things git is used for.

[dakull]

JRuby?

[harshreality]

sha3 will probably get hw accel eventually. Blake2 is less likely to. It's like the dilemma between chacha20 and a stream cipher mode for aes. An argument could be made for either, depending on application specifics and available hardware.

[wolf550e]

But like its ancestor chacha, blake2 is fast on anything that has SIMD.