Better Random

Disclaimer

This mod changes RNG, and as such, affects worldgen greatly, so with this mod alone installed vanilla world seeds will no longer be reproducible. If you care about preserving vanilla worldgen parity in your mod pack, refrain from installing this mod.

You were warned.

About the mod

Better Random, or Better PRNG if you prefer, is a mod which replace Minecraft's default Linear congruential generator (LCG for short, used for generating most of random game events, as well as generator used when generating some world features) and Xoroshiro128PlusPlus (used to generate "sequences" aka random generator used for LootPools, as well as generator used when generating most of world features) with a random number generator which have better statistical properties, gjrand.

This mod is virtually incompatible with other mods which mess with vanilla codebase random, such as Faster Random. If you have such mod installed already, decide which mod you will use.

Features:

• Replaces RandomSupport#create, and subsequently, Entity#random, Level#random, worldgen (but not noise map, which means world will have same elevation, but different feature placement), countless other places including mods;
• Patches WorldgenRandom to convert LegacyRandomSource and XoroshiroRandomSource to random provided by Better Random, albeit it may interfere with other mods which deliberately want these random generators to be underlying generators;
• Replaces RandomSequence and RandomSequences with versions which use gjrand;
• Replaces Level#getBlockRandomPos to use Level#random. Previously, getBlockRandomPos utilized LCG with even worse properties than one of Level#random.

Caveats:

• Slime chunk function was patched to be hardwired to LegacyRandomSource so they don't change with this mod installed;
• This mod DOES NOT improve performance, and depending on CPU server is running on, it may actually reduce performance (if JIT compiler can't figure out how to vectorize used PRNG on current processor).

Compatibility:

Should be compatible with everything that doesn't go around public interfaces vanilla code provide. Existing RandomSequence saved data is left untouched (in meaning that nothing is done to it through code, but Minecraft continue to load/create it upon server start), and removing Better Random mid-game won't have any noticeable side effects (but world generation may look weird after installing/removing the mod).