Memory Leak Fix modern port

By
Noobyboom

Fixes multiple memory leaks in Minecraft, both client-side and server-side

Memory Leak Fix — Forge Port for Minecraft 1.20.1

Fixes multiple memory leaks in Minecraft, both client-side and server-side.

The original Memory Leak Fix (38.8M downloads, FX) bundled a set of small fixes for known vanilla memory leaks. This is an unofficial Forge port for Minecraft 1.20.1, built and verified in CI via GitHub Actions, including a headless runtime test.

What it does (ported fixes)

Biome temperature cache — shares one static ThreadLocal temperature cache instead of one per Biome instance (the original's non-static ThreadLocal created a cache per biome).
Texture resource buffer (MC-226729) — frees the off-heap ByteBuffer allocated by TextureUtil.readResource when reading a texture fails part-way.
Crosshair target clear — clears Minecraft.crosshairPickEntity and hitResult at the start of each client tick so stale targets do not pin entities between frames.

Per-fix status (original → 1.20.1 Forge)

Original fix	1.20.1 status
Biome temperature ThreadLocal	Ported (`BiomeThreadLocalMixin`)
TagKey interner leak (MC-248621)	Not ported — `TagKey` was rewritten in 1.20.1 (its static interner shape changed), so the original's `<clinit>` redirector has no target; the fix is not applicable to 1.20.1
TextureUtil free buffer (MC-226729)	Ported (`TextureUtilFreeBufferMixin`, `require = 0` so texture-internals drift can never break loading)
Target entity clear	Ported; injects at head of `runTick(boolean)` since `updateScreenAndTick` takes a `Screen` in 1.20.1 (`MinecraftTargetClearMixin`)
Entity memories leak (MC-260605)	Not ported — vanilla fixed it in 1.19.4 (per the original's own notes); the Brain/Entity/LivingEntity mixins would be no-ops
Drowned navigation leak (MC-202246)	Not ported — original targeted 1.16.3–1.16.5 only; its `Drowned` navigation fields no longer exist in 1.20.1
Huge screenshot leak	Not ported — it needs MixinExtras local capture, which is not bundled in this Forge port; the method target also changed shape in 1.20.1

Port changes vs. the original

Forge @Mod entrypoint, mods.toml, and a plain-Mixin setup (MixinExtras was not bundled; the ported mixins were rewritten with plain @Redirect/@Inject and compile against official Mojang mappings for 1.20.1).
Mixin config: memoryleakfix.mixins.json (minVersion 0.8, JAVA_17, refmap), pack.mcmeta pack_format 15.

Installation

Install Forge 47.4.20 for Minecraft 1.20.1
Drop memoryleakfix-1.20.1-forge-*.jar into your mods folder

Original mod & credit

This is an unofficial Forge port by Itamio of Memory Leak Fix by FX (PR0CESS).

Original mod: https://modrinth.com/mod/memoryleakfix
Original source: https://github.com/fxmorin/memoryLeakFix
Leak explanations: https://github.com/fxmorin/memoryLeakFix/wiki/Current-Fixes
License: LGPL-2.1-only — see LICENSE

All credit for the original concept, design, and logic goes to FX. See NOTICE.