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Dimension Leak Fix

Dimension Leak Fix

Fixes memory leaks when switching dimensions. Mods like Collective, AmbientSounds and Create retain old worlds in RAM - this mod cleans them up automatically, recovering 2-4 GB per transition.

83
1

Compatibility

Minecraft: Java Edition

1.21.x
1.20.x
1.19.x
1.18.2

Platforms

Creators

Bahanos
BahanosMember

Details

Licensed ARR
Published 20 hours ago
Updated 3 weeks ago

Every time you travel between the Overworld, Nether, and End, your client creates a new ClientWorld. The old world should be garbage-collected, but several popular mods accidentally hold references to it - causing it to stay in memory forever.

After just a few dimension changes, this can eat 4-8 GB of RAM, leading to lag spikes, stuttering, and eventually crashes.

Dimension Leak Fix automatically detects dimension transitions and surgically breaks these retention chains, recovering 2-4 GB of memory per transition.

What it fixes

Source Problem Impact
Entity references Entities in the old world hold a .level field pointing back to it ~200 MB per transition
Collective BlockEntityData.cachedBlockEntities retains old worlds through nested WeakHashMaps ~1.2 GB per transition
AmbientSounds AirPocketScanner thread holds thousands of ChunkSections as a GC root ~1.4 GB per transition
Create Renderer caches hold references to old world data Variable
Chunk storage Old world's ChunkManager retains all loaded chunks in memory ~1-3 GB per transition

How it works

The mod uses a two-phase approach:

  • Phase A (instant): When you change dimension, the mod immediately detaches entity references, flushes Collective caches, stops the AmbientSounds scanner thread, detaches Spark command senders, and invalidates Create's renderer.
  • Phase B (3 seconds later): The mod clears the old world's chunk storage array and entity sets. This is delayed to avoid interfering with the renderer during the transition.

Compatibility

  • Client-side only - does not need to be installed on the server
  • Works with or without any of the mods listed above - the mod detects what's installed and only applies relevant fixes
  • Tested with 200+ mods including Iris, Sodium, Distant Horizons, Create, Collective, AmbientSounds

Log output

The mod logs everything it does. Example output after a dimension change:

[DimensionLeakFix] Dimension change detected, cleaning up old world...
[DimensionLeakFix]   Entities: 131 world references detached
[DimensionLeakFix]   Collective: 1 cache(s) flushed in cachedBlockEntities
[DimensionLeakFix]   AmbientSounds: scanner stopped (3 fields cleared)
[DimensionLeakFix]   Create: renderer cache invalidated
[DimensionLeakFix] Phase A complete (137 operations)
[DimensionLeakFix] Phase B scheduled (3s delay)
[DimensionLeakFix] Phase B: releasing old world data...
[DimensionLeakFix]   Chunks: 2809 slots released
[DimensionLeakFix]   loadedChunks: 2809 entries cleared
[DimensionLeakFix] Phase B complete (2810 references released, ~3706 MB freed)

Used in the Legends Reborn: Medieval modpack.