AutoSystemGC
by ThatMG393
AutoSystemGC calls System.gc on a schedule or when memory usage crosses a set threshold, freeing memory on a Fabric server or client.
What it does
The mod triggers a garbage collection run through System.gc in two ways: at fixed intervals, measured in seconds, or when used memory reaches a target percentage. Both triggers are set in the config file, which reloads automatically after an edit, so changes take effect without restarting the game. Each cleanup run is written to the log, including the moment it was triggered, which makes it possible to see how often memory was reclaimed.
Setting the scheduled cleanup interval to a value of 30 or lower disables that schedule, and the memory threshold accepts decimal values from 0 to 100. Either side can run it, and neither needs it, so it can be installed on a single-player client, on a dedicated server, or on both. The mod is built for Fabric only and requires Fabric API, which must be installed alongside it.
Files are published for Fabric across 31 release versions, 1.14.4 – 1.21.3, and the latest build targets 1.21.3. The mod is released under All rights reserved and is not open source, though the source code and an issue tracker are publicly linked.
Key features
Scheduled memory cleanup
Runs System.gc at a fixed interval in seconds, and a value of 30 or lower turns the schedule off.
Threshold-based cleanup
Starts a cleanup when used memory passes a target percentage between 0 and 100, with decimal values accepted.
Cleanup logging
Each triggered cleanup is recorded in the log with its details.
Automatic config reload
Edits to the config file are picked up without restarting the game.
Compatibility
Latest build for each game version and loader.
1.21.x4 of 4 versions with builds
1.20.x7 of 7 versions with builds
1.19.x5 of 5 versions with builds
1.18.x3 of 3 versions with builds
1.17.x2 of 2 versions with builds
1.16.x6 of 6 versions with builds
1.15.x3 of 3 versions with builds
1.14.x1 of 1 version with builds
Only full game releases are shown. This mod publishes no snapshot builds.
Requirements
Dependencies declared by the latest file for each loader.
Required 1
Use cases
Who it’s for: Server owners who want memory reclaimed on a schedule, and players who run a client with a tight memory budget and want automatic cleanup. Fabric API must be present on either side.
How it compares
Memory manager is a Fabric mod for 1.20.1, released under the MIT License and open source, that can run on a client or server. Memory Check is a Fabric server-side only mod for 1.19.2 – 26.3 under the GNU General Public License v3.0 only, which is also open source. Scheduled Restart is server-side only, open source under the MIT License and covers 1.15 – 26.2, so it restarts the server on a timer rather than calling the garbage collector.
| Mod | Loaders | Game versions | Environment | Updated |
|---|---|---|---|---|
| AutoSystemGC | Fabric | 1.14.4 – 1.21.3 | Client or server, optional | 2024-11-16 |
| Memory manager | Fabric | 1.20.1 | Client or server, optional | 2024-10-18 |
| Memory Check | Fabric | 1.19.2 – 26.3 | Server-side only | 2026-03-28 |
| Scheduled Restart | Fabric | 1.15 – 26.2 | Server-side only | 2026-03-26 |
Questions
Does AutoSystemGC need Fabric API?
Does the server need the mod?
In the catalog
AutoSystemGC is one of 3,545 Optimization mods on ModsFinder, and one of 2,575 Optimization mods for Fabric. 13,252 mods support Minecraft 1.21.3.
More from ThatMG393
Similar mods
What the author says
Note: > System.gc() just tells the JVM to expend effort toward recycling unused objects. So sometimes System.gc() doesn't free memory.
Official listing
- Modrinth page
- modrinth.com/mod/autosystemgc
- Owner
- ThatMG393
- Published
- 2024-11-15
- Updated on Modrinth
- 2024-11-16
- Facts verified
- 2026-10-15