Systrace
by AweiMC
Systrace is a utility for diagnosing Minecraft mod environments, exporting system thread, Mixin and runtime data with JFR profiling support.
What it does
Systrace inspects the running game and exports what it finds: thread information, the states of Mixins applied by other mods, and details of the runtime environment. It can also run Java Flight Recorder profiling, and the output is formatted to be easier to read. The tool is meant for troubleshooting and performance investigation rather than for changing gameplay.
The mod is available for Fabric, Forge and NeoForge, with files for 1.20.1 and 1.21.1. Either side can run it, and neither needs it, so it can run on a single player's client, on a server, or on both. Systrace is open source under the GNU Affero General Public License v3.0 only, and its source code and issue tracker are publicly linked. The first release was published on 2025-05-20.
Key features
Thread information
Lists the system threads of the running game so their state can be checked during a problem.
Mixin state export
Writes the state of Mixins to a file, which helps when diagnosing conflicts between mods.
Runtime details report
Collects details about the system and runtime that the game is executing on.
JFR profiling
Runs Java Flight Recorder profiling and exports the resulting data for analysis.
Compatibility
Latest build for each game version and loader.
Only full game releases are shown. This mod publishes no snapshot builds.
Use cases
Investigating a crash or slowdown
Exported thread, Mixin and runtime data can be attached to a bug report or examined directly when the game stutters.
Profiling a modpack
JFR profiling data shows where time is spent, which helps when comparing how a large pack behaves before and after a change.
Who it’s for: The mod suits modpack developers, mod authors and server owners who need to see what the running game is doing. Players who only want to play may not need it.
How it compares
Thread from wool is a Fabric-only client and server option for 1.21.8 – 1.21.11, under All rights reserved and not open source, so it targets newer versions than Systrace. Damage Profiling Suite is a Forge-only option for 1.20.1, also under All rights reserved and not open source, and it focuses on damage rather than general thread and Mixin data. STE is published for Forge and NeoForge across 1.20.1 – 1.21.1, under All rights reserved and not open source, and it runs on client and server.
| Mod | Loaders | Game versions | Environment | Updated |
|---|---|---|---|---|
| Systrace | Fabric, Forge and NeoForge | 1.20.1 – 1.21.1 | Client or server, optional | 2025-05-20 |
| Thread from wool | Fabric | 1.21.8 – 1.21.11 | Client and server | 2026-03-21 |
| Damage Profiling Suite | Forge | 1.20.1 | Client and server | 2026-03-07 |
| STE | Forge and NeoForge | 1.20.1 – 1.21.1 | Client and server | 2025-04-04 |
Questions
Which loaders does Systrace support?
Does Systrace have to be installed on the server?
Is Systrace open source?
In the catalog
Systrace is one of 36,990 Utility mods on ModsFinder, and one of 25,772 Utility mods for Fabric. 32,366 mods support Minecraft 1.21.1.
More from AweiMC
Similar mods
What the author says
Supports Fabric, Forge, and NeoForge loaders. Compatible with Minecraft 1.20.1 and 1.21.1. Includes enhanced and readable output formatting. /ste → Export Mixin info, thread states, system environment, and more
Official listing
- Modrinth page
- modrinth.com/mod/systrace
- Owner
- AweiMC
- Published
- 2025-05-20
- Updated on Modrinth
- 2025-05-20
- Facts verified
- 2026-10-15