When Python's multiprocessing spawns child processes on macOS (using the
"spawn" method), it also spawns helper processes like the resource tracker
by executing:
./frozen_app -c "from multiprocessing.resource_tracker import main; main()"
A frozen PyInstaller app doesn't understand `-c` natively - it just runs
main(). This causes the resource tracker to fail silently.
This adds a minimal `-c` handler that intercepts the flag, extracts the
inline code, and exec()s it before main() runs. This is required for the
Process() spawn in runner_supervisor.py to work correctly in the DMG.
Note that the pyinstaller docs say `freeze_support` is supposed to make
this work, but it doesn't.
Test plan:
Hardware setup: 3x Mac Studio M3 Ultra connected all-to-all with TB5
- Built a DMG[0].
- Installed on the Macs.
- Started an instance. Got an error this time in ~/.exo/exo.log. The
last DMG from main doesn't show anything when an instance starts, this
now shows the errors.
[0] https://github.com/exo-explore/exo/actions/runs/20464409279/job/58804485197
exo connects all your devices into an AI cluster. Not only does exo enable running models larger than would fit on a single device, but with day-0 support for RDMA over Thunderbolt, makes models run faster as you add more devices.
Features
- Automatic Device Discovery: Devices running exo automatically discover each other - no manual configuration.
- RDMA over Thunderbolt: exo ships with day-0 support for RDMA over Thunderbolt 5, enabling 99% reduction in latency between devices.
- Topology-Aware Auto Parallel: exo figures out the best way to split your model across all available devices based on a realtime view of your device topology. It takes into account device resources and network latency/bandwidth between each link.
- Tensor Parallelism: exo supports sharding models, for up to 1.8x speedup on 2 devices and 3.2x speedup on 4 devices.
- MLX Support: exo uses MLX as an inference backend and MLX distributed for distributed communication.
Benchmarks
Qwen3-235B (8-bit) on 4 × M3 Ultra Mac Studio with Tensor Parallel RDMA
Source: Jeff Geerling: 15 TB VRAM on Mac Studio – RDMA over Thunderbolt 5
DeepSeek v3.1 671B (8-bit) on 4 × M3 Ultra Mac Studio with Tensor Parallel RDMA
Source: Jeff Geerling: 15 TB VRAM on Mac Studio – RDMA over Thunderbolt 5
Kimi K2 Thinking (native 4-bit) on 4 × M3 Ultra Mac Studio with Tensor Parallel RDMA
Source: Jeff Geerling: 15 TB VRAM on Mac Studio – RDMA over Thunderbolt 5
Quick Start
Devices running exo automatically discover each other, without needing any manual configuration. Each device provides an API and a dashboard for interacting with your cluster (runs at http://localhost:52415).
There are two ways to run exo:
Run from Source (Mac & Linux)
Prerequisites:
-
brew (for simple package management on MacOS)
/bin/bash -c "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/HEAD/install.sh)" -
uv (for Python dependency management)
-
macmon (for hardware monitoring on Apple Silicon)
-
node (for building the dashboard)
brew install uv macmon node -
rust (to build Rust bindings, nightly for now)
curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh rustup toolchain install nightly
Clone the repo, build the dashboard, and run exo:
# Clone exo
git clone https://github.com/exo-explore/exo
# Build dashboard
cd exo/dashboard && npm install && npm run build && cd ..
# Run exo
uv run exo
This starts the exo dashboard and API at http://localhost:52415/
macOS App
exo ships a macOS app that runs in the background on your Mac.
The macOS app requires macOS Tahoe 26.2 or later.
Download the latest build here: EXO-latest.dmg.
The app will ask for permission to modify system settings and install a new Network profile. Improvements to this are being worked on.
Using the API
If you prefer to interact with exo via the API, here is an example creating an instance of a small model (mlx-community/Llama-3.2-1B-Instruct-4bit), sending a chat completions request and deleting the instance.
1. Preview instance placements
The /instance/previews endpoint will preview all valid placements for your model.
curl "http://localhost:52415/instance/previews?model_id=llama-3.2-1b"
Sample response:
{
"previews": [
{
"model_id": "mlx-community/Llama-3.2-1B-Instruct-4bit",
"sharding": "Pipeline",
"instance_meta": "MlxRing",
"instance": {...},
"memory_delta_by_node": {"local": 729808896},
"error": null
}
// ...possibly more placements...
]
}
This will return all valid placements for this model. Pick a placement that you like.
To pick the first one, pipe into jq:
curl "http://localhost:52415/instance/previews?model_id=llama-3.2-1b" | jq -c '.previews[] | select(.error == null) | .instance' | head -n1
2. Create a model instance
Send a POST to /instance with your desired placement in the instance field (the full payload must match types as in CreateInstanceParams), which you can copy from step 1:
curl -X POST http://localhost:52415/instance \
-H 'Content-Type: application/json' \
-d '{
"instance": {...}
}'
Sample response:
{
"message": "Command received.",
"command_id": "e9d1a8ab-...."
}
3. Send a chat completion
Now, make a POST to /v1/chat/completions (the same format as OpenAI's API):
curl -N -X POST http://localhost:52415/v1/chat/completions \
-H 'Content-Type: application/json' \
-d '{
"model": "mlx-community/Llama-3.2-1B-Instruct-4bit",
"messages": [
{"role": "user", "content": "What is Llama 3.2 1B?"}
],
"stream": true
}'
4. Delete the instance
When you're done, delete the instance by its ID (find it via /state or /instance endpoints):
curl -X DELETE http://localhost:52415/instance/YOUR_INSTANCE_ID
Other useful API endpoints:*
- List all models:
curl http://localhost:52415/models - Inspect instance IDs and deployment state:
curl http://localhost:52415/state
For further details, see API types and endpoints in src/exo/master/api.py.
Hardware Accelerator Support
On macOS, exo uses the GPU. On Linux, exo currently runs on CPU. We are working on extending hardware accelerator support. If you'd like support for a new hardware platform, please search for an existing feature request and add a thumbs up so we know what hardware is important to the community.
Contributing
See CONTRIBUTING.md for guidelines on how to contribute to exo.
