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VPython hangs in Jupyter notebook inside VS Code #281
Description
When running VPython inside a Jupyter notebook in VS Code, the code hangs indefinitely.
Minimal working example:
from vpython import *
sphere()Expected behavior:
A 3D canvas should open and display a sphere.
Actual behavior:
The line with sphere() runs forever without producing output. No error message appears.
Environment:
- Python version: 3.12.6
- vpython version: 7.6.5
- jupyterlab-vpython extension version: 3.1.8
- OS: MacOS
- VS Code version: 1.103.2
Additional info:
- The same code works correctly when run as a standalone Python script in VS Code.
- The same code works in Jupyterlab outside of VS Code.
Activity
sspickle commentedon Aug 16, 2026
Two-part answer to this issue is underway:
The silent hang is fixed in Fail loudly instead of hanging forever when no frontend connects (#281) #292:
import vpythonnow fails after 30s with a clear error naming the environment (VS Code detected via its env vars) and pointing at what works, instead of hanging the kernel forever.VPYTHON_CONNECT_TIMEOUTraises the limit for genuinely slow first-runs.Actual VS Code support is being designed: a VS Code extension using the Notebook Renderer API + Jupyter kernel comm messaging (the mechanism ipywidgets uses), rendering through the same host-agnostic
glowcomm_host.jsfrontend recently factored out on thepyodide-packagingbranch (Pyodide/wasm support: pure-Python wheel, worker transport, GlowScript host factory #291). No timeline promised yet, but the hang at least stops being silent now.🤖 Generated with Claude Code
Merge pull request #292 from vpython/fix/281-frontend-connect-timeout
sspickle commentedon Aug 16, 2026
Update: VPython scenes now render live in VS Code notebooks — working prototype, end to end. Objects,
rate()animation, zoom/orbit,text()fonts, and textures all verified.Two pieces:
With the extension absent,
import vpythonfails loudly per #292 instead of hanging. Remote kernels (WSL/SSH/Codespaces) are the main known gap — needs the extension to ask VS Code for port forwarding.fix: compound/text/extrusion/pause deadlock forever in Colab — raise …