Skip to content
Concept test browser-based debugging of Python Trio applications
Branch: master
Clone or download
Fetching latest commit…
Cannot retrieve the latest commit at this time.
Type Name Latest commit message Commit time
Failed to load latest commit information.

Concept Test: Trio Web Monitor

This module is a hack / concept test for Python Trio monitoring in browser.


Displays in real time all tasks running and where the execution is going, even if the main application is stuck in a busy loop with no scheduling points, or blocked in a synchronous system call.


  • The code is NOT SECURE (no HTML escaping, no auth, probably crashes). Written in a day.
  • Displays last codeline of nursery blocks that have already completed; should notice this state and display a message saying that it is waiting for running tasks even though the body has ended.

Try it

  1. Put somewhere in your program: nursery.start_soon(triowebmon.Monitor().run)
  2. Open http://localhost:8040/ to find out what your code is doing

Debugging for Humans

There are a number of attempts at improving Python and Trio debugging via the use of browser UI. Currently such efforts are quite scattered.

I would like to see some of the above projects unified, as they have similar and overlapping goals, and probably none of the developers involved actually have enough time to maintain these.

One could easily implement killing of any running task by simply clicking on it, or control of Trio clock, step-by-step scheduling and what not.

This project is published only in the hopes that someone might pick up on the idea or benefit of the things I've experimented with (in particular, running a separate thread for the HTTP server, which doesn't seem to crash even when it examines the stack frames running in the main thread).

Please contact me (post an issue here) if you wish to take this development forward in any way.

You can’t perform that action at this time.