No Flamegraph tab or annotations in notebook?

[turbotimon]

I do not see any annotations nor the Flamgraph tab in a Notebook. Any idea why?

Screencast_20251119_112347.webm

However, it works fine with .py files, so it is not a general problem.

--- Flamegraph

Identifier
rafaelha.vscode-flamegraph
Version
0.6.3

--- Vscode

Version: 1.105.1
Commit: 7d842fb85a0275a4a8e4d7e040d2625abbf7f084
Date: 2025-10-14T22:33:36.618Z
Electron: 37.6.0
ElectronBuildId: 12502201
Chromium: 138.0.7204.251
Node.js: 22.19.0
V8: 13.8.258.32-electron.0
OS: Linux x64 6.12.57

[rafaelha]

Could you check if anything shows up in your VSCode terminal? When you click the flame button the extension silently opens a new terminal where it runs a command to attach the profiler. If your terminal is not hidden, you should see that command, and some output that can tell us what went wrong.

[turbotimon]

@rafaelha

 *  Executing task in folder course-dev: "/home/xxx/.venv/bin/py-spy" record --output profile.pyspy --format raw --full-filenames --subprocesses --pid 33245  

source /home/xxx/.venv/bin/activate
Error: No python processes found in process 33245 or any of its subprocesses

 *  The terminal process "/usr/bin/bash '-c', '"/home/xxx/.venv/bin/py-spy" record --output profile.pyspy --format raw --full-filenames --subprocesses --pid 33245 '" terminated with exit code: 1. 
 *  Terminal will be reused by tasks, press any key to close it.

however, pgrep shows:

pgrep python -a
33245 /home/xxx/.venv/bin/python -m ipykernel_launcher -f /home/xxx/.local/share/jupyter/runtime/kernel-32f527e9-407a-4932-8dfc-b543472b298d.json

strange.. Hit me, if you need more info

Some additional infos might be of interest:

• I'm using NixOS (so most hard coded paths e.g for dll fail)
• .venv managed by uv

[rafaelha]

Could you try if enabling this setting helps?

[turbotimon]

@rafaelha sorry for the late reply: both sudo settings are enabled, same error ("Error: No python processes found ..")

But I also see no sudo in the output: The terminal process "/usr/bin/bash '-c', '"/home/xxx/.venv/bin/py-spy" ...

[rafaelha]

Ok - with these options enabled, the terminal command should be run with sudo. Since that's not happening, that's a bug I will fix.

I you want you can try to manually run the command with sudo prepended, i.e. sudo "/home/xxx/.venv/bin/py-spy" record --output profile.pyspy --format raw --full-filenames --subprocesses --pid 33245 (with the appropriate PID of your Jupyter notebook kernel). The extension will automatically open a flamegraph window when a profile.pyspy file is generated by this command.

Let me know if this works, that would be really helpful!

Here is an explanation from the py-spy repo, which I think is why py-spy fails to attach in your case. You can also try setting the ptrace_scope sysctl variable as outlined there.

[turbotimon]

Thanks. I can start it manually (and the terminal waits for input, marked with >, see below):

# in project root: /home/xxx/
pgrep python
#114656 (also in notebook os.getpid() returns the same PID)
sudo "/home/xxx/.venv/bin/py-spy" record --output profile.pyspy --format raw --full-filenames --subprocesses --pid 114656"
> 

However, no profile.pyspy is generated when I execute cells, therefore no windows pops up...

(If i find time i will try it in another distro to check if it is distro specific. However, have very limited time at the moment)

[rafaelha]

For me I get the following command output:

 *  Executing task: sudo "/home/rafaelha/.../.venv/bin/py-spy" record --output profile.pyspy --format raw --full-filenames --nonblocking --pid 2403996  

py-spy> Sampling process 100 times a second. Press Control-C to exit.

^C
py-spy> Stopped sampling because Control-C pressed
py-spy> Wrote raw flamegraph data to 'profile.pyspy'. Samples: 0 Errors: 0
py-spy> You can use the flamegraph.pl script from https://github.com/brendangregg/flamegraph to generate a SVG

The profile.pyspy is only written after manually detaching the profiler with Ctrl+C.

I've tested this on Ubuntu. I'd say don't worry running it on other distros. If the command does not work, that's probably an issue with pyspy and I won't be able to do anything from my side. I'll still look into why the sudo VS Code setting does not add sudo to the commands.