Breakpoint ignored when debugging a cell

[kimadeline]

Testing #141223, followed the steps in microsoft/vscode#131469 to set up Jupyter debugging

Environment: macOS 11.6.2, Python 3.10.1, ipykernel==6.7.0
Jupyter extension version 2022.1.1001744497, VS Code 1.64.0-insider commit f93c696

Tried setting a breakpoint in a cell, and the cell would just get executed normally, the breakpoint was ignored.

The cell:

d = "no"
print(f"What is the value of d? {d}")
d = "yes"
print(f"What is the value of d now? {d}")

Content of the Jupyter output channel after I click on the Debug Cell button:

Info 11:52:11: Executing (status idle) silently Code = import ipykernel\nprint(ipykernel.__version__)
Info 11:52:11: Executing silently Code (completed) = import ipykernel\nprint(ipykernel.__version__)
Info 11:52:12: Executing (status idle) silently Code = import debugpy\ndebugpy.debug_this_thread()
Info 11:52:12: Executing silently Code (completed) = import debugpy\ndebugpy.debug_this_thread()
Info 11:52:12: Execute Cells request 3
Info 11:52:12: Execute Cell 3 ~/Documents/Sandbox/notebooks/notebook.ipynb
Info 11:52:12: Cell 3 executed with state Success
Warn 11:52:12: StdErr from Kernel Process [IPKernelApp] ERROR | Exception in control handler:

Warn 11:52:12: StdErr from Kernel Process Traceback (most recent call last):

Warn 11:52:12: StdErr from Kernel Process   File "/Users/kimiguel/Documents/Sandbox/notebooks/.othervenv/lib/python3.10/site-packages/ipykernel/kernelbase.py", line 281, in process_control

Warn 11:52:12: StdErr from Kernel Process     else:

Warn 11:52:12: StdErr from Kernel Process   File "/Users/kimiguel/Documents/Sandbox/notebooks/.othervenv/lib/python3.10/site-packages/ipykernel/kernelbase.py", line 856, in debug_request

Warn 11:52:12: StdErr from Kernel Process     async def debug_request(self, stream, ident, parent):

Warn 11:52:12: StdErr from Kernel Process   File "/Users/kimiguel/Documents/Sandbox/notebooks/.othervenv/lib/python3.10/site-packages/ipykernel/ipkernel.py", line 426, in do_debug_request

Warn 11:52:12: StdErr from Kernel Process     return await self.debugger.process_request(msg)

Warn 11:52:12: StdErr from Kernel Process   File "/Users/kimiguel/Documents/Sandbox/notebooks/.othervenv/lib/python3.10/site-packages/ipykernel/debugger.py", line 606, in process_request

Warn 11:52:12: StdErr from Kernel Process     elif self.is_started:

Warn 11:52:12: StdErr from Kernel Process   File "/Users/kimiguel/Documents/Sandbox/notebooks/.othervenv/lib/python3.10/site-packages/ipykernel/debugger.py", line 348, in stop

Warn 11:52:12: StdErr from Kernel Process     cleanup_transforms = get_ipython().input_transformer_manager.cleanup_transforms

Warn 11:52:12: StdErr from Kernel Process   File "/Users/kimiguel/Documents/Sandbox/notebooks/.othervenv/lib/python3.10/site-packages/ipykernel/debugger.py", line 232, in disconnect_tcp_socket

Warn 11:52:12: StdErr from Kernel Process     def disconnect_tcp_socket(self):

Warn 11:52:12: StdErr from Kernel Process   File "zmq/backend/cython/socket.pyx", line 640, in zmq.backend.cython.socket.Socket.disconnect

Warn 11:52:12: StdErr from Kernel Process zmq.error.ZMQError: No such file or directory

[rchiodo]

Seems to be caused by Python 3.10 changes. Works with latest IPython/IPykernel if using Python 3.9.

[rchiodo]

Note run by line seems to work fine. It's only Debug Cell that fails (with IPython 8)

[greazer]

I have an environment with IPython 8 and debugging (hitting bps) is working just fine. Turns out that if I set a bp on the first line, then subsequent breakpoints seem to be hit. For example if I have this:

Breakpoints post the first one will be hit:

This would explain why run-by-line continues to work.

[rchiodo]

For me, I had to start debugging twice. Second run and the breakpoints fail to work (ZMQ throws error)

[r3m0t]

I just tried ipykernel's main branch and it works fine.
Looks to be this- ipython/ipykernel#855 as that's the only change since 6.8.0

[danieltomasz]

when switching to Python 3.9.10 breakpoints work ( the rest of env is the same)
Breakpoints also don't work in Jupyter lab when 3.10.2 is in use

[danieltomasz]

this might be related https://youtrack.jetbrains.com/issue/PY-47999
After manual Cython speedups compilation on macOS for Python 3.10 breakpoint are ignored

[danieltomasz]

With the new ipykernel 6.9.0 release, everything seems to work, for 3.10.2 and 3.9.10

[anmolsjoshi]

Experiencing this as well

python 3.9.5
ipykernel == 6.4.1
ipython == 7.29.0
VScode Version: 1.64.1 Commit: d6ee99e4c
Jupyter Extension: v2022.1.1001821375

[Zoxjib]

Experiencing this as well, both in VSCode and also in Jupyter's web UI when attempting to debug .ipynb files.
No issues when debugging .py files.

python 3.10.2
ipykernel == tested on 6.8.0 and 6.9.0
ipython == 8.0.1
VSCode version 1.64.1 Commit: d6ee99e4c
Jupyter Extension: v2022.1.1001821375

I've seen the exact error as reported by the OP, but I've also encountered the following error:

Traceback (most recent call last):
  File "C:\Users\username\AppData\Local\Programs\Python\Python310\lib\runpy.py", line 196, in _run_module_as_main
    return _run_code(code, main_globals, None,
  File "C:\Users\username\AppData\Local\Programs\Python\Python310\lib\runpy.py", line 86, in _run_code
    exec(code, run_globals)
  File "c:\Users\username\.vscode\extensions\ms-python.python-2022.0.1814523869\pythonFiles\lib\python\debugpy\__main__.py", line 45, in <module>
    cli.main()
  File "c:\Users\username\.vscode\extensions\ms-python.python-2022.0.1814523869\pythonFiles\lib\python\debugpy/..\debugpy\server\cli.py", line 444, in main
    run()
  File "c:\Users\username\.vscode\extensions\ms-python.python-2022.0.1814523869\pythonFiles\lib\python\debugpy/..\debugpy\server\cli.py", line 285, in run_file
    runpy.run_path(target_as_str, run_name=compat.force_str("__main__"))
  File "C:\Users\username\AppData\Local\Programs\Python\Python310\lib\runpy.py", line 269, in run_path
    return _run_module_code(code, init_globals, run_name,
  File "C:\Users\username\AppData\Local\Programs\Python\Python310\lib\runpy.py", line 96, in _run_module_code
    _run_code(code, mod_globals, init_globals,
  File "C:\Users\username\AppData\Local\Programs\Python\Python310\lib\runpy.py", line 86, in _run_code
    exec(code, run_globals)
  File "e:\Programming\Github\python\MIT 6.0001\Ses3.ipynb", line 16, in <module>
    "execution_count": null,
NameError: name 'null' is not defined

[danieltomasz]

When creating new environment using code below, debugging works with VERSION=3.9.10 but not with VERSION=3.10.2 (With 3.10.2 will work only when the first line in the cell is debugged as in this issue ipython/ipykernel#841)
I am on macOS 12.3,
Visual Studio 1.64.2,
Jupyter Extension v2022.2.100182281
pyenv 2.2.4

pyenv install 3.10.2
pyenv install 3.9.10
make install VERSION=3.9.10
make install VERSION=3.10.2

Content of the makefile:

.ONESHELL:

.PHONY: install

PROJECT=debug
VERSION?=3.10.2
VENV=${PROJECT}-${VERSION}
VENV_DIR=$(shell pyenv root)/versions/${VENV}
PYTHON=${VENV_DIR}/bin/python

install:
	@echo "Installing $(VENV)"
	pyenv virtualenv ${VERSION} ${VENV}
	pyenv local ${VENV}
	$(PYTHON) -m pip cache purge 
	$(PYTHON) -m pip  install -U pip
	$(PYTHON) -m pip install wheel
	$(PYTHON) -m pip install ipykernel
	$(PYTHON) -m ipykernel install --user --name ${VENV}

[rchiodo]

I think this is debugpy/pydevd's fault. At least it is sent the breakpoints but it doesn't fire them.

[rchiodo]

Logging an issue on debugpy:
microsoft/debugpy#844

[fabioz]

Hi all, this was a change of behavior in Python 3.10 itself (see: https://mail.python.org/archives/list/python-dev@python.org/thread/VXW3TVHVYOMXDQIQBJNZ4BTLXFT4EPQZ/).

I provided a pull request to IPython: ipython/ipython#13535 (still pending).

If anyone wants to try it and is comfortable patching the installed version, you can run in the notebook:

from IPython.core import interactiveshell
print(interactiveshell.__file__)

And then open the file printed and apply the patch from ipython/ipython#13535 (don't forget to restart the notebook afterwards).

p.s.: Given that this issue is an interaction between Python 3.10/ipython/debugpy, I think we can close the issue on vscode-jupyter...

[rchiodo]

Thanks @fabioz

[greazer]

Closing per @fabioz's suggestion.

[fabioz]

As a note, it seems there's another use-case where this happens (with hypothesis: microsoft/debugpy#837), so, I'll provide a bugfix in debugpy itself which will fix both.

[roblourens]

Anything to verify here?

[rchiodo]

I think we have to wait for the fix in ipykernel, so probably no?

[fabioz]

I ended up doing a fix in the debugger itself too (see comments in the PR: microsoft/debugpy#851).

So, this does need a new debugger release...

[johnfkraus]

Can't help but observe a seeming hair trigger for closing issues.