Debugger stops working in the middle of a debug session

[sriramgd]

Environment data

• VS Code version: 1.44.0
• Extension version (available under the Extensions sidebar): 2020.3.71659
• OS and version: Darwin x64 19.3.0
• Python version (& distribution if applicable, e.g. Anaconda): Python 3.6.5
• Type of virtual environment used (N/A | venv | virtualenv | conda | ...): virtualenv 16.6.0
• Relevant/affected Python packages and their versions:
• Relevant/affected Python-related VS Code extensions and their versions:
• Jedi or Language Server? (i.e. what is "python.jediEnabled" set to; more info How to update the language server to the latest stable version #3977): Language Server
• Value of the python.languageServer setting: Microsoft

Expected behaviour

Debugging Celery task code which runs within a Django web server process. The celery task_always_eager flag is set, so the code still runs in Django (not in separate Celery process).
Debugger should not stop working during a debug session.

Actual behaviour

Occasionally, but frequently enough, the debugger stops working after stepping through a few steps. The debugger step/continue/run buttons are all enabled, but clicking on them or using shortcuts has no effect, the debugger seems to be stuck on a line of code. The behavior does not seem to have any pattern I can perceive. It occurs at different points on different occasions. Usually when the problem starts, it seems to occur more frequently till I restart VS code, though I am not sure about this.

The + plus to add breakpoints in the watch dropdown of debug tab gets disabled when this condition occurs.

I keep the Raised Exceptions and Uncaught Exceptions checkboxes are unchecked.

This problem re-occurred when I removed all other extensions.

My launch.json is:

{
    "version": "0.2.0",
    "configurations": [
        {
            "name": "Python: Django",
            "type": "python",
            "request": "launch",
            "program": "${workspaceFolder}/manage.py",
            "console": "integratedTerminal",
            "justMyCode": false,
            "pythonPath": "/Users/myusername/git/django-api/virtual_environment/bin/python",
            "args": [
                "runsslserver",
                "--noreload",
                "--nothreading",
                "--certificate",
                "./certs/my-local-server.crt",
                "--key",
                "./certs/my-local-server.key"
            ],
            "django": true
        }
    ]
}

The other log which may be of interest is Output -> log (window). I am not sure if this time coincides with when the particular instance of the problem occurred, but it was at least within a couple of minutes:

[2020-04-10 19:50:04.364] [renderer2] [error] timeout after 1000 ms: Error: timeout after 1000 ms
    at t.RawDebugSession.handleErrorResponse (file:///Applications/Visual Studio Code.app/Contents/Resources/app/out/vs/workbench/workbench.desktop.main.js:3044:67)
    at file:///Applications/Visual Studio Code.app/Contents/Resources/app/out/vs/workbench/workbench.desktop.main.js:3043:339
    at async t.RawDebugSession.shutdown (file:///Applications/Visual Studio Code.app/Contents/Resources/app/out/vs/workbench/workbench.desktop.main.js:3041:336)

Steps to reproduce:

I am not able to create a minimal repro of this. It happens while debugging the project and is not predictable. Let me know if there is anything I can try or generate on my side, which could be helpful.

Logs

Output for Python in the Output panel (View→Output, change the drop-down the upper-right of the Output panel to Python)

User belongs to experiment group 'ShowPlayIcon - start'
User belongs to experiment group 'DebugAdapterFactory - experiment'
User belongs to experiment group 'PtvsdWheels37 - experiment'
User belongs to experiment group 'Reload - experiment'
User belongs to experiment group 'UseTerminalToGetActivatedEnvVars - control'
User belongs to experiment group 'WebHostNotebook - control'
User belongs to experiment group 'LocalZMQKernel - control'
User belongs to experiment group 'CollectLSRequestTiming - experiment'
User belongs to experiment group 'CollectNodeLSRequestTiming - experiment'
User belongs to experiment group 'EnableIPyWidgets - experiment'
> conda --version
> conda info --json
> pyenv root
> python3.7 -c "import sys;print(sys.executable)"
> python3.6 -c "import sys;print(sys.executable)"
> python3 -c "import sys;print(sys.executable)"
> python2 -c "import sys;print(sys.executable)"
> python -c "import sys;print(sys.executable)"
> ~/git/django-api/virtual_environment/bin/python -c "import sys;print(sys.executable)"
> pipenv --version
cwd: ~/git/django-api
> pipenv --version
cwd: ~/git/django-api
> pipenv --venv
cwd: ~/git/django-api
> ~/git/django-api/virtual_environment/bin/python -c "import jupyter"
> ~/git/django-api/virtual_environment/bin/python -c "import jupyter"
> ~/git/django-api/virtual_environment/bin/python -c "import notebook"
> ~/git/django-api/virtual_environment/bin/python -c "import notebook"
> pipenv --venv
cwd: ~/git/django-api
> ~/git/django-api/virtual_environment/bin/python -m jupyter kernelspec --version
> ~/git/django-api/virtual_environment/bin/python -m jupyter kernelspec --version
> pipenv --py
cwd: ~/git/django-api
> pipenv --py
cwd: ~/git/django-api
Starting Microsoft Python language server.
> ~/git/django-api/virtual_environment/bin/python -c "
import unittest
loader = unittest.TestLoader()
suites = loader.discover("./whitemamba", pattern="test*.py")
print("start") #Don't remove this line
for suite in suites._tests:
    for cls in suite._tests:
        try:
            for m in cls._tests:
                print(m.id())
        except:
            pass"
cwd: ~/git/django-api
> ~/git/django-api/virtual_environment/bin/python -c "
import unittest
loader = unittest.TestLoader()
suites = loader.discover("./whitemamba", pattern="test*.py")
print("start") #Don't remove this line
for suite in suites._tests:
    for cls in suite._tests:
        try:
            for m in cls._tests:
                print(m.id())
        except:
            pass"
cwd: ~/git/django-api
> conda --version

Output from Console under the Developer Tools panel (toggle Developer Tools on under Help; turn on source maps to make any tracebacks be useful by running Enable source map support for extension debugging)

Attached in separate file:
[console-devtools.txt](https://github.com/microsoft/vscode-python/files/4463833/console-devtools.txt)

[sriramgd]

One more thing I noticed, the languageServerVersion in package.json is 0.5.30, while the language server version installed on my machine is 0.5.45. The same version keeps getting installed when I delete it from local drive.

[karthiknadig]

Likely microsoft/debugpy#108

[sriramgd]

Thanks @karthiknadig , that is helpful. To add from my side, the problem started occurring a few days (weeks?) back.
Last night in desperation, I went looking for python related settings and among other things turned off

"python.experiments.enabled": false

Have not had the problem since, but was not sure it was this setting or just randomness since I had turned off a few other things and it was only a few hours.

Will report back again in a couple of days.

[sriramgd]

I am quite sure I am past the problem for my local debugging needs. The workaround in my case was turning off the A/B tests setting for the time being.

[int19h]

Yep, all symptoms indicate it's the same thing.