flake8 process is causing very high CPU ussage

[paw-lu]

Environment data

• VS Code version: 1.41.1
• Extension version (available under the Extensions sidebar): 2020.1.58038
• OS and version: macOS 10.14.4
• Python version (& distribution if applicable, e.g. Anaconda): 3.5.6
• Type of virtual environment used (N/A | venv | virtualenv | conda | ...): venv
• Relevant/affected Python packages and their versions:
  • flake8==3.7.9
  • flake8-bugbear==20.1.3
  • flake8-docstrings==1.5.0
  • flake8-isort==2.8.0
  • flake8-mypy==17.8.0
  • flake8-rst-docstrings==0.0.13
  • pyflakes==2.1.1
• 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): Jedi

Expected behaviour

Linting will not cause CPU usage to spike

Actual behaviour

Process python -m flake8 --format=%(row)d,%(col)d,%(code).1s,%(code)s:%(text)s from VS code is using showing 100% CPU usage.

I see that this user was having the same issues, but created an issue in the wrong repo microsoft/vscode#88351

Steps to reproduce:

[NOTE: Self-contained, minimal reproducing code samples are extremely helpful and will expedite addressing your issue]

Currently opening any Python file causes this to occur. Closing the python files will not terminate the process. Only closing VS code will.

In settings "python.linting.flake8Enabled": true,.

The following is the used .flake8 file

[flake8]
ignore = E203, E266, E501, W503
max-line-length = 80
max-complexity = 18
docstring-convention = numpy
select = B,C,E,F,W,B9,D,RST

Logs

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

[Info] Looking for git repository
[Info] Git repository found, initializing review manager and pr tree view.
[Info] Review> Validate state in progress
[Info] Review> Validating state...
[Info] No remote with name 'upstream' found. Please update your 'githubPullRequests.remotes' setting.
[Info] No remote with name 'upstream' found. Please update your 'githubPullRequests.remotes' setting.
[Info] Found GitHub remote
[Info] Found GitHub remote
[Info] Review> Queuing additional validate state
[Info] Review> no matching pull request metadata found for current branch plotting-stypes
[Info] Review> Validating state...
[Info] No remote with name 'upstream' found. Please update your 'githubPullRequests.remotes' setting.
[Info] Found GitHub remote
[Info] Review> no matching pull request metadata found for current branch plotting-stypes

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)

[Extension Host] Info Python Extension: 2020-01-31 09:43:27: > ~/Documents/pyfrb_projects/pyfrb/pyfrb_env/bin/python -m flake8 --format=%(row)d,%(col)d,%(code).1s,%(code)s:%(text)s ~/Documents/pyfrb_projects/pyfrb/pyfrb/__init__.py

[paw-lu]

I was able to narrow this down a bit more. This only occurs on .py files that have type hints, such as:

def sum(x: int, y:int) -> int:
    return x + y

Apparently, this is caused by the flake8-mypy extension. While the local .flake8 does not enable any of the flake8-mypy warnings, I do have a global ~/.config/flake8 that reads

[flake8]
ignore = E203, E266, E501, W503
max-line-length = 80
max-complexity = 18
docstring-convention = numpy
select = B,C,E,F,W,T4,B9,D,BLK,I0,RST,PD,N8
mypy_config = /Users/pcosta/.config/mypy.ini

This set up causes flake8 to hang when being called to check on a file with type hints. This seems like a flake8-mypy issue mostly, and does not concern the vscode-python team.

I think the VS code issue is that this process continues to run even after you close the .py file in the editor, and only terminates once VS Code is closed for good. So I'd like to amend the issue:

---

Expected behavior

flake8 processes terminate once all Python files are closed.

Actual behavior

Even after .py files are closed, the flake8 process will continue running. This becomes an issue when there are flake8 bugs/quirks and large amounts of resources are consumed in the background.

[ericsnowcurrently]

@pscosta5, thanks for letting us know about this. We'll get back to you as soon as we can.

[paw-lu]

Thanks for the update @ericsnowcurrently !

[ericsnowcurrently]

The behavior you want sound reasonable. 😄 We consider it a feature request and will look at how well the change fits in to our plans. Thanks!