Auto formatting of document+imports racing condition?

Issue Type: Bug

I use the following settings:

  "[python]": {
    "editor.formatOnSave": true,
    "editor.codeActionsOnSave": {
    "source.organizeImports": true
    },
  },
  "python.formatting.provider": "black"

However the imports formatting is very inconsistent. Sometimes it follows black, and most times it doesn’t. Any multi-line imports where each imported variable/function should be on it’s own line (according to black) often isn’t.

If I run Format Document, it formats the imports according to black (one per line):

If I run Organize Imports, it puts everything on as few lines as possible (violates black):

And worst of all, it seems like VSCode is alternating between these two outcomes

1. non-black style
2. non-black style for half a second, then black style.

Since it sometimes work, it seems as if there is a racing condition between the Format Document command and Organize Imports command when both are auto enabled on save in settings. The right thing to do would seem to first run the ordinary import formatting, then run any custom formatting provider afterwards.

Since this looks like a bug / conflict between the “Format Document” and “Organize Imports” commands., which are both build-in, I think this is a VSCode problem, not vscode-python extension problem.

VS Code version: Code - Insiders 1.26.0-insider (573d53815e74f8e4a52c2b6665f5ba9a92dbd341, 2018-08-01T05:17:54.216Z) OS version: Windows_NT x64 10.0.15063

System Info

Item	Value
CPUs	Intel® Core™ i7-6700T CPU @ 2.80GHz (8 x 2808)
GPU Status	2d_canvas: enabled checker_imaging: disabled_off flash_3d: enabled flash_stage3d: enabled flash_stage3d_baseline: enabled gpu_compositing: enabled multiple_raster_threads: enabled_on native_gpu_memory_buffers: disabled_software rasterization: enabled video_decode: enabled video_encode: enabled webgl: enabled webgl2: enabled
Memory (System)	15.88GB (7.09GB free)
Process Argv	C:\Users\s113093\Dropbox\portable-win\VSCode-win32-x64-1.26.0-insider\Code - Insiders.exe
Screen Reader	no
VM	0%

Extensions (33)

Extension	Author (truncated)	Version
Bookmarks	ale	9.0.3
project-manager	ale	8.0.0
spellright	ban	2.5.24
path-intellisense	chr	1.4.2
vscode-svgviewer	css	1.4.4
vscode-markdownlint	Dav	0.19.0
githistory	don	0.4.2
jupyter	don	1.1.4
vscode-pandoc	Dou	0.0.8
gitlens	eam	8.5.4
vsc-material-theme	Equ	2.3.0
prettier-vscode	esb	1.5.0
vscode-diff	fab	1.3.2
latex-workshop	Jam	5.7.0
python	ms-	2018.7.1
PowerShell	ms-	1.8.2
wordcount	ms-	0.1.0
vsliveshare	ms-	0.3.504
gremlins	nho	0.7.0
vscode-docker	Pet	0.1.0
quicktype	qui	12.0.15
vscode-icons	rob	7.24.0
partial-diff	ryu	1.3.0
markdown-preview-enhanced	shd	0.3.5
vscode-spotify	shy	2.5.1
vscode-fileutils	sle	2.10.3
slack	soz	0.0.14
code-spell-checker	str	1.6.10
pdf	tom	0.3.0
vscode-terminal-here	Tyr	0.1.1
vscodeintellicode	Vis	1.0.1
vscode-todo-highlight	way	1.0.4
markdown-all-in-one	yzh	1.6.0

(2 theme extensions excluded)

[brettcannon]

@GandalfSaxe Correct, VS Code doesn’t let us say “please run this before that”. All we get is “sort imports” and “format document” calls and both are done via callbacks which we don’t directly trigger.

[gandalfsaxe]

I’m saying I don’t think it can necessarily be fixed at all. Basically you either need isort to output in a format that black likes (so black no longer care, have black sort imports (so you don’t need isort), or trigger the import sorting manually (so you remove the race condition).

So it’s not possible to say “Sort imports” should finish running before any formatters are allowed to run? VSCode don’t give that capability?

I’ve also followed up on the VS Code issue to try and get more info on how they handle this situation for JavaScript.

Good idea. There could potentially be the same issues between any import organizer they use, and a system like prettier.