Previewing large diff prevents diffing other files for about 10-20 seconds

[borekb]

• VSCode Version: 1.26.1
• OS Version: macOS High Sierra, Windows 10

Steps to Reproduce:

1. Have a version-controlled project with a large file, for example, yarn.lock or package-lock.json are usually good suspects to reproduce this.
2. Make some change in that large file, e.g., install new npm dependency.
3. Make some other, "normal" change to some source file so that you have two changes to commit.
4. In the VCS sidebar, click the large file (e.g., yarn.lock) – VSCode opens the diff editor.
5. Click the other file, notice that the much smaller diff is not being opened for quite a while (can be somewhere between 10-20 seconds on my machine).

VSCode is responsive during this time but clicking files in the VCS panel does nothing, or appears to. I've been observing this issue for many versions of VSCode and finally decided to report it :)

Does this issue occur when all extensions are disabled?: Yes

[alexdima]

Duplicate of #40681

[alexdima]

@borekb Can you please give the files that reproduce or some files very similar in shape (if you cannot share the original files) ?

[borekb]

@alexandrudima I just found out that it's most likely caused by some extension as I can't reproduce it in Insiders. Good luck to me finding out which one it is as I have quite a few of them:

My VSCode stable extensions:

Extension	Author (truncated)	Version
spellright	ban	2.5.32
emojisense	bie	0.4.1
markdown-preview-github-styles	bie	0.1.3
vscode-tailwindcss	bra	0.1.11
npm-intellisense	chr	1.3.0
path-intellisense	chr	1.4.2
vscode-markdownlint	Dav	0.20.0
githistory	don	0.4.2
gitlens	eam	8.5.6
remotehub	eam	0.2.0
EditorConfig	Edi	0.12.4
tslint	eg2	1.0.39
vscode-npm-script	eg2	0.3.5
LogFileHighlighter	emi	2.4.1
markdown-table-formatter	fcr	1.3.2
php-debug	fel	1.12.5
auto-rename-tag	for	0.0.15
vscode-pull-request-github	Git	0.1.5
rest-client	hum	0.19.1
crane	Hvy	0.3.8
vscode-github	Kni	0.30.0
goto-last-edit-location	kri	0.2.1
git-tree-compare	let	1.3.0
terraform	mau	1.3.4
dotenv	mik	1.0.1
vscode-docker	Pet	0.2.0
code-settings-sync	Sha	3.1.2
vscode-scss-formatter	Sib	1.0.2
vscode-markdown-link-suggestions	Tom	11.0.1
vscode-terminal-here	Tyr	0.1.1
es-quotes	vil	0.2.6
quokka-vscode	Wal	1.0.148
wallaby-vscode	Wal	1.0.93
markdown-all-in-one	yzh	1.6.0

My Insiders extensions:

Extension	Author (truncated)	Version
markdown-preview-github-styles	bie	0.1.3
vscode-markdownlint	Dav	0.20.0
gitlens	eam	8.5.6
EditorConfig	Edi	0.12.4
code-settings-sync	Sha	3.1.2
vscode-markdown-link-suggestions	Tom	11.0.1
markdown-all-in-one	yzh	1.6.1

[alexdima]

@borekb This is pretty easy to figure out. Just run F1 > Show running extensions and press the record button. You might need to restart in order to run the extension host with debugging turned on.

Then, do the steps that reproduce for you and the extension with the most CPU time will show up. You can also save the profile if you want to and attach it here.

[borekb]

Thanks, I'll try that.

[borekb]

Hmm, after reproducing the behavior and running profiler at the same time, this is the result after roughly 10 seconds. I.e., "nothing":

VSCode is perfectly responsive at all time, I just hear CPU fan spinning faster and clicking on other files in SCM view does nothing.

Any other suggestions on where to look?

[alexdima]

@borekb Can you please save the profile and attach it here. Sometimes, we have trouble automatically associating a certain stack trace to a certain extension and sometimes we need to look into the profile manually.

Also, it is possible that extensions include native node modules. In such cases, we could not associate the CPU time spent directly.

Btw, if the above list reproduces for you, you might want to look into disabling: EditorConfig (unlikely), Spell Right, emojisense of Path Intellisense, as they are 3rd party extensions.

[borekb]

Will do. By the way, I have many more extensions as shown in #57697 (comment), the screenshot is a small part of it.

[alexdima]

One way I would approach this would be to open VS Code and do the minimal steps necessary to reproduce. From your extension list, it looks like you opened markdown files, JSON files and TS/JS files before reproducing. Every time you do something, it is more likely more extensions get activated and begin to do something ...

[vscodebot]

This issue has been closed automatically because it needs more information and has not had recent activity. See also our issue reporting guidelines.

Happy Coding!

[borekb]

@alexandrudima Hi, he're a profile of the following situation: no tabs open, only two files changed in SCM panel: package.json and yarn.lock. I started profiling, clicked yarn.lock, seen the diff open, clicked pakcage.json, it did not open so I stopped profiling and exported this file:

CPU-20180926T065255.265Z.cpuprofile.txt

[borekb]

BTW, I see the same behavior not only in the SCM panel but also e.g. with the Git Tree Compare extension which also opens diffs.

[alexdima]

@borekb In the CPU profile you have attached, there is a lot of CPU usage in a method named getGitProviderOwnerAndRepositoryFromGitConfig. Almost like it is called in a loop or something:

After searching for the long method name on GitHub, I had a hit here

So it would be best to reach out to @KnisterPeter and create an issue directly at https://github.com/KnisterPeter/vscode-github .

[borekb]

@alexandrudima Thanks! Will do.