Test Run completion takes very long on many tests (after RunHandler is completed)

[Danielku15]

Type: Performance Issue

Description
I am the author of mocha-vscode and noticed quite significant performance issue when executing a huge number of tests. First I suspected a problem in my extension but realized that my code had already completed and vscode was still performing updates in the UI.

I am executing ~5k tests and Mocha completes within 1-2secs and within my extension the whole RunHandler is completed. But VSCode still takes a significant amount of time to update all status information for the tests and show the log outputs of the extension.

Here a video showing the UI stall and long test execution (despite the RunHandler completed)

vscode-slow.mp4

It look to the user as if the test execution is ongoing and users get this experience:

• They might think the test execution is to blame and attempt cancelling it. But cancelling does nothing in this case.
• The UI is still partly responsive so they might want to check logs which are also frozen.
• They still get test updates, just very slow and they have to wait quite some time for it to finish.

All the calls made to the TestRun to update status information are internally queued and then executed on the UI thread causing delays. If there is anything I could do from my extension I'm happy to change.

**Steps to reproduce: **
Follow the readme in https://github.com/Danielku15/vscode-test-explorer-performance

VS Code version: Code 1.96.3 (91fbddd, 2025-01-09T18:14:09.060Z)
OS version: Windows_NT x64 10.0.26100
Modes:

System Info

Item	Value
CPUs	Intel(R) Core(TM) i7-10700K CPU @ 3.80GHz (16 x 3792)
GPU Status	2d_canvas: enabled canvas_oop_rasterization: enabled_on direct_rendering_display_compositor: disabled_off_ok gpu_compositing: enabled multiple_raster_threads: enabled_on opengl: enabled_on rasterization: enabled raw_draw: disabled_off_ok skia_graphite: disabled_off video_decode: enabled video_encode: enabled vulkan: disabled_off webgl: enabled webgl2: enabled webgpu: enabled webnn: disabled_off
Load (avg)	undefined
Memory (System)	63.92GB (40.60GB free)
Process Argv	--crash-reporter-id 4382a838-d161-4bfb-8e70-abd05b5ada08
Screen Reader	no
VM	0%

Extensions (22)

Extension	Author (truncated)	Version
ng-template	Ang	19.0.4
vscode-eslint	dba	3.0.10
vscode-ast	ddo	0.0.3
vscode-html-css	ecm	2.0.12
prettier-vscode	esb	11.0.0
vscode-github-actions	git	0.27.0
vscode-peacock	joh	4.2.2
csharp	ms-	2.61.28
vscode-dotnet-runtime	ms-	2.2.5
remote-containers	ms-	0.394.0
remote-wsl	ms-	0.88.5
cmake-tools	ms-	1.19.52
cpptools	ms-	1.22.11
cpptools-extension-pack	ms-	1.3.0
extension-test-runner	ms-	0.0.12
hexeditor	ms-	1.11.1
test-adapter-converter	ms-	0.2.1
vetur	oct	0.37.3
markdown-preview-enhanced	shd	0.8.15
cmake	twx	0.0.17
vscode-mdx	uni	1.8.13
vscode-mdx-preview	xyc	0.3.3

(1 theme extensions excluded)

A/B Experiments

vsliv368cf:30146710
vspor879:30202332
vspor708:30202333
vspor363:30204092
vscod805cf:30301675
binariesv615:30325510
vsaa593:30376534
py29gd2263:31024239
c4g48928:30535728
azure-dev_surveyone:30548225
962ge761:30959799
pythonnoceb:30805159
pythonmypyd1:30879173
h48ei257:31000450
pythontbext0:30879054
cppperfnew:31000557
dsvsc020:30976470
pythonait:31006305
dsvsc021:30996838
dvdeprecation:31068756
dwnewjupyter:31046869
nativerepl2:31139839
pythonrstrctxt:31112756
nativeloc1:31192215
cf971741:31144450
iacca1:31171482
notype1cf:31157160
5fd0e150:31155592
dwcopilot:31170013
stablechunks:31184530
6074i472:31201624
dwoutputs:31217127

[vs-code-engineering]

Thanks for creating this issue! It looks like you may be using an old version of VS Code, the latest stable release is 1.96.4. Please try upgrading to the latest version and checking whether this issue remains.

Happy Coding!

[Danielku15]

The problem also exists in the latest version.

Version: 1.96.4 (user setup)
Commit: cd4ee3b1c348a13bafd8f9ad8060705f6d4b9cba
Date: 2025-01-16T00:16:19.038Z
Electron: 32.2.6
ElectronBuildId: 10629634
Chromium: 128.0.6613.186
Node.js: 20.18.1
V8: 12.8.374.38-electron.0
OS: Windows_NT x64 10.0.26100