fileWatcher at 100% CPU

[Jason3S]

Type: Performance Issue

fileWatcher process oftens gets stuck at 100% CPU.

It seems to be SCM related, but hard to tell.

VS Code version: Code 1.92.2 (Universal) (fee1edb, 2024-08-14T17:29:30.058Z)
OS version: Darwin x64 23.6.0
Modes:

System Info

Item	Value
CPUs	Intel(R) Core(TM) i9-9880H CPU @ 2.30GHz (16 x 2300)
GPU Status	2d_canvas: enabled canvas_oop_rasterization: disabled_off 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 webgl: enabled webgl2: enabled webgpu: enabled webnn: disabled_off
Load (avg)	5, 4, 4
Memory (System)	32.00GB (4.10GB free)
Process Argv	--crash-reporter-id 21ae0ece-62a2-4681-a5cf-c687ea23e753
Screen Reader	no
VM	0%

Process Info

CPU %	Mem MB	   PID	Process
   19	   262	   838	code main
    8	    98	  2931	   gpu-process
    0	     0	  2940	   utility-network-service
    0	   164	  4942	shared-process
    0	     0	 99421	     /bin/ps -ax -o pid=,ppid=,pcpu=,pmem=,command=
    0	    33	  4944	ptyHost
    0	     0	  5774	     /bin/zsh -il
    0	    33	  6283	       node
    0	     0	  6678	     /bin/zsh -il
    0	     0	 32740	     /bin/zsh -il
    0	     0	 33276	     /bin/zsh -il
    0	    33	 34358	       npm run watch
    0	    33	 34382	         node /Users/jason/projects/vscode-spell-checker/node_modules/.bin/concurrently npm:watch:esbuild npm:watch:api npm:watch:tsc
    0	    33	 34385	           npm run watch:esbuild
    0	    33	 34457	             npm run build:esbuild --watch
    0	    33	 34572	               node ./build.mjs --watch
   13	   197	 34613	                 /Users/jason/projects/vscode-spell-checker/node_modules/@esbuild/darwin-x64/bin/esbuild --service=0.23.1 --ping
    0	    33	 34387	           npm run watch:tsc
    0	    33	 34488	             npm run build:tsc --watch
    0	   328	 34611	               node /Users/jason/projects/vscode-spell-checker/node_modules/.bin/tsc -p tsconfig.test.json --watch
    0	     0	 74824	     /bin/zsh -il
    5	  1049	 74656	window [15] (urlUtil.test.mts — Spell Checker (Workspace))
   99	    66	 74822	fileWatcher [15]
    0	  1769	 74823	extensionHost [15]
    0	   229	 75316	     PHP Language Server
    0	    66	 75552	     electron-nodejs (server-node.js )
    0	   164	 75725	     /Applications/Visual Studio Code.app/Contents/Frameworks/Code Helper (Plugin).app/Contents/MacOS/Code Helper (Plugin) /Users/jason/.vscode/extensions/streetsidesoftware.code-spell-checker-4.0.10/packages/_server/dist/main.cjs --node-ipc --clientProcessId=74823
    0	   164	 80839	     electron-nodejs (eslintServer.js )
    0	   328	 80849	     electron-nodejs (tsserver.js )
    0	   754	 80850	     electron-nodejs (tsserver.js )
    0	    98	 80888	       electron-nodejs (typingsInstaller.js typesMap.js )
    0	   197	 80870	     electron-nodejs (server.js )
    0	    98	 80872	     /Applications/Visual Studio Code.app/Contents/Frameworks/Code Helper (Plugin).app/Contents/MacOS/Code Helper (Plugin) /Users/jason/.vscode/extensions/streetsidesoftware.code-spell-checker-4.0.10/packages/_serverPatternMatcher/dist/main.cjs --node-ipc --clientProcessId=74823
    0	    98	 80873	     mdx-language-server
    2	    66	 99339	window [22] (Issue Reporter)

Workspace Info

|  Window (urlUtil.test.mts — Spell Checker (Workspace))
|    Folder (vscode-spell-checker): 6395 files
|      File types: map(1278) mts(785) json(541) mjs(379) log(375) ts(372)
|                  js(345) md(136) png(110) svg(106)
|      Conf files: package.json(118) tsconfig.json(16) github-actions(14)
|                  settings.json(11) launch.json(6) tasks.json(3)
|                  jsconfig.json(1)
|      Launch Configs: extensionHost(9)
|    Folder (client): 1742 files
|      File types: map(656) mts(439) ts(217) mjs(147) js(76) json(23) md(6)
|                  txt(5) png(4) jsonc(3)
|      Conf files: package.json(4) launch.json(1) settings.json(1)
|                  tasks.json(1) tsconfig.json(1)
|    Folder (_server): 979 files
|      File types: map(406) mts(270) mjs(183) ts(33) js(22) json(14) snap(4)
|                  md(3) txt(2) cjs(2)
|      Conf files: launch.json(1) settings.json(1) tasks.json(1)
|                  package.json(1) tsconfig.json(1)
|      Launch Configs: node
|    Folder (_serverPatternMatcher): 57 files
|      File types: map(15) mts(10) json(8) mjs(7) ts(3) md(2) cjs(2)
|                  gitignore(1) txt(1) cts(1)
|      Conf files: launch.json(1) settings.json(1) tasks.json(1)
|                  package.json(1) tsconfig.json(1)
|      Launch Configs: node
|    Folder (_integrationTests): 36 files
|      File types: json(8) md(7) mts(6) txt(2) gitignore(1) cts(1) yaml(1)
|      Conf files: package.json(2) settings.json(1) tsconfig.json(1)
|    Folder (__utils): 185 files
|      File types: map(68) mts(48) mjs(23) ts(22) js(11) json(3) tgz(1)
|                  snap(1)
|      Conf files: package.json(1) tsconfig.json(1)
|    Folder (build-tools): 23 files
|      File types: ts(6) map(6) js(4) json(3) md(1)
|      Conf files: package.json(1) tsconfig.json(1)
|    Folder (utils-disposables): 76 files
|      File types: map(30) ts(15) js(10) cjs(5) cts(5) json(4) md(1)
|      Conf files: package.json(1) tsconfig.json(1)
|    Folder (utils-logger): 38 files
|      File types: map(12) ts(6) js(4) json(4) mts(2) mjs(2) tsbuildinfo(2)
|                  md(1)
|      Conf files: package.json(1) tsconfig.json(1)
|    Folder (json-rpc-api): 57 files
|      File types: map(18) ts(12) js(6) json(5) mts(3) mjs(3) tsbuildinfo(2)
|                  md(1)
|      Conf files: tsconfig.json(2) package.json(1)
|    Folder (webview-api): 55 files
|      File types: ts(18) map(18) js(9) json(2) snap(2)
|      Conf files: package.json(1) tsconfig.json(1)
|    Folder (webview-rpc): 96 files
|      File types: map(36) ts(18) js(12) mts(6) mjs(6) json(4) tsbuildinfo(2)
|                  md(1)
|      Conf files: package.json(1) tsconfig.json(1)
|    Folder (webview-ui): 37 files
|      File types: svelte(10) ts(6) json(2) css(2) js(2) gitignore(1) md(1)
|                  yaml(1) ttf(1) map(1)
|      Conf files: package.json(1) tsconfig.json(1)
|    Folder (docs): 137 files
|      File types: js(39) html(19) md(16) png(16) json(6) xml(3) svg(3) txt(2)
|                  mjs(2) ico(2)
|      Conf files: package.json(2) settings.json(1) jsconfig.json(1)
|    Folder (website): 207 files
|      File types: json(47) js(43) html(18) md(11) svg(10) png(8) mjs(3)
|                  css(3) xml(3) txt(2)
|      Conf files: package.json(1) tsconfig.json(1);

Extensions (93)

Extension	Author (truncated)	Version
terraform	4op	0.2.5
ada	Ada	24.0.6
commit-message-editor	ada	0.25.0
tsl-problem-matcher	amo	0.6.2
alignment	ann	0.3.0
cpupro	ant	0.1.1
vscode-zipfs	arc	3.0.0
astro-vscode	ast	2.14.1
npm-intellisense	chr	1.4.5
jison-syntax-highlight	cru	0.1.1
scala	dal	0.0.5
vscode-jq-playground	dav	4.3.5
vscode-eslint	dba	3.0.13
vscode-wasm	dts	1.4.1
gitlens	eam	15.3.0
EditorConfig	Edi	0.16.4
prettier-vscode	esb	11.0.0
linter-gfortran	for	3.2.0
copilot	Git	1.223.0
copilot-chat	Git	0.18.2
remotehub	Git	0.62.0
vscode-github-actions	git	0.26.3
vscode-pull-request-github	Git	0.94.0
gitpod-desktop	git	0.0.172
yaml-plus-json	hil	1.12.2
mediawiki	jak	2.1.0
latex-workshop	Jam	10.1.0
svg	joc	1.5.4
jq-syntax-highlighting	jq-	0.0.2
vscode-tree-sitter-query	jri	0.0.6
language-haskell	jus	3.6.0
vscode-cfml	Kam	0.5.4
bison	lun	0.1.0
Kotlin	mat	1.7.1
Lisp	mat	0.1.12
rainbow-csv	mec	3.12.0
dotenv	mik	1.0.1
vscode-apache	mrm	1.2.0
vscode-puglint	mrm	2.3.0
vscode-azureresourcegroups	ms-	0.9.2
vscode-docker	ms-	1.29.2
vscode-dotnet-runtime	ms-	2.1.2
al	ms-	13.1.1065068
playwright	ms-	1.1.7
black-formatter	ms-	2024.2.0
debugpy	ms-	2024.10.0
isort	ms-	2023.10.1
python	ms-	2024.12.3
vscode-pylance	ms-	2024.8.1
jupyter	ms-	2024.7.0
jupyter-keymap	ms-	1.1.2
jupyter-renderers	ms-	1.0.19
vscode-jupyter-cell-tags	ms-	0.1.9
vscode-jupyter-slideshow	ms-	0.1.6
remote-containers	ms-	0.380.0
remote-ssh	ms-	0.113.1
remote-ssh-edit	ms-	0.86.0
remote-wsl	ms-	0.88.2
azure-account	ms-	0.12.0
azure-repos	ms-	0.38.0
cpptools	ms-	1.21.6
cpptools-extension-pack	ms-	1.3.0
live-server	ms-	0.4.14
powershell	ms-	2024.2.2
remote-explorer	ms-	0.4.3
remote-repositories	ms-	0.40.0
test-adapter-converter	ms-	0.1.9
vscode-js-profile-flame	ms-	1.0.9
vsliveshare	ms-	1.0.5936
vetur	oct	0.37.3
common-lisp	qin	1.2.11
vscode-yaml	red	1.15.0
rust-analyzer	rus	0.3.2078
es6-mocha-snippets	spo	0.2.2
avro	str	0.5.0
code-spell-checker	str	4.0.10
code-spell-checker-british-english	str	1.4.11
code-spell-checker-portuguese	str	2.0.2
code-spell-checker-portuguese-brazilian	str	2.2.1
hunspell	str	1.0.4
iconfont-preview	stx	0.0.5
svelte-vscode	sve	108.6.0
even-better-toml	tam	0.19.2
msbuild-project-tools	tin	0.6.5
es6-string-html	Tob	2.16.0
vscode-mdx	uni	1.8.10
intellicode-api-usage-examples	Vis	0.2.8
vscodeintellicode	Vis	1.3.1
vscode-gradle	vsc	3.16.4
vscode-java-debug	vsc	0.58.0
debug	web	0.27.0
php-debug	xde	1.35.0
php-intellisense	zob	1.3.3

(1 theme extensions excluded)

A/B Experiments

vsliv368:30146709
vspor879:30202332
vspor708:30202333
vspor363:30204092
vscod805:30301674
binariesv615:30325510
vsaa593:30376534
py29gd2263:31024239
vscaac:30438847
c4g48928:30535728
azure-dev_surveyone:30548225
vscrp:30673768
2i9eh265:30646982
962ge761:30959799
pythongtdpath:30769146
welcomedialogc:30910334
pythonnoceb:30805159
asynctok:30898717
pythonregdiag2:30936856
pythonmypyd1:30879173
2e7ec940:31000449
pythontbext0:30879054
accentitlementsc:30995553
dsvsc016:30899300
dsvsc017:30899301
dsvsc018:30899302
cppperfnew:31000557
dsvsc020:30976470
pythonait:31006305
dsvsc021:30996838
945dj816:31013170
pythoncenvpt:31062603
a69g1124:31058053
dvdeprecation:31068756
dwnewjupyter:31046869
impr_priority:31102340
refactort:31108082
pythonrstrctxt:31112756
wkspc-onlycs-c:31111717
wkspc-ranged-c:31118571

It is hard to say if it is related, but copilot tends to get stuck after killing the watcher.

[Jason3S]

A bit more information:

• Restarting the Extension Host doesn't seem to make a difference. The fileWatcher still runs at 100%.
• Sometimes there is more than one fileWatcher process running. But only 1 seems to get stuck at 100%.
• Killing the fileWatcher process using Process Explorer seems to help, but the issue often comes back a few minutes later.
• Restarting VSCode helps for longer.
• Note: I tend to keep VSCode open for days.
• The issue is intermittent.
• Seems to happen more often when debugging a VSCode Extension.
• Started happening about 2 months ago.

[bpasero]

Does it go away if you set typescript.tsserver.experimental.useVsCodeWatcher to false.

And can you share a repository where this happens easy to reproduce?

[Jason3S]

@bpasero,

Thank you.

It is not easy to reproduce.

Here is the repo: https://github.com/streetsidesoftware/vscode-spell-checker

Setup is:

npm install
npm run build

Does it go away if you set typescript.tsserver.experimental.useVsCodeWatcher to false.

I will try it out. It might be related, since it seem to happen quicker if I do a bit of refactoring or delete node_modules and rebuild.

[bpasero]

Thank you.

[balazsbajorics]

I had a similar problem with the fileWatcher pinning a CPU to 100%, and indeed setting typescript.tsserver.experimental.useVsCodeWatcher to false fixed it for me!

the repository is https://github.com/concrete-utopia/utopia, working inside the editor folder has been making the filewatcher spin on 100% for weeks now.

[Jason3S]

I had a similar problem with the fileWatcher pinning a CPU to 100%, and indeed setting typescript.tsserver.experimental.useVsCodeWatcher to false fixed it for me!

the repository is https://github.com/concrete-utopia/utopia, working inside the editor folder has been making the filewatcher spin on 100% for weeks now.

@balazsbajorics,

Thank you for the repo case.

I hadn't found a good case in my own repos to properly test it out.

[bpasero]

@balazsbajorics thanks, I tried to repro (on macOS) but do not see that. Is there a build step involved (maybe PNPM?) to get this into that state?

When I set log level to trace and open the file watcher output channel, I only see a small amount of recursively watched folders, maybe you could check too:

[File Watcher] request stats:

[Summary]
- Recursive Requests:     total: 125, suspended: 118, polling: 3
- Non-Recursive Requests: total: 1339, suspended: 3, polling: 0
- Recursive Watchers:     total: 7, active: 7, failed: 0, stopped: 0
- Non-Recursive Watchers: total: 1336, active: 6, failed: 7, reusing: 1323
- I/O Handles Impact:     total: 16
- ```

[bpasero]

ℹ I would appreciate if people impacted here could try out our latest insiders build (commit c4efe1dc9eec4914f3076b2d954fe4fe174a5820). It includes a change to reduce the pressure of file watching from the TypeScript extension.

Steps:

• download insiders from https://code.visualstudio.com/insiders/
• configure typescript.tsserver.experimental.useVsCodeWatcher to the default value of true
• please make sure your files.watcherExclude setting does not include **/node_modules/*/**
• perform your workload that was showing issues

Happy to hear back how it goes 🙏

[tmm1]

hi @bpasero, i have been tracking this issue as well (albeit in a vscode 1.91.1 fork), and I have reason to believe this would be fixed by upgrading:

vscode/package.json

Line 77 in 7eae20c

"@parcel/watcher": "2.1.0",

to v2.3.0 or newer, to include: parcel-bundler/watcher#146

when this happened to me earlier, I attached Instruments.app (and after loading the associated v29.4.0 electron dSYMs), saw the following:

it appears to be stuck in this loop:

https://github.com/libuv/libuv/blob/32603fd5ff56ea4634c66ce2941a053f5d381edd/src/unix/async.c#L197-L202

  while (!uv__queue_empty(&queue)) {
    q = uv__queue_head(&queue);
    h = uv__queue_data(q, uv_async_t, queue);


    uv__queue_remove(q);
    uv__queue_insert_tail(&loop->async_handles, q);

this makes little sense, and could only happen if something massively got corrupted in the linked list somehow.

on the libuv side, things have been stable for quite a while. there are some old issues that describe possibly-related behavior:

• on windows, there was mention of uv_send_async from a nodejs extension causing weird behavior in the early days of electron Electron hangs and leads to 100% CPU usage after calling callback via uv_async_send on a single-core machine electron/electron#11699
• unix: remove busy loop from uv_async_send libuv/libuv#3879
• unix: fix race condition in uv_async_send() libuv/libuv#2231

nothing directly confirming my theory in these old threads.. but if a process running nothing but the watcher.node ext is causing uv to loop, removing the calls into libuv from that extension may help?

[tmm1]

The easiest way to diagnose this is using /usr/bin/sample <fileWatcherPid>. If you have the correct version of the electron dSYMs downloaded and extracted, it will produce accurate call traces as so:

Call graph:
    2094 Thread_8903082   DispatchQueue_1: com.apple.main-thread  (serial)
    + 2094 start  (in dyld) + 2360  [0x185d490e0]
    +   2094 main (in Electron Helper) (electron_main_mac.cc:84) + 2544  [0x104d289f0]
    +     2094 ElectronMain (in Electron Framework) (electron_library_main.mm:26) + 180  [0x10e1a57fc]
    +       2094 content::ContentMain(content::ContentMainParams) (in Electron Framework) (content_main.cc:347) + 299864  [0x10e4ab024]
    +         2094 content::RunContentProcess(content::ContentMainParams, content::ContentMainRunner*) (in Electron Framework) (content_main.cc:334) + 299412  [0x10e4aae60]
    +           2094 content::ContentMainRunnerImpl::Run() (in Electron Framework) (content_main_runner_impl.cc:0) + 305156  [0x10e4ac4d0]
    +             2094 content::RunOtherNamedProcessTypeMain(std::__Cr::basic_string<char, std::__Cr::char_traits<char>, std::__Cr::allocator<char>> const&, content::MainFunctionParams, content::ContentMainDelegate*) (in Electron Framework) (content_main_runner_impl.cc:775) + 301824  [0x10e4ab7cc]
    +               2094 content::UtilityMain(content::MainFunctionParams) (in Electron Framework) (utility_main.cc:444) + 18717632  [0x110ea14b0]
    +                 2094 base::RunLoop::Run(base::Location const&) (in Electron Framework) (run_loop.cc:136) + 24943996  [0x11149166c]
    +                   2094 base::sequence_manager::internal::ThreadControllerWithMessagePumpImpl::Run(bool, base::TimeDelta) (in Electron Framework) (thread_controller_with_message_pump_impl.cc:631) + 25173124  [0x1114c9574]
    +                     2094 base::MessagePumpDefault::Run(base::MessagePump::Delegate*) (in Electron Framework) (message_pump_default.cc:41) + 24788856  [0x11146b868]
    +                       2094 non-virtual thunk to base::sequence_manager::internal::ThreadControllerWithMessagePumpImpl::DoWork() (in Electron Framework) (thread_controller_with_message_pump_impl.cc:0) + 25170312  [0x1114c8a78]
    +                         2094 base::TaskAnnotator::RunTaskImpl(base::PendingTask&) (in Electron Framework) (task_annotator.cc:201) + 25052240  [0x1114abd40]
    +                           2094 electron::NodeBindings::UvRunOnce() (in Electron Framework) (node_bindings.cc:891) + 17652  [0x10e32cac0]
    +                             2094 uv_run (in Electron Framework) (core.c:0) + 372  [0x10e194a60]
    +                               2094 uv__io_poll (in Electron Framework) (kqueue.c:0) + 1552  [0x10e1a4f88]
    +                                 2094 uv__async_io (in Electron Framework) (async.c:165) + 1124,1148,...  [0x10e19456c,0x10e194584,...]

[bpasero]

@tmm1 👏 great findings. Yes, @deepak1556 and me where tracing this issue as well some weeks ago using Instruments and found the call site, but were clueless as to how this could happen. We also figured out that updating to latest parcel watcher resolves this issue and that is actually the reason I went ahead and started an experiment to try out this new version. Unfortunately it has a serious bug and a engineering change that currently block us from adopting this version:

• Deadlock between Watcher and Debounce threads parcel-bundler/watcher#187
• Allow to consume with C++ sources to build as part of npm install parcel-bundler/watcher#191

The former, I was able to address in parcel-bundler/watcher#189 but needs a newer release.

The endless CPU spike only seems to happen when a massive amount of paths is watched at the same time, potentially overlapping, as it is the case before 88b706b landed where I enforce the TypeScript extension to re-use the workspace watcher instead of spawning their own.

I am still trying to get newer parcel watcher builds, but we are currently blocked and I hope things move on again soon so that we can update.

Thanks for your contributions to the watcher, if you see more things, please make sure to let us know 🙏

[tmm1]

Wow you guys are way ahead of me. Thanks for all the links, as I had missed this side of the discussion!

I suspected the npm distribution changes might be a problem. I will take a look there.