Analyzer response to LSP requests extremely slow w/ high latency reported

[josephemorgan]

I'm intermittently having extremely slow dart analyzer performance with VS code around 10-15 times an hour.

A typical instance starts with me typing to fix an error or triggering autocomplete. When I do so, I get Loading... in the autocomplete pop-up, sometimes the VS Code status bar shows "Analyzing" with a spinner. While the analyzer is loading, error indicators in the editor window don't update (they'll report errors at locations that don't have errors) and autocomplete won't show anything. Sometimes, but not always, my editor will freeze completely until the analyzer unfreezes. The hangs usually last anywhere from 30 seconds to 3 minutes.

I suspect the issue might have something to do with how large the project is, or maybe there's something strange about our project configuration.

The analysis server diagnostics typically looks like this after freezing:

I understand that "latency" means the server is busy and can't start handling a request, is there any way to determine what it's busy doing?

Please let me know what other information I can provide or what debugging steps I can take.

Dart Info:

If providing this information as part of reporting a bug, please review the information
below to ensure it only contains things you're comfortable posting publicly.

#### General info

- Dart 3.4.4 (stable) (Wed Jun 12 15:54:31 2024 +0000) on "windows_x64"
- on windows / "Windows 10 Enterprise" 10.0 (Build 22631)
- locale is en-US

#### Project info

- sdk constraint: '>=3.3.4 <4.0.0'
- dependencies: accordion, app_links, auto_size_text, badges, barcode_widget, cached_network_image, camera, carousel_slider, chewie, collection, community_charts_flutter, confetti, configurable_expansion_tile_null_safety, connectivity_plus, data_table_2, datetime_picker_formfield_new, device_info_plus, easy_debounce, email_validator, exif, file_picker, firebase_core, firebase_core_platform_interface, firebase_messaging, flutter, flutter_barcode_scanner, flutter_cache_manager, flutter_date_pickers, flutter_expandable_table, flutter_file_dialog, flutter_keyboard_visibility, flutter_local_notifications, flutter_quill, flutter_slidable, flutter_speed_dial, flutter_spinkit, flutter_svg, flutter_typeahead, flutter_uploader, flutter_video_info, geocoding, geolocator, google_maps_flutter, googleapis, hive, horizontal_data_table, http, image, image_gallery_saver, image_network, image_picker, infinite_scroll_pagination, intl, jiffy, keyboard_actions, latlong2, liquid_pull_to_refresh, logger, material_design_icons_flutter, material_symbols_icons, mime, modal_progress_hud_nsn, multi_dropdown, neat_periodic_task, open_filex, package_info_plus, path, path_drawing, path_provider, pdf, percent_indicator, permission_handler, phone_form_field, photo_view, pointer_interceptor, printing, provider, screenshot, scroll_to_index, scrollable_positioned_list, share_plus, shared_preferences, sliding_up_panel, super_tooltip, table_calendar, timeago, toggle_switch, transparent_image, tuple, universal_html, universal_io, url_launcher, uuid, vector_math, version, video_player, video_thumbnail, visibility_detector, wakelock_plus
- dev_dependencies: flutter_launcher_icons, flutter_lints, flutter_test, integration_test, pubspec_dependency_sorter
- elided dependencies: 1

#### Process info

|  Memory | CPU | Elapsed time | Command line |
| ------: | --: | -----------: | ------------ |
|   12 MB |  -- |              | dart.exe     |
| 2828 MB |  -- |              | dart.exe     |
|   34 MB |  -- |              | dart.exe     |
|   15 MB |  -- |              | dart.exe     |
|   68 MB |  -- |              | dart.exe     |
|  167 MB |  -- |              | dart.exe     |
|   95 MB |  -- |              | dart.exe     |

Flutter Doctor:

Doctor summary (to see all details, run flutter doctor -v):
[√] Flutter (Channel stable, 3.22.3, on Microsoft Windows [Version 10.0.22631.3880], locale en-US)
[√] Windows Version (Installed version of Windows is version 10 or higher)
[√] Android toolchain - develop for Android devices (Android SDK version 33.0.2)
[√] Chrome - develop for the web
[√] Visual Studio - develop Windows apps (Visual Studio Professional 2022 17.7.7)
[√] Android Studio (version 2024.1)
[√] VS Code (version unknown)
    X Unable to determine VS Code version.
[√] VS Code, 64-bit edition (version 1.91.1)
[√] VS Code (version 1.92.0-insider)
[√] Connected device (4 available)
[√] Network resources

[dart-github-bot]

Summary: The Dart analyzer in VS Code is experiencing intermittent slowness, causing delays in autocomplete, error reporting, and editor responsiveness. The issue occurs multiple times per hour and lasts for 30 seconds to 3 minutes. The user suspects the project size or configuration might be contributing to the problem.

[bwilkerson]

@DanTup In case you can help in terms of getting enough information to be able to determine the reason for the long analysis times.

[DanTup]

I understand that "latency" means the server is busy and can't start handling a request, is there any way to determine what it's busy doing?

Latency here is the time difference between use constructing a request to the analysis server (done in the VS Code extension) and the server starting to process it. It generally means the analysis server was busy (it's single threaded) although there is the possibility that the delay could be in the VS Code side (especially if it itself is hanging!) or affected by other VS Code extensions (since all extensions run single-threaded in a single Node process).

Temporarily enabling the analysis server instrumentation log might give some insight into what the server is doing during this period. The file can get very large and will contain contents of your files, so sharing these logs may be difficult, but if you can get a copy of one after this happens, we may be able to provide some idea of what to look for in it (in particular I wonder if something like a context rebuild is happening - something that can occur if a pubspec.yaml or package_config.json changes).

Sometimes, but not always, my editor will freeze completely until the analyzer unfreezes.

Is it only the editor that freezes when this happens, or the system in general? Have you ever been able to view Task Manager (or run code --status in a terminal) while this is happening? VS Code runs all extensions in another process to protect itself from any bad extensions ever hanging the editor (even if they're very slow or running infinite loops) so if VS Code is hanging, there might be something more.

The output of code --status might be useful when you have this project open (even when it's not hanging - although while hanging would be more useful). I notice you have 7 Dart processes in your list before - if you have multiple VS Code windows open, please do the same when running code --status so the stats of both are included.

[josephemorgan]

Latency here is the time difference between use constructing a request to the analysis server (done in the VS Code extension) and the server starting to process it. It generally means the analysis server was busy (it's single threaded) although there is the possibility that the delay could be in the VS Code side (especially if it itself is hanging!) or affected by other VS Code extensions (since all extensions run single-threaded in a single Node process).

Thank you for the info. I also use VSCode for dotnet and Angular development and haven't encountered the issue there, but it's possible that it's a dart specific plugin. Think all I've got installed is the official Dart plugin and the Dart Data Class Generator.

Temporarily enabling the analysis server instrumentation log might give some insight into what the server is doing during this period.

I'll do that today and update this issue with some logs.

Is it only the editor that freezes when this happens, or the system in general? Have you ever been able to view Task Manager (or run code --status in a terminal) while this is happening? VS Code runs all extensions in another process to protect itself from any bad extensions ever hanging the editor (even if they're very slow or running infinite loops) so if VS Code is hanging, there might be something more.

The editor freezing is relatively uncommon, seems like it only happens when I save a file, status bar say something along the lines of "saving and applying code actions". I've never had the system itself freeze, and whenever I've looked at the task manager during one of these episodes, I haven't noticed anything strange. Some high-ish CPU usage, but not like it's pegged at 100% or anything.

The output of code --status might be useful when you have this project open (even when it's not hanging - although while hanging would be more useful). I notice you have 7 Dart processes in your list before - if you have multiple VS Code windows open, please do the same when running code --status so the stats of both are included.

Here's that output, not hanging currently but I'll grab it again as soon as it is:

Version:          Code 1.91.1 (f1e16e1e6214d7c44d078b1f0607b2388f29d729, 2024-07-09T22:06:49.809Z)
OS Version:       Windows_NT x64 10.0.22631
CPUs:             Intel(R) Core(TM) i7-10750H CPU @ 2.60GHz (12 x 2592)
Memory (System):  31.76GB (12.17GB free)
VM:               0%
Screen Reader:    yes
Process Argv:     --crash-reporter-id 0ca3f427-aab5-4c5b-b043-89b5f1cceb7e
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

CPU %   Mem MB     PID  Process
    0      151   20420  code main
    0      110    1428  shared-process
    0      431   12092  extensionHost [1]
    0        4    3212       C:\WINDOWS\system32\cmd.exe /d /s /c ""c:\Users\morganj\.vscode\extensions\vscjava.vscode-gradle-3.15.0\lib\gradle-server.bat" 64097"
    0        6     632         C:\WINDOWS\system32\conhost.exe 0x4
    0       16   21588         "java.exe"  "-Dfile.encoding=UTF-8"    -classpath "c:\Users\morganj\.vscode\extensions\vscjava.vscode-gradle-3.15.0\lib\gradle-server.jar" com.github.badsyntax.gradle.GradleServer 64097
    0     2139   10052       C:\Users\morganj\fvm\versions\3.22.3\bin\cache\dart-sdk\bin\dart.exe language-server --protocol=lsp --client-id=VS-Code --client-version=3.92.0
    0        6   21648         C:\WINDOWS\system32\conhost.exe 0x4
    0       15   11664       java -Dfile.encoding=utf8 -jar c:\Users\morganj\.vscode\extensions\vscjava.vscode-gradle-3.15.0\lib\gradle-language-server.jar
    0        6    1492         C:\WINDOWS\system32\conhost.exe 0x4
    0       15   12484       C:\Users\morganj\fvm\versions\3.22.3\bin\cache\dart-sdk\bin\dart.exe devtools --machine --allow-embedding --dtd-uri ws://127.0.0.1:64047/9YLvBwARxGQndzcX
    0        6   20944         C:\WINDOWS\system32\conhost.exe 0x4
    0       79   12572       "C:\Program Files\Microsoft VS Code\Code.exe" "c:\Program Files\Microsoft VS Code\resources\app\extensions\json-language-features\server\dist\node\jsonServerMain" --node-ipc --clientProcessId=12092
    0        4   19860       electron-nodejs (config.js )
    0        6   14108         C:\WINDOWS\system32\conhost.exe 0x4
    0      112   26084         electron-nodejs (config.js )
    0       66   10180           "c:\Users\morganj\.vscode\extensions\ms-dotnettools.csdevkit-1.9.8-win32-x64\components\vs-green-server\platforms\win32-x64\node_modules\@microsoft\servicehub-controller-net60.win32-x64/Microsoft.ServiceHub.Controller" 6b82d25fbc481d1d2ed7514c707d2d8834b1716bfa49e2165de7076c310ab38b /ControllerCooldownTimeout:30000 "/TelemetrySession:{\"TelemetryLevel\":\"all\",\"IsOptedIn\":false,\"HostName\":\"Default\",\"AppInsightsInstrumentationKey\":null,\"AsimovInstrumentationKey\":null,\"CollectorApiKey\":\"0c6ae279ed8443289764825290e4f9e2-1a736e7c-1324-4338-be46-fc2a58ae4d14-7255\",\"AppId\":1010,\"UserId\":\"9db3f0d7-e564-4a0d-a0d1-141ce41d6a3f\",\"Id\":\"c766d778-5823-44a2-aefb-ad2d612eed681721697226550\",\"ProcessStartTime\":133661708407598265,\"SkuName\":null,\"VSExeVersion\":null,\"BucketFiltersToEnableWatsonForFaults\":[{\"AdditionalProperties\":[{\"Key\":\"DumpType\",\"Value\":\"Heap\"}],\"Id\":\"0bf51120-427a-4d11-9fa3-8825e8a6b42b\",\"WatsonEventType\":\"VisualStudioNonFatalErrors2\",\"BucketParameterFilters\":[\"(?i)servicehub.identityhost.exe\",null,\"(?i)servicehub.host.serviceactivationfailure\",\"(?i)microsoft.servicehub.hostlib.proxyexception\",null,null,null,null,null,null]}],\"BucketFiltersToAddDumpsToFaults\":[{\"AdditionalProperties\":[{\"Key\":\"DumpType\",\"Value\":\"Heap\"}],\"Id\":\"0bf51120-427a-4d11-9fa3-8825e8a6b42b\",\"WatsonEventType\":\"VisualStudioNonFatalErrors2\",\"BucketParameterFilters\":[\"(?i)servicehub.identityhost.exe\",null,\"(?i)servicehub.host.serviceactivationfailure\",\"(?i)microsoft.servicehub.hostlib.proxyexception\",null,null,null,null,null,null]}]}"
    0       76    1932             "c:\Users\morganj\.vscode\extensions\ms-dotnettools.csdevkit-1.9.8-win32-x64\components\vs-green-server\platforms\win32-x64\node_modules\@microsoft\visualstudio-code-servicehost.win32-x64/Microsoft.VisualStudio.Code.ServiceHost.exe" dotnet$C94B8CFE-E3FD-4BAF-A941-2866DBB566FE net.pipe://1018076C939D52D2717834D7A0F41DF38AD89 "/TelemetrySession:{\"TelemetryLevel\":\"all\",\"IsOptedIn\":false,\"HostName\":\"Default\",\"AppInsightsInstrumentationKey\":null,\"AsimovInstrumentationKey\":null,\"CollectorApiKey\":\"0c6ae279ed8443289764825290e4f9e2-1a736e7c-1324-4338-be46-fc2a58ae4d14-7255\",\"AppId\":1010,\"UserId\":\"9db3f0d7-e564-4a0d-a0d1-141ce41d6a3f\",\"Id\":\"c766d778-5823-44a2-aefb-ad2d612eed681721697226550\",\"ProcessStartTime\":133661708407598265,\"SkuName\":null,\"VSExeVersion\":null,\"BucketFiltersToEnableWatsonForFaults\":[{\"AdditionalProperties\":[{\"Key\":\"DumpType\",\"Value\":\"Heap\"}],\"Id\":\"0bf51120-427a-4d11-9fa3-8825e8a6b42b\",\"WatsonEventType\":\"VisualStudioNonFatalErrors2\",\"BucketParameterFilters\":[\"(?i)servicehub.identityhost.exe\",null,\"(?i)servicehub.host.serviceactivationfailure\",\"(?i)microsoft.servicehub.hostlib.proxyexception\",null,null,null,null,null,null]}],\"BucketFiltersToAddDumpsToFaults\":[{\"AdditionalProperties\":[{\"Key\":\"DumpType\",\"Value\":\"Heap\"}],\"Id\":\"0bf51120-427a-4d11-9fa3-8825e8a6b42b\",\"WatsonEventType\":\"VisualStudioNonFatalErrors2\",\"BucketParameterFilters\":[\"(?i)servicehub.identityhost.exe\",null,\"(?i)servicehub.host.serviceactivationfailure\",\"(?i)microsoft.servicehub.hostlib.proxyexception\",null,null,null,null,null,null]}]}"
    0        6    5212               C:\WINDOWS\system32\conhost.exe 0x4
    0      147   19852             "c:\Users\morganj\.vscode\extensions\ms-dotnettools.csdevkit-1.9.8-win32-x64\components\vs-green-server\platforms\win32-x64\node_modules\@microsoft\visualstudio-code-servicehost.win32-x64\Microsoft.VisualStudio.Code.ServiceHost.exe" dotnet.projectSystem$C94B8CFE-E3FD-4BAF-A941-2866DBB566FE net.pipe://1018076C939D52D2717834D7A0F41DF38AD89 "/TelemetrySession:{\"TelemetryLevel\":\"all\",\"IsOptedIn\":false,\"HostName\":\"Default\",\"AppInsightsInstrumentationKey\":null,\"AsimovInstrumentationKey\":null,\"CollectorApiKey\":\"0c6ae279ed8443289764825290e4f9e2-1a736e7c-1324-4338-be46-fc2a58ae4d14-7255\",\"AppId\":1010,\"UserId\":\"9db3f0d7-e564-4a0d-a0d1-141ce41d6a3f\",\"Id\":\"c766d778-5823-44a2-aefb-ad2d612eed681721697226550\",\"ProcessStartTime\":133661708407598265,\"SkuName\":null,\"VSExeVersion\":null,\"BucketFiltersToEnableWatsonForFaults\":[{\"AdditionalProperties\":[{\"Key\":\"DumpType\",\"Value\":\"Heap\"}],\"Id\":\"0bf51120-427a-4d11-9fa3-8825e8a6b42b\",\"WatsonEventType\":\"VisualStudioNonFatalErrors2\",\"BucketParameterFilters\":[\"(?i)servicehub.identityhost.exe\",null,\"(?i)servicehub.host.serviceactivationfailure\",\"(?i)microsoft.servicehub.hostlib.proxyexception\",null,null,null,null,null,null]}],\"BucketFiltersToAddDumpsToFaults\":[{\"AdditionalProperties\":[{\"Key\":\"DumpType\",\"Value\":\"Heap\"}],\"Id\":\"0bf51120-427a-4d11-9fa3-8825e8a6b42b\",\"WatsonEventType\":\"VisualStudioNonFatalErrors2\",\"BucketParameterFilters\":[\"(?i)servicehub.identityhost.exe\",null,\"(?i)servicehub.host.serviceactivationfailure\",\"(?i)microsoft.servicehub.hostlib.proxyexception\",null,null,null,null,null,null]}]}"
    0       45     968               "C:\Program Files\dotnet\dotnet.exe" "c:\Users\morganj\.vscode\extensions\ms-dotnettools.csdevkit-1.9.8-win32-x64\components\CPS\platforms\win32-x64\node_modules\@microsoft\visualstudio-projectsystem-buildhost.win32-x64/Microsoft.VisualStudio.ProjectSystem.Server.BuildHost.dll"
    0        6    6180                 C:\WINDOWS\system32\conhost.exe 0x4
    0        6   18720               C:\WINDOWS\system32\conhost.exe 0x4
    0       13   20148       C:\Users\morganj\fvm\versions\3.22.3\bin\cache\dart-sdk\bin\dart.exe tooling-daemon --machine
    0        6    5532         C:\WINDOWS\system32\conhost.exe 0x4
    0       77   23848       electron-nodejs (serverMain.js )
    0        4   24996       C:\WINDOWS\system32\cmd.exe /c C:\Users\morganj\fvm\versions\3.22.3\bin\flutter.bat debug_adapter
    0        6   26524         C:\WINDOWS\system32\conhost.exe 0x4
    0       37   26600         electron-nodejs (config.js )
    0        4   10688           C:\WINDOWS\system32\cmd.exe /c C:\Users\morganj\fvm\versions\3.22.3\bin\flutter.bat run --machine --start-paused -d emulator-5554 --devtools-server-address http://127.0.0.1:9100/ --target C:\Users\morganj\source\CAFDExGO\mobile_app\lib\main.dart
    0       62    3816             electron-nodejs (config.js )
    0        8    2416               C:\Users\morganj\AppData\Local\Android\sdk\platform-tools\adb.exe -s emulator-5554 shell -x logcat -v time -T "'07-23 10:35:50.197'"
    0        6   14060                 C:\WINDOWS\system32\conhost.exe 0x4
    0       49   13840               electron-nodejs (config.js )
    0        6   10092                 C:\WINDOWS\system32\conhost.exe 0x4
    0        6   19840             C:\WINDOWS\system32\conhost.exe 0x4
    0      181   25184       c:\Users\morganj\.vscode\extensions\ms-dotnettools.csharp-2.34.12-win32-x64\.roslyn\Microsoft.CodeAnalysis.LanguageServer.exe --logLevel Information --razorSourceGenerator c:\Users\morganj\.vscode\extensions\ms-dotnettools.csharp-2.34.12-win32-x64\.razor\Microsoft.CodeAnalysis.Razor.Compiler.dll --razorDesignTimePath c:\Users\morganj\.vscode\extensions\ms-dotnettools.csharp-2.34.12-win32-x64\.razor\Targets\Microsoft.NET.Sdk.Razor.DesignTime.targets --starredCompletionComponentPath c:\Users\morganj\.vscode\extensions\ms-dotnettools.vscodeintellicode-csharp-2.1.11-win32-x64\components\starred-suggestions\platforms\win32-x64\node_modules\@vsintellicode\starred-suggestions-csharp.win32-x64 --devKitDependencyPath c:\Users\morganj\.vscode\extensions\ms-dotnettools.csharp-2.34.12-win32-x64\.roslynDevKit\Microsoft.VisualStudio.LanguageServices.DevKit.dll --sessionId c766d778-5823-44a2-aefb-ad2d612eed681721697226550 --extension c:\Users\morganj\.vscode\extensions\ms-dotnettools.csharp-2.34.12-win32-x64\.xamlTools\Microsoft.VisualStudio.DesignTools.CodeAnalysis.dll --extension c:\Users\morganj\.vscode\extensions\ms-dotnettools.csharp-2.34.12-win32-x64\.xamlTools\Microsoft.VisualStudio.DesignTools.CodeAnalysis.Diagnostics.dll --telemetryLevel all --extensionLogDirectory c:\Users\morganj\AppData\Roaming\Code\logs\20240722T181345\window1\exthost\ms-dotnettools.csharp
    0        4   25404       C:\WINDOWS\system32\cmd.exe /d /s /c ""C:\Users\morganj\fvm\versions\3.22.3\bin\flutter.bat" "daemon""
    0        6    2820         C:\WINDOWS\system32\conhost.exe 0x4
    0       28   12672         electron-nodejs (config.js )
    0        6   22380           C:\Users\morganj\AppData\Local\Android\sdk\emulator\emulator.exe -avd Pixel_7_API_33 -no-snapshot-load
    0        6   11324             C:\WINDOWS\system32\conhost.exe 0x4
    0     2065   24372             C:\Users\morganj\AppData\Local\Android\sdk\emulator\qemu\windows-x86_64\qemu-system-x86_64.exe -avd Pixel_7_API_33 -no-snapshot-load
    0        6    5768               C:\Users\morganj\AppData\Local\Android\sdk\emulator\crashpad_handler.exe --no-rate-limit --database=C:\Users\morganj\AppData\Local\Temp\\AndroidEmulator\emu-crash.db --url=https://clients2.google.com/cr/report --annotation=prod=AndroidEmulator --annotation=ver=standalone-0 --initial-client-data=0x3e0,0x3e4,0x3e8,0x3bc,0xa8,0x7ff70cace3a8,0x7ff70cace3b8,0x7ff70cace378
    0       79   25880       electron-nodejs (tailwindServer.js )
    0       89   26116       electron-nodejs (languageserver.js )
    0       77   26312       electron-nodejs (eslintServer.js )
    0       74   12204  fileWatcher [1]
    0      177   19704     gpu-process
    0       42   20892     utility-network-service
    0      662   25144  window [1] (priorities_new.dart - mobile_app (Workspace) - Visual Studio Code)
    0       25   25964     crashpad-handler
    0       80   25980  ptyHost
    0       79     392       C:\WINDOWS\System32\WindowsPowerShell\v1.0\powershell.exe -noexit -command "try { . \"c:\Program Files\Microsoft VS Code\resources\app\out\vs\workbench\contrib\terminal\browser\media\shellIntegration.ps1\" } catch {}"
    0        5   30276         C:\WINDOWS\system32\cmd.exe /c ""C:\Program Files\Microsoft VS Code\bin\code.cmd" --status"
    0      101   24764           electron-nodejs (cli.js )
    0      129   26284             "C:\Program Files\Microsoft VS Code\Code.exe" --status
    0       90   14752               crashpad-handler
    0       92   19108               utility-network-service
    0      104   21316               gpu-process
    0        7   20596       conpty-agent
    0       29   24984       "C:\Program Files\dotnet\dotnet.exe" watch run C:\Users\morganj\source\CAFDExGO\APIServer-Test/CAFDExGOServer.csproj --property GenerateFullPaths=true
    0       34   26108         "C:\Program Files\dotnet\dotnet.exe" "C:\Program Files\dotnet\sdk\6.0.408\DotnetTools\dotnet-watch\6.0.408-servicing.23177.15\tools\net6.0\any\dotnet-watch.dll" run C:\Users\morganj\source\CAFDExGO\APIServer-Test/CAFDExGOServer.csproj --property GenerateFullPaths=true
    0       48    2812           "C:\Program Files\dotnet\dotnet.exe" run --no-restore C:\Users\morganj\source\CAFDExGO\APIServer-Test/CAFDExGOServer.csproj --property GenerateFullPaths=true
    0      179   25208             "C:\Users\morganj\source\CAFDExGO\APIServer-Test\bin\Debug\net6.0\CAFDExGOServer.exe"  C:\Users\morganj\source\CAFDExGO\APIServer-Test/CAFDExGOServer.csproj
    0        7   25512       conpty-agent

Workspace Stats:
|  Window (priorities_new.dart - mobile_app (Workspace) - Visual Studio Code)
|    Folder (Database): 2304 files
|      File types: svn-base(1332) sql(690) xlsx(3) db(1) db-journal(1) json(1)
|                  docx(1) js(1)
|      Conf files: tasks.json(1)
|    Folder (APIServer-Test): 5211 files
|      File types: svn-base(3446) cs(935) dll(153) pak(60) json(47) cache(10)
|                  exe(8) bin(8) vsidx(7) config(6)
|      Conf files: package.json(4) project.json(2) launch.json(1)
|                  settings.json(1) tasks.json(1) csproj(1) sln(1)
|      Launch Configs: coreclr(2)
|    Folder (mobile_app): more than 20293 files
|      File types: svn-base(2816) png(1773) dart(1737) h(1351) svg(1206)
|                  class(926) jar(919) json(417) xml(377) txt(255)
|      Conf files: cmake(25) sln(14) launch.json(1) settings.json(1)
|      Launch Configs: dart(11)

[josephemorgan]

I also should have mentioned that my teammates have also complained about hangs/slowness in the same project, which is what makes me suspicious that there might be something about the project itself that is causing some issues.

In my initial efforts to debug, I went through analysis_options.yaml and denylisted everything in the workspace directory except for lib, but I still had the issue.

[josephemorgan]

Some additional info:

I dug into the Analysis Server Diagnostics and saw that there are a handful of exceptions. The exceptions throw out an enormous wall of text that starts with: Exception Invalid argument(s): Missing library: package:com.infintech.cafdexgo/assessment/widgets/assessment_date_card.dart Libraries: [dart:async, dart:collection, dart:convert, dart:core, dart:_internal, dart:math, dart:typed_data, dart:isolate, dart:developer, dart:ffi, dart:_http, dart:io, ...

I verified that the indicated library exists at lib/assessment/widgets/assessment_date_card.dart

Stack trace from the diagnostics page looks like this:

#0      LinkedElementFactory.createLibraryElementForReading (package:analyzer/src/summary2/linked_element_factory.dart:153:7)
#1      LinkedElementFactory.elementOfReference (package:analyzer/src/summary2/linked_element_factory.dart:212:14)
#2      LinkedElementFactory.libraryOfUri (package:analyzer/src/summary2/linked_element_factory.dart:241:12)
#3      LinkedElementFactory.libraryOfUri2 (package:analyzer/src/summary2/linked_element_factory.dart:245:19)
#4      ResolutionReader.libraryOfUri (package:analyzer/src/summary2/bundle_reader.dart:1940:28)
#5      LibraryElementLinkedData._readLibraryOrAugmentation (package:analyzer/src/summary2/bundle_reader.dart:587:30)
#6      LibraryElementLinkedData._read (package:analyzer/src/summary2/bundle_reader.dart:536:5)
#7      ElementLinkedData.read (package:analyzer/src/summary2/bundle_reader.dart:256:5)
#8      LibraryElementLinkedData.read (package:analyzer/src/summary2/bundle_reader.dart:520:13)
#9      LibraryElementImpl.exportNamespace (package:analyzer/src/dart/element/element.dart:4176:17)
#10     LibraryElementExtensions.exportedExtensions (package:analysis_server/src/utilities/extensions/element.dart:61:12)
#11     _ImportLibraryContainingExtension.compute (package:analysis_server/src/services/correction/dart/import_library.dart:461:42)
#12     FixProcessor._addFromProducers.compute (package:analysis_server/src/services/correction/fix_processor.dart:123:24)
#13     FixProcessor._addFromProducers (package:analysis_server/src/services/correction/fix_processor.dart:161:17)
<asynchronous suspension>
#14     FixProcessor.compute (package:analysis_server/src/services/correction/fix_processor.dart:75:5)
<asynchronous suspension>
#15     computeFixes (package:analysis_server/src/services/correction/fix_internal.dart:1587:8)
<asynchronous suspension>
#16     DartCodeActionsProducer.getFixActions (package:analysis_server/src/lsp/handlers/code_actions/dart.dart:178:23)
<asynchronous suspension>
#17     OperationPerformanceImpl.runAsync (package:analyzer/src/util/performance/operation_performance.dart:172:14)
<asynchronous suspension>
#18     CodeActionHandler.handle (package:analysis_server/src/lsp/handlers/handler_code_actions.dart:227:16)
<asynchronous suspension>
#19     ServerStateMessageHandler.handleMessage (package:analysis_server/src/lsp/handlers/handlers.dart:396:11)
<asynchronous suspension>
#20     LspAnalysisServer._handleRequestMessage (package:analysis_server/src/lsp/lsp_analysis_server.dart:1010:20)
<asynchronous suspension>
#21     LspAnalysisServer.handleMessage.<anonymous closure>.<anonymous closure> (package:analysis_server/src/lsp/lsp_analysis_server.dart:461:15)
<asynchronous suspension>
#22     OperationPerformanceImpl.runAsync (package:analyzer/src/util/performance/operation_performance.dart:172:14)
<asynchronous suspension>
#23     LspAnalysisServer.handleMessage.<anonymous closure> (package:analysis_server/src/lsp/lsp_analysis_server.dart:444:11)
<asynchronous suspension>

There were 10 similar errors listed, it seems possible that they're connected to the hangs.

[bwilkerson]

@scheglov

[scheglov]

This is the same exception again, I still suspect that this is because we try to do more than one operation concurrently in DAS: analysis and handling requests. The solution is probably using a single scheduler.

[josephemorgan]

I've captured some analysis-server.log output during a time period that I was experiencing a lot of hangs. The worst hangs were happening on save, with the status bar showing "applying quick-fixes," but I did have a period after a save hang was complete where the autocomplete suggestion box was just showing "loading" and inline diagnostics weren't updating.

excerpt.txt

The excerpt that I extracted only covers ~3 minutes but it's about 5600 lines long.

The project that I'm working in does have 442 warnings and >2k infos, could that be why the analyzer is getting stuck?