Extremely poor performance when working with large array literals

[jtanx]

Bug type: Language Service

Describe the bug

• OS and Version: Windows 10 20H2
• VS Code Version: 1.54.3
• C/C++ Extension Version: 1.2.2
• Other extensions you installed (and if the issue persists after disabling them):
• If using SSH remote, specify OS of remote machine: N/A

When working with large array literals, VSCode can lock up/freeze for extended periods of time.

Steps to reproduce

Lockup 1

1. Open this source file uninames.zip
2. Hover over lexicon or phrasebook
3. VSCode slows down, often freezing completely. Will sometimes report that the window is not responding:
   

Lockup 2

1. Open this source file: uninames2.zip
2. Collapse all the arrays:
   
3. Close the file (I'm doing this as part of a workspace)
4. Reopen the file, it will lock up here, choking on the collapsed arrays somehow

Expected behavior

Not locking up VSCode at a minimum, much better responsiveness would be ideal.

Code sample and logs

• Code sample: See above

• Configurations in c_cpp_properties.json: N/A

• Logs from running C/C++: Log Diagnostics from the VS Code command palette

-------- Diagnostics - 10/04/2021, 7:40:18 pm
Version: 1.2.2
Current Configuration:
{
    "name": "Win32",
    "includePath": [
        "C:/msys64/mingw32/include",
        "${workspaceFolder}/**"
    ],
    "defines": [
        "_DEBUG",
        "UNICODE",
        "_UNICODE"
    ],
    "windowsSdkVersion": "10.0.18362.0",
    "compilerPath": "C:/Program Files (x86)/Microsoft Visual Studio/2019/Community/VC/Tools/MSVC/14.26.28801/bin/Hostx64/x64/cl.exe",
    "cStandard": "c17",
    "intelliSenseMode": "windows-msvc-x64",
    "compilerArgs": [],
    "cppStandard": "c++17",
    "intelliSenseModeIsExplicit": true,
    "cStandardIsExplicit": true,
    "cppStandardIsExplicit": true,
    "compilerPathIsExplicit": true,
    "browse": {
        "path": [
            "C:/msys64/mingw32/include",
            "${workspaceFolder}/**"
        ],
        "limitSymbolsToIncludedHeaders": true
    }
}
Translation Unit Mappings:
[ C:\msys64\home\_\ffbuild\work\mingw32\fontforge\Unicode\uninames.c ]:
    C:\MSYS64\HOME\_\FFBUILD\WORK\MINGW32\FONTFORGE\UNICODE\UNINAMES.C
[ C:\Users\_\Documents\2019\FontForge\unicode\UnicodeData.txt ]:
    C:\USERS\_\DOCUMENTS\2019\FONTFORGE\UNICODE\UNICODEDATA.TXT
Translation Unit Configurations:
[ C:\msys64\home\_\ffbuild\work\mingw32\fontforge\Unicode\uninames.c ]:
    Process ID: 13176
    Memory Usage: 79 MB
    Compiler Path: C:/Program Files (x86)/Microsoft Visual Studio/2019/Community/VC/Tools/MSVC/14.26.28801/bin/Hostx64/x64/cl.exe
    Includes:
        C:\MSYS64\MINGW32\INCLUDE
        C:\PROGRAM FILES (X86)\MICROSOFT VISUAL STUDIO\2019\COMMUNITY\VC\TOOLS\MSVC\14.26.28801\INCLUDE
        C:\PROGRAM FILES (X86)\MICROSOFT VISUAL STUDIO\2019\COMMUNITY\VC\TOOLS\MSVC\14.26.28801\ATLMFC\INCLUDE
        C:\PROGRAM FILES (X86)\WINDOWS KITS\10\INCLUDE\10.0.18362.0\UM
        C:\PROGRAM FILES (X86)\WINDOWS KITS\10\INCLUDE\10.0.18362.0\UCRT
        C:\PROGRAM FILES (X86)\WINDOWS KITS\10\INCLUDE\10.0.18362.0\SHARED
        C:\PROGRAM FILES (X86)\WINDOWS KITS\10\INCLUDE\10.0.18362.0\WINRT
        C:\PROGRAM FILES (X86)\WINDOWS KITS\10\INCLUDE\10.0.18362.0\CPPWINRT
    Defines:
        _DEBUG
        UNICODE
        _UNICODE
    Standard Version: ms_c17
    IntelliSense Mode: windows-msvc-x64
[ C:\Users\_\Documents\2019\FontForge\unicode\UnicodeData.txt ]:
    Process ID: 12532
    Memory Usage: 28 MB
    Compiler Path: C:/Program Files (x86)/Microsoft Visual Studio/2019/Community/VC/Tools/MSVC/14.26.28801/bin/Hostx64/x64/cl.exe
    Includes:
        C:\MSYS64\MINGW32\INCLUDE
        C:\PROGRAM FILES (X86)\MICROSOFT VISUAL STUDIO\2019\COMMUNITY\VC\TOOLS\MSVC\14.26.28801\INCLUDE
        C:\PROGRAM FILES (X86)\MICROSOFT VISUAL STUDIO\2019\COMMUNITY\VC\TOOLS\MSVC\14.26.28801\ATLMFC\INCLUDE
        C:\PROGRAM FILES (X86)\WINDOWS KITS\10\INCLUDE\10.0.18362.0\UM
        C:\PROGRAM FILES (X86)\WINDOWS KITS\10\INCLUDE\10.0.18362.0\UCRT
        C:\PROGRAM FILES (X86)\WINDOWS KITS\10\INCLUDE\10.0.18362.0\SHARED
        C:\PROGRAM FILES (X86)\WINDOWS KITS\10\INCLUDE\10.0.18362.0\WINRT
        C:\PROGRAM FILES (X86)\WINDOWS KITS\10\INCLUDE\10.0.18362.0\CPPWINRT
    Defines:
        _DEBUG
        UNICODE
        _UNICODE
    Standard Version: ms_c17
    IntelliSense Mode: windows-msvc-x64
Total Memory Usage: 107 MB

------- Workspace parsing diagnostics -------
Number of folders and files enumerated: 27118
Number of files discovered (not excluded): 22699

• Logs from the language server logging

Checking for syntax errors: file:///c%3A/msys64/home/_/ffbuild/work/mingw32/fontforge/Unicode/uninames.c
Queueing IntelliSense update for files in translation unit of: C:\MSYS64\HOME\_\FFBUILD\WORK\MINGW32\FONTFORGE\UNICODE\UNINAMES.C
idle loop: reparsing the active document
Checking for syntax errors: file:///c%3A/msys64/home/_/ffbuild/work/mingw32/fontforge/Unicode/uninames.c
Queueing IntelliSense update for files in translation unit of: C:\MSYS64\HOME\_\FFBUILD\WORK\MINGW32\FONTFORGE\UNICODE\UNINAMES.C
Error squiggle count: 0
Update IntelliSense time (sec): 6.161
idle loop: reparsing the active document
Checking for syntax errors: file:///c%3A/Users/_/Documents/2019/FontForge/unicode/UnicodeData.txt
Queueing IntelliSense update for files in translation unit of: C:\USERS\_\DOCUMENTS\2019\FONTFORGE\UNICODE\UNICODEDATA.TXT
Error squiggle count: 31009
Update IntelliSense time (sec): 3.661
Request canceled: 78
idle loop: reparsing the active document
Checking for syntax errors: file:///c%3A/Users/_/Documents/2019/FontForge/unicode/UnicodeData.txt
Queueing IntelliSense update for files in translation unit of: C:\USERS\_\DOCUMENTS\2019\FONTFORGE\UNICODE\UNICODEDATA.TXT
Error squiggle count: 31009
Update IntelliSense time (sec): 3.209

Screenshots

Additional context

[sean-mcmanus]

We were returning too many characters on hover. The fix should be in 1.4.0-insiders (might not be available for a few weeks though).

[jtanx]

Nice, thanks!

Was that also the cause of the freeze when reopening the file with collapsed sections?

[sean-mcmanus]

Oops, yeah, the collapsing issue is different. I'm still investigating that...

[sean-mcmanus]

The freeze when opening VS Code with the regions collapsed appears to be a VS Code issue that repros when all extensions are disabled. You should file an issue at https://github.com/microsoft/vscode/issues . They may ask for additional performance data from https://github.com/microsoft/vscode/wiki/Performance-Issues , although the VS Code team should probably be able to get that info themselves by following the repro steps.

Don't mention the C/C++ extension and say you have all extensions disabled or they may blame our extension.

[jtanx]

Right, I see, thanks for your help!

[sean-mcmanus]

Fixed with https://github.com/microsoft/vscode-cpptools/releases/tag/1.4.0-insiders