Intellisense takes an extremely long time to finish scanning

[CendioOssman]

Environment

• OS and Version: Fedora 41
• VS Code Version: code-1.99.3-1744761644.el8.x86_64
• C/C++ Extension Version: 1.24.5

Bug Summary and Steps to Reproduce

Bug Summary:
Intellisense is almost unusable as it takes an extremely long time to update (at least minutes, possibly longer as I give up and just work without it).

Steps to reproduce:

1. Open source file in TigerVNC project

Expected behavior:
Intellisense is ready within seconds

Configuration and Logs

<details>
<summary>c_cpp_properties.json</summary>


{
    "configurations": [
        {
            "name": "Linux",
            "includePath": [
                "${workspaceFolder}/**"
            ],
            "defines": [],
            "cStandard": "c17",
            "cppStandard": "c++17"
        }
    ],
    "version": 4
}

</details>

I'm not seeing any C/C++ in the OUTPUT panel.

Other Extensions

No response

Additional context

This is not a big project. It only has 1000 files. Something must be very broken here, but I don't know how to give more clues.

The language server is sometimes using a lot of CPU, but often it is just hovering around 10%. So I don't know what it is doing instead of scanning my files.

[sean-mcmanus]

@CendioOssman Can you set C_Cpp.loggingLevel to "Debug" and look at the C/C++ output? Also, what does the C or C++ language status show on hover in the bottom right?

Also, 1.25.2 (pre-release) has a bunch of bug fixes, so you may want to try that too (we're planning to release that out of pre-release soon).

[CendioOssman]

@CendioOssman Can you set C_Cpp.loggingLevel to "Debug" and look at the C/C++ output?

It finally completed here now, so I guess not much fun to log anymore. But I can see if I can provoke it again and turn on the logging.

Also, what does the C or C++ language status show on hover in the bottom right?

Unfortunately, I didn't take a screenshot so I don't have the exact text.. But both the "Intellisense" and "Parsing open files" were actively spinning.

At the moment, only "Parsing open files" is stuck working. Although I only have a single file open.

[sean-mcmanus]

@CendioOssman If it's an IntelliSense update issue, then doing a right-click Restart IntelliSense for Active File could repro the issue again. "Parsing open files" also parses all the dependencies of a file. The "C/C++" logging should show "tag parsing" messages for the dependencies. If you see no logging and the cpptools process is not using any CPU, then it could be deadlocked (if hover is always stuck "Loading"). You could try setting C_Cpp.recursiveIncludes.reduce to "never" to cause IntelliSense to not be blocked on tag parsing if you keep hitting the issue.

[CendioOssman]

@CendioOssman If it's an IntelliSense update issue, then doing a right-click Restart IntelliSense for Active File could repro the issue again.

That does not seem to get Intellisense spinning for any long time. It now completes in 5-10 seconds.

"Parsing open files" is still working, though. And the database is wildly incomplete. If I use "Find all references", then only some hits actually show up. I also get this warning:

[Warning] Some references may be missing, because workspace parsing was incomplete when Find All References was started.

"Parsing open files" also parses all the dependencies of a file. The "C/C++" logging should show "tag parsing" messages for the dependencies. If you see no logging and the cpptools process is not using any CPU, then it could be deadlocked (if hover is always stuck "Loading"). You could try setting C_Cpp.recursiveIncludes.reduce to "never" to cause IntelliSense to not be blocked on tag parsing if you keep hitting the issue.

Yes, I'm seeing "tag parsing file", followed by "Database is safe to open" every now and the. But they are coming in very slowly. And there are no log lines besides those two.

I'm a bit unfamiliar with the distinction between the "Intellisense" and "Parsing open files" blocks. Are they both part of the Intellisense mechanism, or are they two different things?

[CendioOssman]

Actually, both processes just went idle:

But it still fails to find all references. But no longer warns.

[harry-cpp]

I'm seeing a lot of issues as well since updating the extension, it gets stuck on intelisense and pauses workspace parsing, last version that worked fine for me was 1.23.6 so downgraded to it and let it rescan the project.

I'll probably have time later this week to try and track down the commit that caused the issue for me.

Edit. Started using clangd extension to try it out, seems to work much better than this one so I won't try to track down the commit that caused the issue,

[github-actions]

This issue has been closed because it needs more information and has not had recent activity.