Chat causes extension host OOM when workspace contains build artifacts

[sthaber]

As of version 0.23.2, GitHub Copilot chat in VSCode has become unusable in our organization. When changes are made to the build directory in our source tree, chat seems to pick them up and balloon in memory. Deleting a few thousand files from build is enough for the chat extension to run the extension host on the system out of memory and get OOMkilled (60+ GB of memory in use by chat). This happens whether or not the build directory is included in or excluded from the VSCode workspace. We use vanilla Ubuntu 22.04 as our dev environment and use the remote server to connect to laptops for editing. Chat extension version 0.22.0 does not have this issue and sits at a steady ~1GB regardless of build activity. It broke somewhere between 0.22.0 and 0.23.2. I did not bisect. We have pinned 0.22.0 as a workaround for now.

• Copilot Chat Extension Version: 0.23.2
• VS Code Version: 1.96.4
• OS Version: Ubuntu 22.04 (server host), various clients (Windows, Mac, Linux, repros on all)
• Logs: Attached below

Steps to Reproduce:

1. Set up a workspace that includes build artifacts in the source tree. In our environment this includes binary objects, JSON, autogenerated code, and a bunch of other stuff. Not sure exactly what triggers chat to explode.
2. Run build while watching htop or similar on the host server, sorted by memory usage.
3. Observe very high memory usage from the code extension host.
4. Roll Copilot Chat back to version 0.23.1 and rerun; no issue.

GitHub Copilot Chat.log
remoteexthost.log -- I redacted some details about our source tree but let me know if you need more info.

[sean-mcmanus]

I appear to repro the same issue, but using files.exclude to exclude the build folder appears to fix the issue for me and in my case it only repros when the C/C++ extension is also enabled. I sent repro details and memory logs to roblourens and the C/C++ Copilot team via email.

UPDATE: Using files.exclude didn't fix it. Looks like it was just a coincidence and it stopped reproing after I made that change, but then a few hours later it started reproing again, I'm not sure why.

[sthaber]

It's actually gotten quite a bit better since ~0.25.0. I no longer get the massive memory usage, but I'm having an adjacent problem with is that the extension host pegs at 100% CPU and VScode because inoperable for 1-3 minutes while it churns. I'm seeing this:

2025-03-07 09:46:22.255 [info] [Window] Extension host (Remote) is unresponsive.
2025-03-07 09:46:29.017 [info] [Window] Extension host (Remote) is responsive.
2025-03-07 09:47:10.616 [info] [Window] Extension host (Remote) is unresponsive.
2025-03-07 09:47:21.790 [info] [Window] Extension host (Remote) is responsive.
2025-03-07 09:47:25.555 [info] [Window] Extension host (Remote) is unresponsive.
2025-03-07 09:47:31.631 [info] [Window] Extension host (Remote) is responsive.

I've had build excluded this whole time:

    "files.exclude": {
        "**/*~": true,
        "**/*.orig": true,
        "**/*.rej": true,
        "**/.qpkg": true,
        "**/build": true,
    }

And it doesn't prevent the churn unfortunately. Something in the chat extension seems to be peeking in my build directory and ignoring the workspace config.

Also I haven't been using the C/C++ extension this whole time. The only C extension I use is ctagsx.

[sthaber]

My extensions. I try to run pretty light.

[sthaber]

Also I've lost the ability to roll back to somewhat recent versions, so this is heating up for us.

[sthaber]

None of this helps:

{
    // Hacking copilot, but it's not helping...
    "github.copilot.chat.edits.suggestRelatedFilesFromGitHistory": false,
    "github.copilot.chat.edits.suggestRelatedFilesForTests": false,
    "github.copilot.chat.codeGeneration.useInstructionFiles": false,
    "github.copilot.chat.agent.runTasks": false,
    "github.copilot.chat.fixTestFailure.enabled": false,
    "github.copilot.chat.followUps": "never",
    "github.copilot.chat.useProjectTemplates": false,
    "github.copilot.editor.enableCodeActions": false,
    "github.copilot.renameSuggestions.triggerAutomatically": false,
    "github.copilot.chat.copilotDebugCommand.enabled": false,
    "github.copilot.chat.reviewSelection.enabled": false,
    "github.copilot.chat.startDebugging.enabled": false,
    "github.copilot.chat.setupTests.enabled": false,
}

Disabling the extension still fixes it, but that's not my goal here.

[sthaber]

I found one other workaround: force copilot chat to run in the UI rather than the remote dev server:

    "remote.extensionKind": {
        "github.copilot": ["ui"],
        "github.copilot-chat": ["ui"],
    },

The CPU and memory problems are gone, but not all functionality works. Critically, the edits view just spews the edits and all their markup into the sidebar rather than editing the file. The inline editor and sidebar chat still work fine.

UPDATE: Never mind, it's just a different set of extensions that it hangs. It hangs all the local ones, including SSH sometimes.

[mjbvz]

Can you please try out the latest Copilot Chat nightly release (you'll also need the insiders build of VS Code)

I've made a number of fixes and improvements that should help with memory and cpu usage. Still a good idea to exclude build folders using files.exclude as Sean McManus (@sean-mcmanus) mentioned as we should observe that better too

If you're still running into the issue, please try to share an example project that causes the problem or steps to trigger it so I can investigate.