linter: small memory leak in IDE

[Boshen]

I still have this problem with the latest version, 1.19.0, the config file is just the import plugin and opening any file and closing it does free the memory. typing a character increases memory by ~10MB then deleting it also does not have the memory freed. I am using Cursor as my IDE and have also tested in VS Code. I made sure the imported/node_modules version of oxlint is 1.19.0 and the extension version is 1.19.0 as well.

Originally posted by @cypherpower in #10627

[Boshen]

@Sysix Can you help me setup a a main.rs that replicates this?

[camc314]

It looks like Runtime::modules_by_path which is a papaya::HashMap is never cleared, it's only ever inserted to never cleared? So i'm guessing closing the file should delete the entry from the hash map to release the memory?

[Sysix]

hm.. created another test setup in #14270.
Very similar to the old one #12100.

heaptrack stats:
        allocations:            51409231
        leaked allocations:     649
        temporary allocations:  1817111

Could not find a problem with the ServerLinter. Maybe the problem is Backend or Worker? Not really sure. 🤔

opening any file and closing it does free the memory.

The server only stores the file content and its diagnostic (after linting) when it is open. Closing it, will remove both.

typing a character increases memory by ~10MB then deleting it also does not have the memory freed.

Adding/Removing a character are didChange notifications and will be handled the same.
@cypherpower does it go up for every character you add/remove or only once?
What happens when you change the file content multiple times and then closing the file? Does all the memory get freed?

[cypherpower]

Here is a video, that I think should answer the questions @Sysix ? https://drive.proton.me/urls/9GG8RCHACR#hEQH4CwTSZqG. Let me know if I can help more.
I forgot to show the oxlint config file in that video but this is what it was { "plugins": [ "import" ] }

[Boshen]

@Sysix the videos seems to be leaking when opening and closing files?

Also, I found a small leak from the ignore walker crate if I change to the following code

    for i in 0..100 {
        let server = ServerLinter::new(
            &Uri::from_file_path(&fixture_path).unwrap(),
            &LintOptions::default(),
        );

        let _ = server
            .run_single(
                &uri,
                Some(format!("{}{}", content, " ".repeat(i))),
                ServerLinterRun::OnType,
            )
            .await;
    }

---

To find the leak, you can try https://docs.rs/dhat/latest/dhat with the viewer https://nnethercote.github.io/dh_view/dh_view.html

#[global_allocator]
static ALLOC: dhat::Alloc = dhat::Alloc;

#[tokio::main]
async fn main() {
    let _profiler = dhat::Profiler::new_heap();

    ...
}

Select "At t-end (bytes)" in "Sort metrics" - it reveals memory not dropped after main function exits.

[Sysix]

Want to share some information here:
Updated the PR to include the dhat profiler, but @Boshen did not find any visible leaks.
I could only find the memory leak with some external package like @react-three/fiber,
our import-plugin test did not grow the memory when changing the file:
https://github.com/oxc-project/oxc/tree/main/crates/oxc_language_server/fixtures/linter/cross_module

Added the dhat profiler to the real runtime and tested it with @react-three/fiber, here is the output:
dhat-heap-lsp.json