`kcl-language-server` crashes due to `MaxFilesWatch` error when more than `fs.inotify.max_user_watches` files are in `PWD`

[isbecker]

Bug Report

kcl-language-server crashes due to MaxFilesWatch error when more than fs.inotify.max_user_watches files are in PWD

1. Minimal reproduce step (Required)

I found this bug when using direnv with nix.

1. Install nix + direnv
2. Clone https://github.com/isbecker/kcl
3. Navigate to the directory and run direnv allow
4. You will now be in the devenv shell from flake.nix
   • this shell has kcl-language-server v0.11.1 installed directly from github releases
5. Use kcl-language-server, e.g. via kcl vscode extension
6. Set /proc/sys/fs/inotify/max_user_watches to 100000 or something that seems reasonable.
7. Observe .direnv/ directory has flake-outputs/ many files, more than 100000.
8. The vscode extension will inform you that the kcl-language-server crashed too many times and it is being stopped.

I also put together a devcontainer in the above mentioned repo, which I thought would help reproduce.
However, I noticed that it wasn't showing up in the devcontainer.

runner@codespaces-c24d64:/workspaces/kcl$ cat /proc/sys/fs/inotify/max_user_watches
524288

2. What did you expect to see? (Required)

I think that the new feature to watch the filesystem that was added in v0.11.0, should respect .gitignore. If that were the case, then .direnv/ could be easily added to .gitignore and this issue would be irrelevant (indeed, I usually do add it to my ignores because other tools also have similar issues to this, but generally respect .gitignore).

I expect that there should be a nicer error from kcl-language-server that tells me that the issue is fs.inotify.max_user_watches and it can inform me that I can increase the number.

3. What did you see instead (Required)

kcl-language-server crashes repeatedly, due to the new file watching (added in #1564 and first released in v0.11.0).

Observe these logs from the nvim-lsp logs below:

[START][2025-02-20 08:00:22] LSP logging initiated
[ERROR][2025-02-20 08:00:22] .../vim/lsp/rpc.lua:770	"rpc"	"/nix/store/mdvc9srx40fl1637cm61xgjlphicvfby-kcl-language-server-0.11.1/bin/kcl-language-server"	"stderr"	"thread 'main' panicked at tools/src/LSP/src/state.rs:579:22:\ncalled `Result::unwrap()` on an `Err` value: Error { kind: MaxFilesWatch, paths: [\"/path/to/my/project/.direnv/flake-inputs/yzv2p09a0pmxps631z44civzsffl89m5-source/pkgs/kde/frameworks/purpose\"] }\nnote: run with `RUST_BACKTRACE=1` environment variable to display a backtrace\n"
[ERROR][2025-02-20 08:00:34] .../vim/lsp/rpc.lua:770	"rpc"	"/nix/store/mdvc9srx40fl1637cm61xgjlphicvfby-kcl-language-server-0.11.1/bin/kcl-language-server"	"stderr"	"thread 'main' panicked at tools/src/LSP/src/state.rs:579:22:\ncalled `Result::unwrap()` on an `Err` value: Error { kind: MaxFilesWatch, paths: [\"/path/to/my/project/.direnv/flake-inputs/yzv2p09a0pmxps631z44civzsffl89m5-source/pkgs/kde/frameworks/purpose\"] }"
[ERROR][2025-02-20 08:00:34] .../vim/lsp/rpc.lua:770	"rpc"	"/nix/store/mdvc9srx40fl1637cm61xgjlphicvfby-kcl-language-server-0.11.1/bin/kcl-language-server"	"stderr"	"\nnote: run with `RUST_BACKTRACE=1` environment variable to display a backtrace\n"
[START][2025-02-20 08:00:40] LSP logging initiated
[ERROR][2025-02-20 08:00:40] .../vim/lsp/rpc.lua:770	"rpc"	"/nix/store/mdvc9srx40fl1637cm61xgjlphicvfby-kcl-language-server-0.11.1/bin/kcl-language-server"	"stderr"	"thread 'main' panicked at tools/src/LSP/src/state.rs:579:22:\ncalled `Result::unwrap()` on an `Err` value: Error { kind: MaxFilesWatch, paths: [\"/path/to/my/project/.direnv/flake-inputs/yzv2p09a0pmxps631z44civzsffl89m5-source/pkgs/kde/frameworks/purpose\"] }\nnote: run with `RUST_BACKTRACE=1` environment variable to display a backtrace\n"

Notably, the error is value: Error { kind: MaxFilesWatch. This behavior is due to the fact that I am using nix + direnv. As you can see from the kcl-language-server logs, the directories that are cuasing this are all .direnv

In that .direnv/flake-inputs directory, there are 316262 files. That is because it is my entire dev environment for this project (kcl, various other build tools, etc), built using nix + devenv.

4. What is your KCL components version? (Required)

❯ kcl version
0.11.0-linux-amd64
❯ kcl-language-server version
Version: 0.11.1-c020ab3eb4b9179219d6837a57f5d323
Platform: x86_64-unknown-linux-gnu
GitCommit: d8964b29170ba28c98a31b561a2d9525112d1f30

[He1pa]

I haven't found out how to set option like ignore in the notify watcher. I'll do some workarounds to avoid this error.

[Stinjul]

Hi, could we maybe get a flag or something to turn the file watcher off until there is a way to filter folders?
I'm also using nix+devenv and kcl-language-server takes a very long time (~10 minutes in one case) to start because of this.

I also found this open PR which I think adds the needed functionality in notify: notify-rs/notify#632