Non recursive watch requests are not refcounted

[taronlee]

Does this issue occur when all extensions are disabled?: Yes/No

• VS Code Version: Version: 1.68.0 (user setup)
  Commit: 4af164e
  Date: 2022-06-08T11:44:16.822Z
  Electron: 17.4.7
  Chromium: 98.0.4758.141
  Node.js: 16.13.0
  V8: 9.8.177.13-electron.0

• OS Version: Windows_NT x64 10.0.17134

Steps to Reproduce:
We have .gbs.conf file and watch this file using FileSystemWatcher.

this.fsProvider = workspace.createFileSystemWatcher(
      new RelativePattern(homedir(), '.gbs.conf')
);

this.disposable.push(
  this.fsProvider.onDidChange(async e => {
    console.log(`onDidChange event`);        
  })
);

when I set .gbs.conf as pattern parameter, onDidChange event fires twice each time.

[vscodenpa]

Thanks for creating this issue! It looks like you may be using an old version of VS Code, the latest stable release is 1.68.0. Please try upgrading to the latest version and checking whether this issue remains.

Happy Coding!

[bpasero]

File events are not guaranteed to be single, so it is totally expected that you get 2 or even more events. For example, file writes via node.js are often a truncate first and then a write, which can emit 2 events.

How do you change the file? Is this native windows, or WSL?

[taronlee]

How do you change the file? Is this native windows, or WSL?
=> WSL, I am using remote-ssh. (windows -> build server (ubuntu))

in our project, we use FileSystemWatcher in many case.
but only in this case ( file name starts with .), emit 2 events each time.

[bpasero]

Do you see the same issue when using Windows file system without WSL?

[taronlee]

Hello,
I tested it on Windows without WSL, but still emit 2 events each time.

onDidChange event
onDidChange event

[taronlee]

when I set **.gbs.conf as pattern parameter, onDidChange event fires just one each time.

But I'm worried that it doesn't exactly match the file name.

I think setting .gbs.conf as pattern parameter should work just fine too.

[bpasero]

And the 2 events are reported when you use VSCode to make a change to the file?

[taronlee]

yes, I made a change to the file using VSCode.
It doesn't matter where I make a change.

[bpasero]

I tested this with bare node.js and get the same result, so this is standard node.js behaviour:

const fs = require("fs");

fs.watch("C:\\Users\\bpasero\\Desktop\\empty\\new.js", console.log);

fs.writeFileSync("C:\\Users\\bpasero\\Desktop\\empty\\new.js", 'Hello World');

When installing a recursive file watcher (via complex glob pattern, e.g. including **), we install a different file watcher that is probably not impacted: https://github.com/parcel-bundler/watcher

Unfortunately that watcher does not support flat (non-recursive) file watching, otherwise we would never use node.js watcher. I had asked for this in parcel-bundler/watcher#92

Closing as designed / upstream, sorry.

[bpasero]

Nevermind, while it is true that node.js emits 2 events out of the box, we actually have logic to deduplicate events in a time frame of 50ms.

The issue here is different:

• the extension installs a watcher using the parent folder and the file name as pattern
• when you open the file in vscode, we also install a watcher to react to changes in the editor
• as such, any change you do ends up with 2 events

Let's move into #153009 as a more general issue. For now there is no good solution other than deduplicating on your end, sorry.