#2386 Fix 'unreadable file error' in watch mode after a save in vscode

[Anonymous]

Originally created by: marcosbozzani

This fix detects 'File to read not found or unreadable' and 'File to import not found or unreadable' errors that occasionally happens after a file save in Visual Studio Code when node-sass is running on watch mode.

If those errors are detected, a retry mechanism is applied. It verifies that the file actually exists and limits the maximum number of retries to 1000. In my local tests, it usually takes less than 5 retries. The limit is there as a safety measure to prevent infinite recursion and the value is high enough for those cases where the machine is really slow or it has to access a storage with high latency, like a remote one.

Those errors happen with 'node-sass (watch mode)', 'chokidar + node-sass' and 'node-sass-chokidar (watch mode)' too.

It is also possible to change the retry mechanism for one with exponential backoff. For example:

Change this code:

if (isFileUnreadable(error) && retries < 1000) {
      retries++;
      sass.render(renderOptions, renderCallback);
}

For this one:

if (isFileUnreadable(error) && retries < 4) {
      retries++;
      setTimeout(() => sass.render(renderOptions, renderCallback), Math.pow(retries, 5));
}

Related issues:
https://github.com/sass/node-sass/issues/1894
https://github.com/sass/node-sass/issues/2022
https://github.com/Microsoft/vscode/issues/20491
https://github.com/facebook/create-react-app/issues/2531
https://github.com/michaelwayman/node-sass-chokidar/issues/14
https://github.com/michaelwayman/node-sass-chokidar/issues/22
https://stackoverflow.com/questions/50395998/vscode-wont-work-with-filewatchers

[Anonymous]

Originally posted by: xzyfer

I don't believe this is the correct place for this patch. The issue is the
lack of atomic saving in some editors. The correct place to patch this is
in the watchers themselves i.e. gaze, and chokidar. Node Sass is moving to
chokidar which has better support for handling this situation.

On Fri., 18 May 2018, 2:52 pm Marcos, notifications@github.com wrote:

This fix detects 'File to read not found or unreadable' and 'File to
import not found or unreadable' errors that occasionally happens after a
file save in Visual Studio Code when node-sass is running on watch mode.

If those errors are detected, a retry mechanism is applied. It verifies
that the file actually exists and limits the maximum number of retries to
1000. In my local tests, it usually takes less than 5 retries. The limit is
there as a safety measure to prevent infinite recursion and the value is
high enough for those cases where the machine is really slow or it has to
access a storage with high latency, like a remote one.

Those errors happen with 'node-sass (watch mode)', 'chokidar + node-sass'
and 'node-sass-chokidar (watch mode)' too.

It is also possible to change the retry mechanism for one with exponential
backoff. For example:

Change this code:

if (isFileUnreadable(error) && retries < 1000) {
retries++;
sass.render(renderOptions, renderCallback);
}

For this one:

if (isFileUnreadable(error) && retries < 4) {
retries++;
setTimeout(() => sass.render(renderOptions, renderCallback), Math.pow(retries, 5));
}

Related issues:
[#1894] https://github.com/sass/node-sass/issues/1894
[#2022] https://github.com/sass/node-sass/issues/2022
Microsoft/vscode#20491 https://github.com/Microsoft/vscode/issues/20491
facebook/create-react-app#2531
https://github.com/facebook/create-react-app/issues/2531
michaelwayman/node-sass-chokidar#22
https://github.com/michaelwayman/node-sass-chokidar/issues/22

https://stackoverflow.com/questions/50395998/vscode-wont-work-with-filewatchers

You can view, comment on, or merge this pull request online at:

https://github.com/sass/node-sass/pull/2386
Commit Summary

• Fix 'unreadable file error' in watch mode after a save in vscode

File Changes

• M lib/render.js
  https://github.com/sass/node-sass/pull/2386/files#diff-0 (25)

Patch Links:

• https://github.com/sass/node-sass/pull/2386.patch
• https://github.com/sass/node-sass/pull/2386.diff

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[Anonymous]

Originally posted by: marcosbozzani

Sorry if I wasn't clear enough in the PR. I know it's not node-sass fault. Yet this cause a very annoying issue for node-sass users. This could serve as a temporary workaround that could be removed once the real issue was solved. It doesn't affect those editors that do that right thing and mitigate the problem until the other editors can be fixed.

Chokidar fails as well (chokidar + node-sass and node-sass-chokidar), as you can see in the related issues. 😕

I'm just sharing the solution that worked for me, so anyone can use it. 😉

If this is really not the right place for this patch, I'm sorry for the trouble. 😅

[Anonymous]

Originally posted by: maartenraes

@marcosbozzani worked for me by replacing the file localy, many thanks! 👍

[Anonymous]

Originally posted by: derek126

This would be great to have. This issue is very annoying.