vscode emmet extension does not work anymore

[akosyakov]

Uncaught Error: Cannot find module 'vscode-emmet-helper'

Error: Cannot find module 'vscode-emmet-helper'
    at Function.Module._resolveFilename (/internal/modules/cjs/loader.js:582)
    at Function.Module._load (/internal/modules/cjs/loader.js:508)
    at Function.module._load (/workspace/theia/packages/plugin-ext-vscode/lib/node/plugin-vscode-init.js:98)
    at Module.require (/internal/modules/cjs/loader.js:637)
    at require (/internal/modules/cjs/helpers.js:22)
    at Object.<anonymous> (/tmp/vscode-unpacked/vscode-builtin-emmet-0.1.0.tgz/package/dist/extension.js:1)
    at n (/tmp/vscode-unpacked/vscode-builtin-emmet-0.1.0.tgz/package/dist/extension.js:1)
    at Object.t.getEmmetHelper (/tmp/vscode-unpacked/vscode-builtin-emmet-0.1.0.tgz/package/dist/extension.js:1)
    at t.DefaultCompletionItemProvider.provideCompletionItemsInternal (/tmp/vscode-unpacked/vscode-builtin-emmet-0.1.0.tgz/package/dist/extension.js:1)
    at t.DefaultCompletionItemProvider.provideCompletionItems (/tmp/vscode-unpacked/vscode-builtin-emmet-0.1.0.tgz/package/dist/extension.js:1)
    at /vs/editor/editor.main.js:12536
/vs/editor/editor.main.js:12536 Uncaught Error: a.updateExtensionsPath is not a function

TypeError: a.updateExtensionsPath is not a function
    at c (/tmp/vscode-unpacked/vscode-builtin-emmet-0.1.0.tgz/package/dist/extension.js:1)
    at Object.t.getEmmetHelper (/tmp/vscode-unpacked/vscode-builtin-emmet-0.1.0.tgz/package/dist/extension.js:1)
    at t.DefaultCompletionItemProvider.provideCompletionItemsInternal (/tmp/vscode-unpacked/vscode-builtin-emmet-0.1.0.tgz/package/dist/extension.js:1)
    at t.DefaultCompletionItemProvider.provideCompletionItems (/tmp/vscode-unpacked/vscode-builtin-emmet-0.1.0.tgz/package/dist/extension.js:1)
    at CompletionAdapter.provideCompletionItems (/workspace/theia/packages/plugin-ext/lib/plugin/languages/completion.js:36)
    at /workspace/theia/packages/plugin-ext/lib/plugin/languages.js:149
    at LanguagesExtImpl.withAdapter (/workspace/theia/packages/plugin-ext/lib/plugin/languages.js:121)
    at LanguagesExtImpl.$provideCompletionItems (/workspace/theia/packages/plugin-ext/lib/plugin/languages.js:149)
    at RPCProtocolImpl.doInvokeHandler (/workspace/theia/packages/plugin-ext/lib/api/rpc-protocol.js:207)
    at RPCProtocolImpl.invokeHandler (/workspace/theia/packages/plugin-ext/lib/api/rpc-protocol.js:192)
    at /vs/editor/editor.main.js:12536

In order to reproduce, install it from https://registry.npmjs.org/@theia/vscode-builtin-emmet/-/vscode-builtin-emmet-0.2.1.tgz

[akosyakov]

Something wrong with require function in the plugin host process, it cannot find a module although it is there. @evidolob @benoitf maybe you can have an idea which change could cause it. Trying to debug it in the meantime.

[benoitf]

maybe unload of the cache #5514 ?

[akosyakov]

@benoitf thanks, checking

[akosyakov]

@benoitf Why do we need to mess around with internal details on require function? I wonder why it was introduced? Someone redeploys another version of the same extension without reloading the window?

[akosyakov]

yes, reverting #5514 helps

[akosyakov]

Unfortunately, i could not find any test cases in PR introduced cache clean up or reasoning of introducing it. @benoitf @evidolob please provide, we need to know how we can change it without breaking

[benoitf]

it's on che side inside containers, extensions are restarted in the same process (this is why there is a need of proper clean-up as in fact there are some memory leaks)
#4931

[akosyakov]

@benoitf the reason is this line: https://github.com/theia-ide/theia/blob/3587c237cacc638dc54ec19dc3eaa755c2e69fb5/packages/plugin-ext/src/hosted/node/plugin-host-rpc.ts#L115

Is it really necessary? If we remove it would you be able to verify that there are no memory leaks? It would be good what other contributors can test with vanilla Theia.

Also code looks a bit strange. I've looked at npm modules which do unloading, they are traversing module tree starting from the root and only delete loaded modules from the root instead of going over the whole cache, so they never touch unrelated records. Could we use decache instead: https://github.com/dwyl/decache/blob/master/decache.js#L26?

[akosyakov]

I could not find here nodejs/node#8443 an advice to purge module exports.

[akosyakov]

Unloading is not related, see #5760 (comment)