[Perf issue] Autocomplete is still slow

• I have searched through existing issues
• I have read through docs
• I have read FAQ

Info

• Platform: Win
• Vetur version: 0.19.4
• VS Code version: 1.33.1
• Typescript version: 3.2.4
• Use class style component
• Number of vue files: 71
• Number of ts files: 115
• Number of dependencies in package.json: 50

Problem

Autocomplete is still slow in class style component, I guess my project is just a medium size project.

[Trace - 00:05:00] Received response 'textDocument/documentLink - (163)' in 6970ms.
[Trace - 00:05:00] Received response 'textDocument/documentColor - (164)' in 6971ms.
[Trace - 00:05:00] Sending request 'textDocument/codeAction - (171)'.
[Trace - 00:05:00] Sending notification '$/cancelRequest'.
[Trace - 00:05:01] Received response 'textDocument/codeAction - (165)' in 8395ms.
[Trace - 00:05:01] Received notification 'textDocument/publishDiagnostics'.
[Trace - 00:05:02] Sending request 'textDocument/codeAction - (172)'.
[Trace - 00:05:02] Sending notification '$/cancelRequest'.
[Trace - 00:05:02] Received response 'textDocument/codeAction - (166)' in 7747ms.
[Trace - 00:05:02] Received response 'textDocument/codeAction - (167)' in 7144ms.
[Trace - 00:05:03] Received response 'completionItem/resolve - (168)' in 7358ms.
[Trace - 00:05:03] Received response 'textDocument/codeAction - (169)' in 7086ms.
[Trace - 00:05:04] Received response 'textDocument/codeAction - (170)' in 5819ms.
[Trace - 00:05:04] Received response 'textDocument/codeAction - (171)' in 4366ms.
[Trace - 00:05:05] Received response 'textDocument/codeAction - (172)' in 3401ms.

Here is the profile CPU-20190503T235912.zip

[tohkinzhu]

me too…If i use typescript in .vue file. But it’s fast in .ts file. I found that the more ts files, the slower the speed…(200+ .ts files in my project) There is no such problem with webstorm

[NoahStahl]

I spent some time debugging the extension code today and noticed a few things. I stepped through code while watching performance counters to isolate lines that cause the observed I/O spikes. So far, I think the performance impact is coming from interaction with the TS language server in ways that cause it to scan the entire project for all TS-related files. One example is this line:

https://github.com/vuejs/vetur/blob/7fa2ead6831f22beaf6dd0ec87ed888a1c7ed65f/server/src/modes/script/javascript.ts#L605

Every keystroke causes many of these calls, each of which causes a scan of the entire project file system (thousands of reads each time). Caching that result and reusing if possible would reduce the IO, rather than repeating every time.

Another way this seems to happen is any time the TS language server runs its createProgram function, which likewise scans and parses all TS files. This would be any function call into the TS service, like:

https://github.com/vuejs/vetur/blob/7fa2ead6831f22beaf6dd0ec87ed888a1c7ed65f/server/src/modes/script/javascript.ts#L147

Those calls result in createProgram invocations internally that generate lots of IO.

I came across some discussion that might be related, where caching the TS server instance data somehow is suggested as a workaround:

https://github.com/typescript-eslint/typescript-eslint/issues/243

Hope the helps. It’s my first time in the code, so if I’m off I apologize.