Slow intellisense when workspace contains a DSC module

[dan-escott]

System Details

• Operating system name and version: Windows 7 x64
• VS Code version: 1.3.1.0
• PowerShell extension version: 1.13.0
• Output from $PSVersionTable:

Name Value

---

PSVersion 5.1.14409.1005
PSEdition Desktop
PSCompatibleVersions {1.0, 2.0, 3.0, 4.0...}
BuildVersion 10.0.14409.1005
CLRVersion 4.0.30319.42000
WSManStackVersion 3.0
PSRemotingProtocolVersion 2.3
SerializationVersion 1.1.0.1

Issue Description

I'm finding intellisense incredibly slow in some circumstances (often several tens of seconds). This also affects the time take for the great new code lens stuff to appear. I have quite a large repo, but by trial and error I found that knocking out all the DSC modules makes things blindingly fast. Adding even one DSC module back in makes things noticeably slower. I tried third party DSC modules (xPSDesiredStateConfirugation or xWebAdministration) and the behaviour's the same.

Attached Logs

The logs below are from two vscode workspaces: one has a third-party MySQL module, and the other has that module plus xPSDesiredStateConfiguration version 6.4.0.0. All I am doing is opening the MySQL module file and waiting for the code lens to appear in front of the first function. You can see from the timing that there's a 8-second lag before line 1537 of the version with DSC.

logs.zip

[daviwil]

Thanks @dandiddy! I'll take a look.

[kapilmb]

This is somewhat related to #869 - whenever a script contains Import-DSCResource keyword, parsing seems to slow down significantly.

[zachChilders]

Is there any update on this? We're working on a very DSC intensive project and VSCode has become almost unusably slow in the last month or so. vscode-Powershell Version 1.5.1 VSCode Version 1.18.1

[chriskuech]

This issue is causing many significant problems, as we've grown to rely significantly on correct linting for PSScriptAnalyzer issue resolution and this issue can deceptively create false errors. @dandiddy cited 8-second lag; however, my team has seen significantly higher lag and I believe that the linter has actually timed out.

Is there any update on this issue?

[TylerLeonhardt]

@rkeithhill I saw your example over in #869. Do you think the slow Invoke-ScriptAnalyzer would affect intellisense at all? Or would those two pieces be separate?

[rkeithhill]

When I analyze the OP's log file, it seems like the noticeable delay is for code lens resolve response:

Id Method                      ElapsedMSecs
-- ------                      ------------
   textDocument/didOpen                1000
0  initialize                             0
1  powerShell/getVersion                  0
2  textDocument/codeAction                0
3  textDocument/codeLens                  0
4  textDocument/documentSymbol            0
5  textDocument/codeAction                0
6  textDocument/codeLens                  0
7  textDocument/documentSymbol            0
8  textDocument/codeAction                0
9  codeLens/resolve                    4000

#9 is a resolve references message which uses the ReferencesCodeLensProvider in PSES. That looks be using parsing and not PSSA from a quick peruse.

[SeeminglyScience]

DSC uses thread static fields for caching keywords and CIM classes. We may need to check documents for DSC related commands/keywords before parsing. If we find any, we can either get on the interactive pipeline thread before attempting to parse, or possibly even dedicate a separate thread to just parsing.

For reference, here's the the test to see if DSC modules need to be loaded. Things really slow down if this test fails, importing modules and possibly even running Get-Module -ListAvailable.

[SydneyhSmith]

we recently published an update which has addressed a number of underlying architectural issues, would you mind giving it a try and letting us know if you are still hitting this issue?