appsettingsschema.json is in use by another process

[JamesNK]

Is there an existing issue for this?

• I have searched the existing issues

Describe the bug

I see this error inside VS:

Severity	Code	Description	Project	File	Line	Suppression State	Details
Error (active)		The process cannot access the file 'C:\Users\jamesnk\AppData\Local\Temp\appsettingsschema.json' because it is being used by another process.	Keycloak.AppHost, ProxylessEndToEnd.AppHost, TestShop.AppHost	C:\Program Files\Microsoft Visual Studio\2022\IntPreview\MSBuild\Microsoft\VisualStudio\WebTools.Aspire\Microsoft.WebTools.Aspire.targets	47		

Expected Behavior

No response

Steps To Reproduce

No response

Exceptions (if any)

No response

.NET Version info

No response

Anything else?

No response

[afscrome]

I just saw this too after upgrading a project to 9.0. It stuck around in VS until I restarted VS, and I haven't seen it since.

[DamianEdwards]

I see this a bunch too

[JamesNK]

@eerhardt Is this something you know about?

[eerhardt]

I've only seen this in our repo, and not in a normal application. I believe it is coming from VS and not anything we can do in dotnet/aspire.

cc @vijayrkn

[JakeRadMSFT]

If anyone hits this again ...

Can you search in Associated Handles for the file path? Please report back what processes have a hold on the file.

[danmoseley]

@bradygaster should this go back to backlog? It seems not actionable, given nobody's posted they've been able to repro.

I bet it's VS and I"ll keep an eye out for it too.

[JamesNK]

I searched for the handle after getting this in VS and didn't get any results:

[danmoseley]

Moving to backlog as this isn't actionable.

[afscrome]

I have just seen this in a real aspire app, so I don't think it's limited to this repo.

The error in VS right immediately after I updated my Directory.Packages.props from

    <PackageVersion Include="Aspire.Hosting" Version="9.1.0-preview.1.25111.2" />
    <PackageVersion Include="Aspire.Hosting.AppHost" Version="9.0.0" />
    <PackageVersion Include="Aspire.Hosting.Redis" Version="9.0.0" />
    <PackageVersion Include="Aspire.Hosting.Testing" Version="9.0.0" />

to

    <PackageVersion Include="Aspire.Hosting" Version="9.1.0-preview.1.25111.2" />
    <PackageVersion Include="Aspire.Hosting.AppHost" Version="9.1.0-preview.1.25111.2" />
    <PackageVersion Include="Aspire.Hosting.Redis" Version="9.1.0-preview.1.25111.2" />
    <PackageVersion Include="Aspire.Hosting.Testing" Version="9.1.0-preview.1.25111.2" />

I've managed to reproduce this a few times (say 2-3 times out of every 20) and managed to capture a procmon trace of this - I can share this privately to help troubleshoot.

Trace was taken with the following filter to keep noise down:

I can see that msbuild.exe is the only process that has tried to access %USERPROFILE%\AppData\Local\Temp\appsettingsschema.json, with the conflict coming with

With the following error showing up in VS:

The process cannot access the file '%USERPROFILE%\AppData\Local\Temp\appsettingsschema.json' because it is being used by another process.

[afscrome]

Based on the error, this seems to be coming from the following in Microsoft.WebTools.Aspire.targets

  <Target Name="GenerateCombinedAppSettingsSchemaTarget"
          DependsOnTargets="GenerateCombinedComponentSchemaTarget"
          Condition=" '@(JsonSchemaSegment)' != '' "
          BeforeTargets="CompileDesignTime"
          Inputs="$(SchemaGenIncrementalBuildInputs);$(JsonSchemaCombinedFilePath)"
          Outputs="$(AppSettingsJsonSchemaCombinedFilePath)">
    <GenerateCombinedAppSettingsSchema
      AppSettingJsonSchemaFilePath="$(AppSettingJsonSchemaLoadFilePath)"
      ComponentJsonSchemaCombinedFilePath="$(JsonSchemaCombinedFilePath)"
      AppSettingsJsonSchemaCombinedFilePath="$(AppSettingsJsonSchemaCombinedFilePath)">
    </GenerateCombinedAppSettingsSchema>
    <Message Text="Generating appsettingsschema" />
  </Target>

Inside Microsoft.WebTools.Aspire.MSBuild.GenerateCombinedAppSettingsSchema.DownloadBaseAppSettingsJsonSchema(), there is the following code

string path = Path.Combine(Path.GetTempPath(), "appsettingsschema.json");
System.IO.File.WriteAllText(path, end);

If multiple projects are building in parallel, and hit this at the same time, one or more will fail. That would suggest this problem is more likely to occur with more projects in the solution, which would explain why we see this regularly within the aspire solution, but not so frequently elsewhere.

This download should either be reworked to be downloaded once per solution rather than once per project, or use a unique filename to avoid conflicts when multiple projects build at once.

I can't find this code in the repo, so I assume this is something Visual Studio specific.

[DamianEdwards]

So this looks like a "simple" parallel build issue? i.e. if multiple projects are using client integrations that contribute JSON schema and they get built in parallel, you can hit this issue because the file name/path is shared. Shouldn't that file be unique per project?

[DamianEdwards]

FYI @JakeRadMSFT potential lead on the issue.

[DamianEdwards]

Ah I see this is the download of the base schema, not the generation of the unique combined schema.