Why createdump.exe is needed to do "dotnet publish"?

[mingtong]

I am trying to publish a .NET 5 trimmed App(upgrading from .NET Core 3.1), with the command
"dotnet publish -c Release --force -r win-x86 --self-contained true "xxxcsproj" /p:PublishTrimmed=true"
I found the following DLLs are needed.

• System.Formats.Asn1.dll
• Microsoft.Windows.SDK.NET.dll
• WinRT.Runtime.dll
• api-ms-win-core-console-l1-2-0.dll
• createdump.exe

But I am quite confused why createdump.exe is needed to run?
Is it for .NET 5 RC2 to collect dump file and will not be needed in Release version?

And, is there a way to reduce the size of "Microsoft.Windows.SDK.NET.dll", it's nearly 30MB.

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[vitek-karas]

@sbomer Do you remember the rules around native library trimming in self-contained apps? Did createdump.exe slipped through?

As for Microsoft.Windows.SDK.NET.dll that's basically all of WinUI APIs I think (not an expert in this area). PublishTrimmed=true will only remove entire assemblies, it does not remove parts of assemblies. It can be asked to do so, but it's very likely to break the application unless the assemblies in question are prepared for it. I don't think WinUI has done any work to be trim-friendly, so I would not try to do it (very likely to break the app).
@AaronRobinsonMSFT might know a bit more about the WinUI side of things.

Please note that trimming is still an experimental feature. Be sure to thoroughly test the trimmed app.

[AaronRobinsonMSFT]

Microsoft.Windows.SDK.NET.dll is for WinUI and other WinRT scenarios. We did not start investigating support for trimming though. Attempting that is possible but I agree with @vitek-karas that the probability is low it will be successful.

/cc @Scottj1s

[sbomer]

We don't remove native libraries at the moment. The OOB package had some support for it but we didn't productize it. There's at least one existing issue about it at dotnet/linker#2853. IIRC one of the open questions was how to handle the windows native compat shims - they may or may not be required, depending on the target windows version.

[mingtong]

We don't remove native libraries at the moment. The OOB package had some support for it but we didn't productize it. There's at least one existing issue about it at dotnet/linker#2853. IIRC one of the open questions was how to handle the windows native compat shims - they may or may not be required, depending on the target windows version.

Sorry, I don't quite clear for "createdump.exe“, is it expected at this moment?

[vitek-karas]

Sorry for the confusion.

Short version: yes, it is expected at this moment. I would think you can safely remove the file if you really want to - it might break some dump debugging scenarios, but it should not be needed to run the app itself.

The trimming process splits the files in the output into 3 categories:

• Managed assemblies (which may be trimmed)
• Native libraries - in reality this is all of native executables, so createdump.exe falls into this category
• Other - typically data files and so on

As noted above there has been some history around trying to remove some of the files in the native libraries category when trimming. Apparently none of the prototypes made it into the product, so we intentionally leave the native binaries as is.

[mingtong]

Sorry for the confusion.

Short version: yes, it is expected at this moment. I would think you can safely remove the file if you really want to - it might break some dump debugging scenarios, but it should not be needed to run the app itself.

The trimming process splits the files in the output into 3 categories:

• Managed assemblies (which may be trimmed)
• Native libraries - in reality this is all of native executables, so createdump.exe falls into this category
• Other - typically data files and so on

As noted above there has been some history around trying to remove some of the files in the native libraries category when trimming. Apparently none of the prototypes made it into the product, so we intentionally leave the native binaries as is.

Thank you, it's clear for the categories.

Actually, the "createdump.exe" is needed to start my service(my App).
If I manually delete the "createdump.exe" in the running folder, and restart my service, it will report the following error:

Message: Error:
An assembly specified in the application dependencies manifest (xxx.deps.json) was not found:
package: 'runtimepack.Microsoft.NETCore.App.Runtime.win-x86', version: '5.0.0-rc.2.20475.5'
path: 'createdump.exe'

[vitek-karas]

You're right - it is still needed. This is unfortunate - the app actually doesn't need the file for anything, but it's listed as "being part of the app" and the host checks that everything which is part of the app is present, so it fails.

[mingtong]

You're right - it is still needed. This is unfortunate - the app actually doesn't need the file for anything, but it's listed as "being part of the app" and the host checks that everything which is part of the app is present, so it fails.

OK, the last question is, will it be removed in .NET 5 release? or .NET 6?
I found somebody put it in the .NET 6.0 milestone.

p.s. after answer this, you can choose to CLOSE or any other actions for this issue.

[agocke]

Yeah I put it in the 6.0 milestone because I don't think we should require it in the deps.json if it's unused. It may still be useful to copy to the output, but if users should be able to remove it if they want