Localized resources in the CLI adds 53 MB on disk and increases time-to-main by ~50%

The CLI today includes resources for all languages for not only itself but all of its dependencies, including Roslyn, MSBuild, NuGet, and VSTest. This happens regardless of the locale of the machine the CLI is installed on.

The inclusion of all these resources results in:

• ~53 MB of on-disk space (~24% of the CLI size on disk total)
• 48 KB of the dotnet.deps.json file
• An increase in time-to-main for the CLI of ~50% (due to size of deps.json file)
  • Measured on my desktop, removing the resources entries from the deps.json reduced time-to-main for the CLI from ~75ms to ~48ms

It doesn’t seem as though there’s any benefit to including all language resources in every install (i.e. I don’t personally get a benefit from all language resources other than English being installed).

The impact on time-to-main is particularly interesting with regards to the effort to improve the CLI performance for inner-loop scenarios in .NET 6 (see https://github.com/dotnet/msbuild/issues/5876), offering a saving to the floor for the CLI’s time-to-main of at least 50% in local testing.

Here’s the results of a manual analysis of the resources files in the CLI installation I found today (using version 6.0.100-preview.2.21118.12 installed on Windows via the nightly installer):

Path	Size on disk (Bytes)	KB	MB
root	17,461,248	17,052	16.65
DotnetTools\dotnet-watch\6.0.100-preview.1.21118.15\tools\net6.0\any	483,328	472	0.46
Extensions	1,122,304	1,096	1.07
FSharp	5,742,592	5,608	5.48
Microsoft\Microsoft.NET.BuildExtensions\tools\net6.0	512,000	500	0.49
Roslyn	266,240	260	0.25
Roslyn\bincore	9,486,336	9,264	9.05
Sdks\Microsoft.NET.Sdk\analyzers	3,592,192	3,508	3.43
Sdks\Microsoft.NET.Sdk\codestyle\cs	1,245,184	1,216	1.19
Sdks\Microsoft.NET.Sdk\codestyle\vb	1,134,592	1,108	1.08
Sdks\Microsoft.NET.Sdk\tools\net6.0	512,000	500	0.49
Sdks\Microsoft.NET.Sdk\tools\net472	512,000	500	0.49
Sdks\Microsoft.NET.Sdk.Publish\tools\net6.0	921,600	900	0.88
Sdks\Microsoft.NET.Sdk.Publish\tools\net472	921,600	900	0.88
Sdks\Microsoft.NET.Sdk.Razor\tasks\net6.0	5,103,616	4,984	4.87
Sdks\Microsoft.NET.Sdk.WindowsDesktop\tools\netcoreapp2.1	593,920	580	0.57
Sdks\Microsoft.NET.Sdk.WindowsDesktop\tools\net472	593,920	580	0.57
Sdks\NuGet.Build.Tasks.Pack\CoreCLR	2,011,136	1,964	1.92
Sdks\NuGet.Build.Tasks.Pack\Desktop	2,011,136	1,964	1.92
TestHost	1,716,224	1,676	1.64
Resources Total	55,943,168	54,632	53.35
CLI Total	288,780,288	282,012	275.40
Resources as a portion of overall CLI size on disk	24%

Note that we added support for selecting specific languages for satellite resources in 2.x: https://github.com/dotnet/sdk/issues/774

Additionally, in my local testing I noted that completely removing the CLI’s deps.json file didn’t seem to impact the operation of the CLI itself. The commands I tried all continued to work perfectly well when the deps.json file was deleted.

While putting this table together I noticed a lot of duplication. You can see a bunch of size values appear identically a number of times as different components bring in the same dependencies, which bring in their resources again. It might be useful for that to investigated separately in the interest of simplifying the layout and thus install time and disk cost of the CLI.

[vitek-karas]

@mateoatr and I are working on a host change which would forego file probes for pretty much all the files in the .deps.json - maybe even the resource files (those are tricky though). While not as good as removing parts of the .deps.json completely, it should help a LOT. So maybe if we combine all of these together it will give us enough of a win for 6.

[marcpopMSFT]

Tracking as part of the optimize SDK size .net 7 planning document.