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dotnet run of hello world takes way too long

See original GitHub issue

Reported by @migueldeicaza

Steps to reproduce

dotnet new console
dotnet build
dotnet run

Expected behavior

dotnet run executes fast, nearly the same as calling dotnet <pathToDll>

Actual behavior

dotnet run is slow, about 3 seconds on my machine. It’s consistently this slow, even when it doesn’t need to rebuild.

It appears that run is calling msbuild twice before actually running the app:

Can’t we have a fast-path here that bypasses MSBuild? It seems like we’ve optimized for incremental build via the run command which I’m not sure is really the primary workflow for run (but I may be wrong).

Issue Analytics

State:
Created 6 years ago
Reactions:30
Comments:60 (28 by maintainers)

Top GitHub Comments

18reactions

omajidcommented, Sep 7, 2017

I believe dotnet run --no-build will help here. Maybe it should be the default.

7reactions

DamianEdwardscommented, Mar 9, 2021

We’re investigating CLI performance for the commands frequently used during development as part of .NET 6 and we definitely expect to get improvements to this very common scenario of running a simple app via dotnet run.

As it stands today, using a nightly build of .NET 6.0-preview.3, a dotnet run on a “Hello, World!” console app takes about 1.3-1.4 seconds on my machine, after a warm-up run or two. Running the app directly takes ~60ms, so the dotnet run overhead is practically the entire time, which is mostly spent in the the execution of the restore and build itself.

Progress on this work can be followed at https://github.com/dotnet/msbuild/issues/5876

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