Choosing between CoreCLR and Mono

[stefan-sf-ibm]

Is there any way to choose between CoreCLR and Mono? I tried adding UseMonoRuntime to my csproj file without luck, i.e., CoreCLR is still used.

I'm asking because ultimately I would like to run a couple of BenchmarkDotnet tests while switching between CoreCLR and Mono.

I'm using dotnet 6.0 RC1 on x64.

[danmoseley]

@steveisok

[steveisok]

@stefan-sf-ibm Can you share a branch / files?

[stefan-sf-ibm]

I started of a hello world build by doing dotnet new console and added UseMonoRuntime to the csproj file:

<Project Sdk="Microsoft.NET.Sdk">

  <PropertyGroup>
    <OutputType>Exe</OutputType>
    <TargetFramework>net6.0</TargetFramework>
    <ImplicitUsings>enable</ImplicitUsings>
    <Nullable>enable</Nullable>
    <UseMonoRuntime>true</UseMonoRuntime>
  </PropertyGroup>

</Project>

Running MONO_ENV_OPTIONS="-v -v -v -v" dotnet run doesn't output anything. Running the same while using the systems mono binary prints a lot of debug information. Thus I assumed that the prior command still uses CoreCLR instead of Mono. Did I miss something?

[steveisok]

Ah, looks like this will run using the shared framework, which will not contain any of the mono parts. It's something that is technically possible, but since all mono configurations are self contained (w/ dotnet publish), we haven't had the need to go all the way.

Can you try dotnet publish and run your executable from there? You should get the mono runtime at that point.

[stefan-sf-ibm]

Running dotnet publish and afterwards MONO_ENV_OPTIONS="-v -v -v -v" ./bin/Debug/net6.0/publish/tt still doesn't print any debug output.

[steveisok]

I should have asked earlier. What OS?

[stefan-sf-ibm]

I'm on Fedora 33

[PathogenDavid]

I'm asking because ultimately I would like to run a couple of BenchmarkDotnet tests while switching between CoreCLR and Mono.

BenchmarkDotNet automatically rebuilds your benchmark and launches that instead of using the one you built. (I've never looked into why it does this, but I've always assumed it has to do with how it instruments things for benchmarking.) The situation might be that you're starting the BenchmarkDotNet runner as Mono but it's starting the actual benchmarks with CoreCLR.

If your goal is to compare benchmarks between CoreCLR and Mono, you should probably use BenchmarkDotNet's built-in support for doing so.

[stefan-sf-ibm]

@PathogenDavid thanks for the hint! I will give it a try :)