November 2020 – TooSlowException

Month: November 2020

Why .NET Diagnostics Expert is not just yet-another-online-course?

November 26, 2020 by Konrad Kokosa·1 Comment

Testing shows the presence of errors in a product, but “cannot prove that there are no defects” – you probably know that quote. I remember so many hours spent on debugging those little, mean bugs hidding deeply in the code edge cases. But what’s worse, I remember even more hours trying to understand and reproduce an error that happens only in production environment. Here’s the first top 5 most popular issues I’ve met during last years:

app hangs due to deadlocks (in the app or external library)
memory issues like memory leaks, long GC pauses or high CPU usage due to the GC
swallowed exception preventing some logic, with no logs available
threading issues like thread-pool starvation
intermittent errors due to the resources shortage, like running out of sockets or file handles

BTW. And what’s yours top 5?

6 less popular facts about C# 9 records

November 19, 2020 by Konrad Kokosa·5 Comments

A lot of C# 9-related content is around. Very often, records are mentioned as one of the most interestning new features. So, while we can find A LOT of buzz around them, I wanted to provide a distilled set of facts typically not presented when describing them.

Fact #1. You can use them in pre-.NET 5

Records has been announced as C# 9 feature (and thus .NET 5), and it is the officially supported way. But you can “not officialy” use most C# 9 features in earlier frameworks, as they don’t need the new runtime support. So, if being not “officially supported” does not bother you too much, just set proper LangVersion in csproj and you are (almost) done:

<PropertyGroup>
   <TargetFramework>netcoreapp3.1</TargetFramework>
   <LangVersion>9</LangVersion>
</PropertyGroup>

<TargetFramework>netcoreapp3.1</TargetFramework>

</PropertyGroup>

Trying to compile super typical example like the following:

public record Person
{
   public string FirstName { get; init; }
   public string LastName { get; init; }
}

public record Person

{

public string FirstName { get; init; }

public string LastName { get; init; }

}

will still not compile, complaining about the lack of mysterious IsExternalInit type:

Error CS0518 Predefined type 'System.Runtime.CompilerServices.IsExternalInit' is not defined or imported

1	Error CS0518 Predefined type 'System.Runtime.CompilerServices.IsExternalInit' is not defined or imported

To be funny, the workaround is just to define it in your project (exactly as it is in the newer CoreLib, shipped with .NET 5):

namespace System.Runtime.CompilerServices
{
   public class IsExternalInit{}
}

namespace System.Runtime.CompilerServices

{

public class IsExternalInit{}

}

BTW, IsExternalInit is not required for the record usage by itself, but for init as discussed in https://github.com/dotnet/runtime/issues/34978 and https://github.com/dotnet/runtime/pull/37763. So if creating mutable records is ok, no need for that.

Sidenote: If you are interested what more you can “not officially” use, look at Using C# 9 outside .NET 5 #47701 discussion.Continue reading