7 ms·

Exploring the .NET Core Runtime

251 points by matthewwarren 8y ago

giancarlostoro 8y ago
C# was the first language after Visual Basic 6 that I learned the most seriously, and after .NET Core I got the most excited about C#. I love that I don't have to reach to Java anymore to go cross platform, or wonder if Mono will support my .NET project or not. In fact, thanks to .NET Core they made .NET Standard so I know if and how my project will run on a modern version of Mono. I also love that people are doing write ups about the source of .NET Core and it's internals.
- matthewwarren 8y ago
  > I also love that people are doing write ups about the source of .NET Core and it's internals. Me too! BTW, if you want more on the same topic check out http://mattwarren.org/2018/07/12/Presentations-and-Talks-covering-.NET-Internals/ http://mattwarren.org/2018/07/12/Presentations-and-Talks-cov... and http://mattwarren.org/2018/01/22/Resources-for-Learning-about-.NET-Internals/ http://mattwarren.org/2018/01/22/Resources-for-Learning-abou...
  - phoenix24 8y ago
    thank you for the links, this is amazing!
revskill 8y ago
Installing .NET stacks including Runtime, SQL Server is a nightmare to me. When an error occurs during installation process, you got stuck , hopeless and depressed. Hey MS, fix your installation process first.
- taspeotis 8y ago
  .NET Desktop/Full Framework’s been fine after some initial missteps when they first bundled it in the OS with Vista. .NET Core has self contained deployments so you can bundle it with your app in a .zip. For development or continuous integration SQL Server comes in a container now.
  - flukus 8y ago
    > .NET Desktop/Full Framework’s been fine after some initial missteps when they first bundled it in the OS with Vista They first bundled (1.0) with xp, and every OS since. I don't know why they bothered considering practically every app has had to bundle newer versions with the installer. They could have at least pushed newer versions with windows update.
    - thomasz 8y ago
      It was so absurd that only a windiv power play against devdiv can adequately explain it.
- titanix2 8y ago
  Did you try SQL Server in a container? It's way more easy to get up and running than installing it on Windows. https://hub.docker.com/r/microsoft/mssql-server https://hub.docker.com/r/microsoft/mssql-server
  - revskill 8y ago
    No, docker is a cancer to me, Docker has the same problem with installation on Windows now. SO if i use Docker to install MS stack, i have two problems now.
- voltagex_ 8y ago
  Where are you getting stuck? What errors?
  - revskill 8y ago
    I don't remember because i don't use MS stack anymore for a long time. Just an alert to fix past issues for everyone that needs it.
    - svick 8y ago
      How is an issue you had a long time ago relevant now? And why do you say "fix X first" if you don't even know whether it's still a problem?
- pknopf 8y ago
  The build scripts (for coreclr, corehost, corefx) are a mess. I worked on getting the build working for Yocto, and there were so many things done differently all over the place. They need a single team to go through their entire build process, top-to-bottom. Don't get me wrong though, I worked to integrate it into Yocto because I love .NET/C#, but the build system needs a lot of love.
  - matthewwarren 8y ago
    I don't know if it solves your specific scenario, but I do know that there's been some work done in this area. See https://github.com/dotnet/source-build#net-core-build-scripts https://github.com/dotnet/source-build#net-core-build-script... and https://github.com/dotnet/arcade#arcade https://github.com/dotnet/arcade#arcade
- kyllo 8y ago
  What platform/OS? Are you installing from a package manager, from binary, or from source?
  - revskill 8y ago
    I used Windows before.
- equasar 8y ago
  Never heard about this kind of issues, can you share specific ones you had?
  - lovich 8y ago
    seconded. I've never had an installation fail, but I have always installed on windows. I'm curious if its due to installing on other OS's that aren't supported as well, as I am looking to jump stacks and thought .net core would have been a hassle free transition to a new OS at least
    - merb 8y ago
      installing .net core on linux is easier than on windows (they create native linux packages, so apt install ... or yum install is enough or docker, whatever they provides so much these days), and macos provides a pkg file, which is just click trough.
- skc 8y ago
  Always been piss easy for me, and I've done it for years now.
- bpicolo 8y ago
  You can run Postgres with .NET these days no problem. http://www.npgsql.org/efcore/ http://www.npgsql.org/efcore/
bad_user 8y ago
I was never impressed with .NET, I always considered it inferior to the JVM and its ecosystem in terms of runtime capabilities, tooling and open source available, however .NET Core moving to an open source model is super exciting, F# looks cool and I'm happy that Java finally has true competition. Also Matt Warren's blog is super cool.
- lwansbrough 8y ago
  Java is not an example of a forward thinking language anymore. It has lagged behind C# in every major feature pretty much since C# arrived in 2000. The JVM has had solid performance improvements since forever, and may still be faster than the CLR, but the JVM still has some pretty glaring shortcomings coming from the .NET world. For example, Java generics (and their underlying implementation in the JVM) suffer from type erasure which makes for an awful developer experience in many scenarios. Java/JVM's story for asynchronous code is also pretty pathetic. This is stuff I don't even think about anymore when writing C# but I groan every time I have to do any "modern" programming in Java.
  - bad_user 8y ago
    My opinion is from the other side of the fence ... type erasure is perceived as a weakness of Java, however I believe it is one of JVM's best features, because it didn't cripple its runtime for other languages, this being one of the reasons for why other languages have been flourishing on the JVM (that and the tooling and the open source culture). To understand why, we need to talk about 2 separate things: --- 1. Specialization is important for performance and when speaking of .NET, specialization for value types is subsumed in type erasure, but that's not necessarily the case. You can have compiler-driven or even runtime-driven specialization without reification. In Scala for example we've had the "@specialize" annotation for a long time, with the compiler being able to specialize generic code just fine. It's not perfect, a better implementation eventually happened in Miniboxing [1] but it withered away due to lack of interest and the ongoing work happening in Dotty / Scala 3 and its newer TASTY distribution format, which should make specialization easier to accomplish. Also there is on-going work to bring value types to the JVM and it's happening: http://mail.openjdk.java.net/pipermail/valhalla-spec-experts/2018-May/000618.html http://mail.openjdk.java.net/pipermail/valhalla-spec-experts... That said having specialization is pretty cool for fine control of the memory layout and Java developers have to resort to a lot of unsafe hacks for achieving the same thing. But if that cost was paid such that languages like Scala or Haskell could happen on top of the JVM, until they figure out how to do it such that everybody benefits, I think it was a cost worth paying. Also consider that the lack of specialization forced the JVM 's engineers to get creative in other areas. For example the JVM has always been great at inlining code at runtime, even for megamorphic call sites. And the new GraalVM has super impressive abilities to eliminate boxing at runtime, which works for dynamic languages too: https://www.graalvm.org/ https://www.graalvm.org/ --- 2. Reification is in fact about adding info about type parameters at runtime. This aids in using reflection to make a difference between List<int> and List<string>, but people miss the forest from the trees. As a matter of fact such reflection is only needed because languages like Java or C# have very weak static type systems, compared with other languages in the ML family. With an expressive type system, you never need reflection capabilities. In Haskell for example the question of whether something is a List<string> or List<int> never, ever happens. In Scala you sometimes need it, but much rarely and you can get it via a compiler-generated `ClassTag`, which is actually a much better approach, because it makes it clear in the signature, this being compile-time reflection. People also like being able to do "new T", however that need completely goes away via proper support for type classes, which both Haskell and Scala have, this being another special purpose band-aid. And reification is actually a bad feature to have in the runtime, because it makes it hard for languages to support higher-kinded types, or to build dynamic languages. F# does not do higher-kinded types and is less expressive for that reason than OCaml, Scala or Haskell and the primary reason for why it doesn't do higher-kinded types is because it would have to do type erasure by itself, thus forgoing the performance benefits and the interoperability it has with C#. Ironically it is support for higher-kinded types in a language that increases its expressive capabilities to the point that you no longer need runtime reflection. In other words ... you're blaming Java for not having a band-aid that happened in C# due to their static type system being basically unsound and thus needing runtime guards and reflection. You quickly get over this once you'll start using a more expressive language ;-) [1] http://scala-miniboxing.org/ http://scala-miniboxing.org/
Traubenfuchs 8y ago
How much of the old CLR is in the new .net core runtime /CoreCLR? I once read CLR via C# and it was difficult but amazing. Is all of the knowledge in that book now worthless? What about the IL, is the IL still the same?
- tybit 8y ago
  They forked the CLR, cleaned it up, added cross platform support and open sourced it, so a lot would still be relevant would be my guess. The IL has remained unchanged other than possibly a tweak or two to support newer features like non nullable references.
  - matthewwarren 8y ago
    Interesting fact, when they forked the CLR, they actually started with the Silverlight code base. See https://channel9.msdn.com/Blogs/dotnet/NET-Foundations-2015-03-04 https://channel9.msdn.com/Blogs/dotnet/NET-Foundations-2015-... (somewhere near the beginning) I guess it makes sense. Before .NET Core, Silverlight was the most x-plat version of the Microsoft .NET Runtime(s) (excluding Xamarin/Mono), so it would've been a good starting point.
eksemplar 8y ago
Do people really use .NET core, and if so, why? We’ve been a C# house for several years, decades really, and I’ve always preferred it to JAVA so I’m actually excited for Core. But we rarely use it. Not because it’s not great, rather because we’re more productive with flask or Django. For Core to really make sense for us, it’d would have to stop being so damn low level, but I guess that maybe it can’t without sacrificing too much efficiency. More importantly it needs better libraries for things that aren’t “built-in”. I can certainly see why .NET developers welcome it, because they finally have good cross platform ability. At least until they need to do authentication on a non-standard SAML token, that though easily supported by ADFS but is a bitch in any .NET setup. I know we aren’t most use cases, being the public sector and running a gazillion different tech stacks at once, but .NET has never played well once you stepped outside it’s comfortzone and it’s always been so low level that writing library extensions were a bitch. And that may have worked out, so far, but I just don’t see why people stick with it when there are more productive alternatives. I say productive, because I don’t think .NET core is lacking technically, but delivering solutions on time and with minimum maintenance requirements afterward is just easier in python or JAVA and I’d imagine others as well. But maybe I’m missing something?
- pepper_sauce 8y ago
  What's your definition of "low level"? You keep using that word, I do not think it means what you think it means
  - eksemplar 8y ago
    It’s having to explicitly tell the computer what you want. C# is obviously not C, but it’s not python either. By the time we have an app running in Django, we’re not even finished with Entity modelling in a Core web-api. I do think stuff like Blazor.Net is promising, but we’re not a technology company, we support thousands of employees who only care about how digitisation can make their lives easier as fast and as stable as possible. .NET isn’t the best at that, at least not for us. Dont get me wrong, I don’t dislike .NET Core, it think it’s great, I just don’t see how it benefits me.
memsom 8y ago
The "two" books mentioned that were written by Serge Lidin are basically the same book, the latter is just an updated version. So really, there's only one book with two editions.
- matthewwarren 8y ago
  Ah, I didn't realise that, thanks for the info

251 points by matthewwarren 8y ago

C# was the first language after Visual Basic 6 that I learned the most seriously, and after .NET Core I got the most excited about C#. I love that I don't have to reach to Java anymore to go cross platform, or wonder if Mono will support my .NET project or not. In fact, thanks to .NET Core they made .NET Standard so I know if and how my project will run on a modern version of Mono. I also love that people are doing write ups about the source of .NET Core and it's internals.

matthewwarren 8y ago
> I also love that people are doing write ups about the source of .NET Core and it's internals. Me too! BTW, if you want more on the same topic check out http://mattwarren.org/2018/07/12/Presentations-and-Talks-covering-.NET-Internals/ http://mattwarren.org/2018/07/12/Presentations-and-Talks-cov... and http://mattwarren.org/2018/01/22/Resources-for-Learning-about-.NET-Internals/ http://mattwarren.org/2018/01/22/Resources-for-Learning-abou...
- phoenix24 8y ago
  thank you for the links, this is amazing!

revskill 8y ago

Installing .NET stacks including Runtime, SQL Server is a nightmare to me. When an error occurs during installation process, you got stuck , hopeless and depressed. Hey MS, fix your installation process first.

taspeotis 8y ago
.NET Desktop/Full Framework’s been fine after some initial missteps when they first bundled it in the OS with Vista. .NET Core has self contained deployments so you can bundle it with your app in a .zip. For development or continuous integration SQL Server comes in a container now.
- flukus 8y ago
  > .NET Desktop/Full Framework’s been fine after some initial missteps when they first bundled it in the OS with Vista They first bundled (1.0) with xp, and every OS since. I don't know why they bothered considering practically every app has had to bundle newer versions with the installer. They could have at least pushed newer versions with windows update.
  - thomasz 8y ago
    It was so absurd that only a windiv power play against devdiv can adequately explain it.
titanix2 8y ago
Did you try SQL Server in a container? It's way more easy to get up and running than installing it on Windows. https://hub.docker.com/r/microsoft/mssql-server https://hub.docker.com/r/microsoft/mssql-server
- revskill 8y ago
  No, docker is a cancer to me, Docker has the same problem with installation on Windows now. SO if i use Docker to install MS stack, i have two problems now.
voltagex_ 8y ago
Where are you getting stuck? What errors?
- revskill 8y ago
  I don't remember because i don't use MS stack anymore for a long time. Just an alert to fix past issues for everyone that needs it.
  - svick 8y ago
    How is an issue you had a long time ago relevant now? And why do you say "fix X first" if you don't even know whether it's still a problem?
pknopf 8y ago
The build scripts (for coreclr, corehost, corefx) are a mess. I worked on getting the build working for Yocto, and there were so many things done differently all over the place. They need a single team to go through their entire build process, top-to-bottom. Don't get me wrong though, I worked to integrate it into Yocto because I love .NET/C#, but the build system needs a lot of love.
- matthewwarren 8y ago
  I don't know if it solves your specific scenario, but I do know that there's been some work done in this area. See https://github.com/dotnet/source-build#net-core-build-scripts https://github.com/dotnet/source-build#net-core-build-script... and https://github.com/dotnet/arcade#arcade https://github.com/dotnet/arcade#arcade
kyllo 8y ago
What platform/OS? Are you installing from a package manager, from binary, or from source?
- revskill 8y ago
  I used Windows before.
equasar 8y ago
Never heard about this kind of issues, can you share specific ones you had?
- lovich 8y ago
  seconded. I've never had an installation fail, but I have always installed on windows. I'm curious if its due to installing on other OS's that aren't supported as well, as I am looking to jump stacks and thought .net core would have been a hassle free transition to a new OS at least
  - merb 8y ago
    installing .net core on linux is easier than on windows (they create native linux packages, so apt install ... or yum install is enough or docker, whatever they provides so much these days), and macos provides a pkg file, which is just click trough.
skc 8y ago
Always been piss easy for me, and I've done it for years now.
bpicolo 8y ago
You can run Postgres with .NET these days no problem. http://www.npgsql.org/efcore/ http://www.npgsql.org/efcore/

bad_user 8y ago

I was never impressed with .NET, I always considered it inferior to the JVM and its ecosystem in terms of runtime capabilities, tooling and open source available, however .NET Core moving to an open source model is super exciting, F# looks cool and I'm happy that Java finally has true competition. Also Matt Warren's blog is super cool.

lwansbrough 8y ago
Java is not an example of a forward thinking language anymore. It has lagged behind C# in every major feature pretty much since C# arrived in 2000. The JVM has had solid performance improvements since forever, and may still be faster than the CLR, but the JVM still has some pretty glaring shortcomings coming from the .NET world. For example, Java generics (and their underlying implementation in the JVM) suffer from type erasure which makes for an awful developer experience in many scenarios. Java/JVM's story for asynchronous code is also pretty pathetic. This is stuff I don't even think about anymore when writing C# but I groan every time I have to do any "modern" programming in Java.
- bad_user 8y ago
  My opinion is from the other side of the fence ... type erasure is perceived as a weakness of Java, however I believe it is one of JVM's best features, because it didn't cripple its runtime for other languages, this being one of the reasons for why other languages have been flourishing on the JVM (that and the tooling and the open source culture). To understand why, we need to talk about 2 separate things: --- 1. Specialization is important for performance and when speaking of .NET, specialization for value types is subsumed in type erasure, but that's not necessarily the case. You can have compiler-driven or even runtime-driven specialization without reification. In Scala for example we've had the "@specialize" annotation for a long time, with the compiler being able to specialize generic code just fine. It's not perfect, a better implementation eventually happened in Miniboxing [1] but it withered away due to lack of interest and the ongoing work happening in Dotty / Scala 3 and its newer TASTY distribution format, which should make specialization easier to accomplish. Also there is on-going work to bring value types to the JVM and it's happening: http://mail.openjdk.java.net/pipermail/valhalla-spec-experts/2018-May/000618.html http://mail.openjdk.java.net/pipermail/valhalla-spec-experts... That said having specialization is pretty cool for fine control of the memory layout and Java developers have to resort to a lot of unsafe hacks for achieving the same thing. But if that cost was paid such that languages like Scala or Haskell could happen on top of the JVM, until they figure out how to do it such that everybody benefits, I think it was a cost worth paying. Also consider that the lack of specialization forced the JVM 's engineers to get creative in other areas. For example the JVM has always been great at inlining code at runtime, even for megamorphic call sites. And the new GraalVM has super impressive abilities to eliminate boxing at runtime, which works for dynamic languages too: https://www.graalvm.org/ https://www.graalvm.org/ --- 2. Reification is in fact about adding info about type parameters at runtime. This aids in using reflection to make a difference between List<int> and List<string>, but people miss the forest from the trees. As a matter of fact such reflection is only needed because languages like Java or C# have very weak static type systems, compared with other languages in the ML family. With an expressive type system, you never need reflection capabilities. In Haskell for example the question of whether something is a List<string> or List<int> never, ever happens. In Scala you sometimes need it, but much rarely and you can get it via a compiler-generated `ClassTag`, which is actually a much better approach, because it makes it clear in the signature, this being compile-time reflection. People also like being able to do "new T", however that need completely goes away via proper support for type classes, which both Haskell and Scala have, this being another special purpose band-aid. And reification is actually a bad feature to have in the runtime, because it makes it hard for languages to support higher-kinded types, or to build dynamic languages. F# does not do higher-kinded types and is less expressive for that reason than OCaml, Scala or Haskell and the primary reason for why it doesn't do higher-kinded types is because it would have to do type erasure by itself, thus forgoing the performance benefits and the interoperability it has with C#. Ironically it is support for higher-kinded types in a language that increases its expressive capabilities to the point that you no longer need runtime reflection. In other words ... you're blaming Java for not having a band-aid that happened in C# due to their static type system being basically unsound and thus needing runtime guards and reflection. You quickly get over this once you'll start using a more expressive language ;-) [1] http://scala-miniboxing.org/ http://scala-miniboxing.org/

Traubenfuchs 8y ago

How much of the old CLR is in the new .net core runtime /CoreCLR? I once read CLR via C# and it was difficult but amazing. Is all of the knowledge in that book now worthless? What about the IL, is the IL still the same?

tybit 8y ago
They forked the CLR, cleaned it up, added cross platform support and open sourced it, so a lot would still be relevant would be my guess. The IL has remained unchanged other than possibly a tweak or two to support newer features like non nullable references.
- matthewwarren 8y ago
  Interesting fact, when they forked the CLR, they actually started with the Silverlight code base. See https://channel9.msdn.com/Blogs/dotnet/NET-Foundations-2015-03-04 https://channel9.msdn.com/Blogs/dotnet/NET-Foundations-2015-... (somewhere near the beginning) I guess it makes sense. Before .NET Core, Silverlight was the most x-plat version of the Microsoft .NET Runtime(s) (excluding Xamarin/Mono), so it would've been a good starting point.

eksemplar 8y ago

Do people really use .NET core, and if so, why? We’ve been a C# house for several years, decades really, and I’ve always preferred it to JAVA so I’m actually excited for Core. But we rarely use it. Not because it’s not great, rather because we’re more productive with flask or Django. For Core to really make sense for us, it’d would have to stop being so damn low level, but I guess that maybe it can’t without sacrificing too much efficiency. More importantly it needs better libraries for things that aren’t “built-in”. I can certainly see why .NET developers welcome it, because they finally have good cross platform ability. At least until they need to do authentication on a non-standard SAML token, that though easily supported by ADFS but is a bitch in any .NET setup. I know we aren’t most use cases, being the public sector and running a gazillion different tech stacks at once, but .NET has never played well once you stepped outside it’s comfortzone and it’s always been so low level that writing library extensions were a bitch. And that may have worked out, so far, but I just don’t see why people stick with it when there are more productive alternatives. I say productive, because I don’t think .NET core is lacking technically, but delivering solutions on time and with minimum maintenance requirements afterward is just easier in python or JAVA and I’d imagine others as well. But maybe I’m missing something?

pepper_sauce 8y ago
What's your definition of "low level"? You keep using that word, I do not think it means what you think it means
- eksemplar 8y ago
  It’s having to explicitly tell the computer what you want. C# is obviously not C, but it’s not python either. By the time we have an app running in Django, we’re not even finished with Entity modelling in a Core web-api. I do think stuff like Blazor.Net is promising, but we’re not a technology company, we support thousands of employees who only care about how digitisation can make their lives easier as fast and as stable as possible. .NET isn’t the best at that, at least not for us. Dont get me wrong, I don’t dislike .NET Core, it think it’s great, I just don’t see how it benefits me.

memsom 8y ago

The "two" books mentioned that were written by Serge Lidin are basically the same book, the latter is just an updated version. So really, there's only one book with two editions.

matthewwarren 8y ago
Ah, I didn't realise that, thanks for the info