We can often hear that allocation of objects is “cheap” in .NET. I fully support this sentence because the most important part is its continuation – allocation is cheap but allocating a lot of objects will hit you back as sooner or later garbage collector will kick in and start messing around. Thus, the fewer allocations, the better.

However, I would like to add a few words about “allocation is cheap” itself. This is true to some extent because the typical path of objects allocation is indeed really fast. So-called bump a pointer technique is most often used. It consists of the following simple steps:

  • it uses so-called allocation pointer as an address of a newly created object
  • it increases allocation pointer by the requested size (so next object will be created there

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Zero Garbage Collector on .NET Core

Starting from .NET Core 2.0 coupling between Garbage Collector and the Execution Engine itself have been loosened. Prior to this version, the Garbage Collector code was pretty much tangled with the rest of the CoreCLR code. However, Local GC initiative in version 2.0 is already mature enough to start using it. The purpose of the exercise we are going to do is to prepare Zero Garbage Collector that replaces the default one.

Zero Garbage Collector is the simplest possible implementation that in fact does almost nothing. It only allows you to allocate objects, because this is obviously required by the Execution Engine. Created objects are never automatically deleted and theoretically, no longer needed memory is never reclaimed. Why one would be interested in such a simple GC implementation? There are at least two reasons:Continue reading

Trace Compass

.NET Core on Linux is still very fresh in 2017. First production deployments are just beginning to emerge. Consequently, development on this platform is only beginning to show up. There is a lack of knowledge and good practices related to virtually every aspect of the existence of this environment. One of them is monitoring and diagnostic aspect. How can we monitor and analyze the health of our application?

The easiest way of getting tracing data is by using official perfcollect bash script and then using Perfview on Windows to analyze this recorded data. This approach has some drawbacks. The main one is are fairly limited analysis results available in PerfView. The second, less burdensome, is the need for Windows to… analyze Linux data. Recently Sasha Goldstein has created a lot of valuable material on this subject and I invite you to review the list posted at the end of this post.

I would like to present another diagnostic option here. This is using the free Eclipse Trace Compass tool. Continue reading

Note: This is a first entry of a new series about Microsoft .NET CLR internals. I encourage you to ask – the most interesting questions will become a similar posts in the future! This one was inspired by Angelika Piątkowska.

How does Object.GetType() really work?

Extending this question: How an object knows what type it is? Is it the compiler or the runtime that knows that? How this is related to the CLR? As C# is statically and strongly typed, maybe the method call GetType() does not really exist, and the compiler can replace it with the appropriate result already at compile time?Continue reading



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