Skip to main content

How to detect heap allocations

A few weeks ago I talked about static anonymous functions and how they can help to limit the number of heap allocations when using lambdas. A colleague contacted me after this post with the question how to detect those allocations.

Great question! Let me share you some ways on how to do this.

Let me first give you a general answer and let’s then dive in 2 specific tools.

To discover excessive allocations when using lambdas you can use any memory profiler tool and look for allocations of *__DisplayClass* or various variants of Action* and Func*.

With this information, you already know what to look for.

Visual Studio Performance profiler

A first option to help you is the Performance Profiler in Visual Studio.

  • Change the Build type to Release.
  • Now go to Debug –> Performance Profiler…
  • There are multiple profiling targets available, but we want to use the .NET Object Allocation tracking option so select this check box.

  • Click the Start button to run the tool.

  • After closing the profiled application or clicking on Stop collection we can view all allocations on the Allocation tab

    More information: Analyze memory usage for .NET objects - Visual Studio (Windows) | Microsoft Learn

    Roslyn Clr Heap Allocation Analyzer

    Another option is the Roslyn based C# heap allocation diagnostic analyzer that can detect explicit and many implicit allocations like boxing, display classes a.k.a closures, implicit delegate creations, etc.

    It can be installed directly in your project as a NuGet package:

    dotnet add package ClrHeapAllocationAnalyzer

    As with any analyzer, it gives you inline hints:

    and warnings:

    If you want to see it in action, have a look at the following video:

    Remark: If you are using JetBrains Rider, you can achieve the same thing using the Heap Allocation Viewer plugin.

    Popular posts from this blog

    DevToys–A swiss army knife for developers

    As a developer there are a lot of small tasks you need to do as part of your coding, debugging and testing activities.  DevToys is an offline windows app that tries to help you with these tasks. Instead of using different websites you get a fully offline experience offering help for a large list of tasks. Many tools are available. Here is the current list: Converters JSON <> YAML Timestamp Number Base Cron Parser Encoders / Decoders HTML URL Base64 Text & Image GZip JWT Decoder Formatters JSON SQL XML Generators Hash (MD5, SHA1, SHA256, SHA512) UUID 1 and 4 Lorem Ipsum Checksum Text Escape / Unescape Inspector & Case Converter Regex Tester Text Comparer XML Validator Markdown Preview Graphic Color B

    Help! I accidently enabled HSTS–on localhost

    I ran into an issue after accidently enabling HSTS for a website on localhost. This was not an issue for the original website that was running in IIS and had a certificate configured. But when I tried to run an Angular app a little bit later on http://localhost:4200 the browser redirected me immediately to https://localhost . Whoops! That was not what I wanted in this case. To fix it, you need to go the network settings of your browser, there are available at: chrome://net-internals/#hsts edge://net-internals/#hsts brave://net-internals/#hsts Enter ‘localhost’ in the domain textbox under the Delete domain security policies section and hit Delete . That should do the trick…

    Azure DevOps/ GitHub emoji

    I’m really bad at remembering emoji’s. So here is cheat sheet with all emoji’s that can be used in tools that support the github emoji markdown markup: All credits go to rcaviers who created this list.