maui-inprocess-benchmark

MauiBenchDemo — driving a .NET MAUI UI from BenchmarkDotNet, in-process

This is a small, self-contained repro that shows how to micro-benchmark a live .NET MAUI user interface with BenchmarkDotNet, without any cross-process communication.

The benchmark and the running MAUI app live in the same process, so the benchmark can poke at real views, view models, bindings, layout and navigation in a tight loop. There is no UI-automation driver, no Appium/WinAppDriver, no pipe or socket — and therefore none of the per-call latency that cross-process automation adds.

Built for .NET 10, targeting Windows (WinUI 3) and Mac Catalyst.

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TL;DR

# Windows
cd src/MauiBenchDemo
dotnet build -c Release -f net10.0-windows10.0.19041.0 -p:WindowsPackageType=None

# Run as a normal demo app (a clickable window):
./bin/Release/net10.0-windows10.0.19041.0/win-x64/MauiBenchDemo.exe

# Run the benchmarks in-process (self-quits when done):
$env:RUN_BENCHMARKS = '1'
./bin/Release/net10.0-windows10.0.19041.0/win-x64/MauiBenchDemo.exe

Results print to a console window and are also written to BenchmarkDotNet.Artifacts/ next to the executable.

See docs/RUNNING.md for the Mac Catalyst steps and more detail, docs/MAC-RUNBOOK.md for a full step-by-step Mac guide, and docs/HOW-IT-WORKS.md for the design.

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The idea in one picture

+---------------------------- single OS process ----------------------------+
|                                                                           |
|   UI thread (WinUI on Windows / Mac Catalyst on macOS)                     |
|        MAUI host  ->  App  ->  MainPage (REAL, on-screen views)            |
|             ^                              |                               |
|             |  Dispatch(work)             |  result / exception           |
|             |                              v                               |
|   BenchmarkDotNet engine thread  --(blocking in-memory marshal)--          |
|        [Benchmark] BuildViewTree / UpdateBinding / LayoutPass / ...        |
|                                                                           |
+---------------------------------------------------------------------------+

The app is the benchmark host. A launch switch tells it to start BenchmarkDotNet (using the InProcess toolchain) on a background thread once the window is up. Each benchmark hands its UI work to the UI thread through a tiny dispatcher helper and blocks for the result.

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What's in the box

src/MauiBenchDemo/
  MainPage.xaml(.cs)              Demo home page (bound VM + buttons, incl. "Run benchmarks")
  Views/ItemsPage.xaml(.cs)      CollectionView bound to an ObservableCollection
  Views/DetailPage.xaml(.cs)     Navigation target
  ViewModels/                    INotifyPropertyChanged view models
  Models/Item.cs                 Trivial data record
  Benchmarks/
    UiDispatcher.cs              Blocking "run this on the UI thread" helper
    BenchmarkHost.cs             Holds references to the live app objects
    UiBenchmarks.cs              The 5 sample [Benchmark] methods
    BenchmarkLauncher.cs         Starts BenchmarkDotNet in-process, then quits
docs/
  HOW-IT-WORKS.md                Architecture + how to add your own benchmarks
  RUNNING.md                     Per-platform build/run instructions

The sample benchmarks

Benchmark	What it exercises
BuildViewTree	Constructing a fresh view tree (view object creation)
UpdateBindingAndLayout	Changing a bound property + a layout pass
LayoutPass	Measure + arrange of the realized page (layout engine only)
MutateBoundList	Add/remove on a collection bound to a CollectionView
NavigatePushPop	Navigate to a page and back (handler create/teardown)

Example output (Windows, Debug, ShortRun)

BenchmarkDotNet v0.15.8, .NET 10.0.9, Toolchain=InProcessNoEmitToolchain

| Method                 | Mean        | Allocated |
|----------------------- |------------:|----------:|
| BuildViewTree          |  2,040.4 us | 706.28 KB |
| UpdateBindingAndLayout |    155.9 us |   1.69 KB |
| LayoutPass             |     98.8 us |    1.4 KB |
| MutateBoundList        |  5,071.2 us |  82.56 KB |
| NavigatePushPop        | 49,035.9 us | 286.16 KB |

(Numbers are illustrative — use Release + Job.Default for real measurements; see docs/RUNNING.md.)

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Adapting this to your app

You only need to copy the four files in Benchmarks/ and follow the pattern:

1. In your first page's constructor, set UiDispatcher.Instance = Dispatcher; and stash a reference to the live page (BenchmarkHost.Home = this;).
2. Call BenchmarkLauncher.AutoRunWhenReady(this); so --benchmark works.
3. In UiBenchmarks, replace the method bodies with the operations you care about, always wrapping UI work in UiDispatcher.Run(...).

Full walkthrough in docs/HOW-IT-WORKS.md.

Prerequisites

• .NET 10 SDK
• The MAUI workload: dotnet workload install maui
• Windows: Windows 10 19041+; macOS: a Mac with Xcode for the Mac Catalyst head