[Perf] Lazy-initialize _triggerSpecificity dictionary on BindableObject - #34133
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StephaneDelcroix merged 2 commits intoFeb 23, 2026
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Fixes #34131 Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
simonrozsival
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Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
This was referenced Feb 19, 2026
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MartyIX
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Feb 20, 2026
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| internal ushort _triggerCount = 0; | ||
| internal Dictionary<TriggerBase, SetterSpecificity> _triggerSpecificity = new Dictionary<TriggerBase, SetterSpecificity>(); | ||
| internal Dictionary<TriggerBase, SetterSpecificity> _triggerSpecificity; |
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Would it work to add
#nullable enable
internal Dictionary<TriggerBase, SetterSpecificity>? _triggerSpecificity;
#nullable disable?
Or would it still cascade to more and more changes?
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That should work, but I don't think it has high value right now. We should let copilot annotate the whole class/codebase at some point.
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Pull request overview
This PR optimizes memory allocation in BindableObject by lazy-initializing the _triggerSpecificity dictionary, which is only used by the small fraction of objects (<5%) that actually have triggers attached. This reduces per-instance allocations for the vast majority of MAUI UI elements.
Changes:
- Removed eager initialization of
_triggerSpecificitydictionary inBindableObject - Added null-safe operations at all three access points in
TriggerBase(attach, detach, condition changed) - Added comprehensive benchmarks to measure allocation improvements for objects without triggers
Reviewed changes
Copilot reviewed 3 out of 3 changed files in this pull request and generated no comments.
| File | Description |
|---|---|
| src/Controls/src/Core/BindableObject.cs | Removed eager = new Dictionary<...>() initializer from _triggerSpecificity field |
| src/Controls/src/Core/Interactivity/TriggerBase.cs | Added null-coalescing assignment on attach, conditional access on detach and condition query |
| src/Core/tests/Benchmarks/Benchmarks/BindableObjectAllocBenchmarker.cs | New benchmark file covering multiple performance issues including trigger dictionary allocation (#34131) |
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LGTM from my review. I don't see blocking issues; this looks good to merge as-is.
StephaneDelcroix
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Feb 23, 2026
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February 23, 2026 11:07
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It would be very helpful if you could test the resulting artifacts from this PR and let us know in a comment if this change resolves your issue. Thank you!
Fixes #34131
Description
The
Dictionary<TriggerBase, SetterSpecificity>field_triggerSpecificitywas eagerly allocated on everyBindableObjectinstance, but fewer than 5% of objects ever use triggers. This PR makes it lazy-initialized on first use.Changes
BindableObject.cs— remove eager= new Dictionary<...>()initializerTriggerBase.cs— null-safe access at 3 call sites (??=on attach,?.on detach,?.TryGetValueon condition changed)