Reduce allocations in AnalyzerDriver.TryExecuteSymbolEndActions#79855
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ToddGrun merged 2 commits intodotnet:mainfrom Sep 11, 2025
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The completedAnalyzers array was using an ArrayBuilder and would commonly exceed the ArrayBuilder reuse size threshold, preventing array reuse. Instead, just use an IA.Builder pool directly for pooling purposes. This allocation was showing up as abou 0.6% of allocations during completion scenarios in the razor cohosting speedometer test.
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@dotnet/roslyn-compiler -- This is ready for review now. |
CyrusNajmabadi
approved these changes
Aug 26, 2025
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@dotnet/roslyn-compiler for 2nd review |
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@dotnet/roslyn-compiler -- still need a 2nd review |
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@dotnet/roslyn-compiler -- still need a 2nd review |
AlekseyTs
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Sep 10, 2025
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| var success = true; | ||
| var completedAnalyzers = ArrayBuilder<DiagnosticAnalyzer>.GetInstance(); | ||
| var completedAnalyzers = s_diagnosticAnalyzerPool.Allocate(); |
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Are we actually changing the type used here?
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It was changing the type, but I'll go ahead and make the change that you requested from the other PR to use an ObjectPool<ArrayBuilder> even though I'm definitely not a fan.
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@AlekseyTs -- Does commit 2 work for you? |
333fred
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Sep 11, 2025
* upstream/main: (233 commits) Extensions: add SyntaxGenerator support and AssociatedExtensionImplementation API (dotnet#80170) Fix error when hoisting a non-ref call (dotnet#80138) Ensure that refkinds are rewritten for complex methods (dotnet#79916) Revert Do not go through the workspace to access services DefiniteAssignmentPass.MarkFieldsUsed - avoid infinite recursion due to generic substitution (dotnet#80135) Reduce allocations in AnalyzerDriver.TryExecuteSymbolEndActions (dotnet#79855) RefSafetyAnalysis: Fix handling of nested deconstruction utilizing modern extensions (dotnet#80231) Extensions: adjust rewriting of anonymous type property symbols (dotnet#80211) Extensions: Move public APIs into INamedTypeSymbol (dotnet#80230) Extensions: improve error recovery in older language versions (dotnet#80206) Fall back to `dotnet exec` if apphost does not exist (dotnet#80153) Update dependencies from https://github.com/dotnet/dotnet build 282708 (dotnet#80228) Add a workaround for microsoft/vs-mef#620 Revert "FailFast if the MEF composition is clearly broken" switch from windows combobox to visualstudio combobox (dotnet#80219) Update System.Text.Json in packages which use 4.12 Roslyn (dotnet#80197) add flags to unblock CI (dotnet#80222) Move static members to another type - qualifies static member references in the moved members (dotnet#80178) Fix broken link for C# 14 lambda parameter modifiers ...
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The completedAnalyzers array was using an ArrayBuilder and would commonly exceed the ArrayBuilder reuse size threshold, preventing array reuse. Instead, just use an IA.Builder pool directly for pooling purposes.
This allocation was showing up as about 0.6% of allocations during completion scenarios in the razor cohosting speedometer test.
Test insertion: https://dev.azure.com/devdiv/DevDiv/_git/VS/pullrequest/662551
Numbers from the speedometer run with this change look good, DiagnosticAnalyzer[] allocations went from about 1.0% of total allocations down to about 0.1%.