Revert "Revert "reduce memory allocation when a project instance is created from immutable project cache state"" #12513
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…reated f…" This reverts commit da45290.
JanProvaznik
approved these changes
Sep 11, 2025
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Pull Request Overview
This PR reverts the revert of memory allocation optimizations when creating ProjectInstance from immutable project cache state. The primary purpose is to reduce memory usage during project instance creation by introducing lazy-loading patterns and more efficient collection converters.
Key changes include:
- Introduces
LazyStringValuedListfor deferred string list initialization - Implements
ImmutableProjectMetadataCollectionConverterandImmutableProjectPropertyCollectionConverterfor optimized collection handling - Updates
TranslatorHelpers.csto supportIReadOnlyDictionary<string, string>parameters
Reviewed Changes
Copilot reviewed 23 out of 23 changed files in this pull request and generated 7 comments.
Show a summary per file
| File | Description |
|---|---|
src/Shared/TranslatorHelpers.cs |
Adds new overload for translating IReadOnlyDictionary<string, string> and refactors existing ImmutableDictionary method to use the new implementation |
src/Build/Microsoft.Build.csproj |
Updates project file to include new collection converter classes and removes old converter implementations |
src/Build/Instance/ProjectItemInstance.cs |
Changes metadata storage from ImmutableDictionary to IReadOnlyDictionary with lazy conversion and optimized property access |
src/Build/Instance/ProjectInstance.cs |
Implements lazy import path loading and optimized property collection handling for immutable project sources |
src/Build/Instance/ImmutableProjectCollections/LazyStringValuedList.cs |
New class implementing lazy-initialized, immutable string list for import paths |
src/Build/Instance/ImmutableProjectCollections/ImmutableProjectPropertyCollectionConverter.cs |
New converter for optimized property collection handling with direct value retrieval |
src/Build/Instance/ImmutableProjectCollections/ImmutableProjectMetadataCollectionConverter.cs |
New converter for metadata collections with lazy dictionary conversion |
src/Build/Instance/ImmutableProjectCollections/ImmutableGlobalPropertiesCollectionConverter.cs |
Enhanced with IValueDictionaryConverter interface support |
src/Build/Collections/RetrievableEntryHashSet/IRetrievableUnescapedValuedEntryHashSet.cs |
New interface for direct unescaped value retrieval without object allocation |
src/Build/Collections/PropertyDictionary.cs |
Enhanced with unescaped value retrieval and read-only dictionary conversion |
src/Build/Collections/IValueDictionaryConverter.cs |
New interface for specialized property dictionaries |
| Test files | Multiple test files implementing mock objects for testing the new functionality |
src/Build/Instance/ImmutableProjectCollections/ImmutableProjectMetadataCollectionConverter.cs
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Yes, it was proved that these changes didn't caused the regression. |
rainersigwald
approved these changes
Sep 11, 2025
MichalPavlik
deleted the
revert-12510-revert-12249-dev/lifengl/reduceImmutableProjectInstanceAllocation
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Reverts the revert of #12510 :) Original PR #12249