Reduce allocations in the C# lexer ctor #76544
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The lexer ctor shows as about 0.5% of all allocations over the lifetime of the RoslynCodeAnalysisProcess in the csharp editing speedometer tests. There was already the concept of the LexerCache which had some pooling usage in it. This PR moves a couple other members to it to allow for their pooling. This PR is going to be marked as a draft PR until I can get some data from a test insertion indicating whether these changes improve allocations in the speedometer tests.
dotnet-issue-labeler
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Area-Compilers
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Test insertion: https://dev.azure.com/devdiv/DevDiv/_git/VS/pullrequest/599798 |
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Speedometer results look promising, going to promote out of draft mode. Allocations under Lexer.*ctor in IncPaths: |
ToddGrun
changed the title
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@dotnet/roslyn-compiler -- ptal |
AlekseyTs
reviewed
Dec 26, 2024
| @@ -24,6 +25,7 @@ public static SyntaxListBuilder Create() | |||
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| public void Clear() | |||
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| Array.Clear(_nodes, 0, Count); | |||
AlekseyTs
reviewed
Dec 26, 2024
| } | ||
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| internal void Free() | ||
| { | ||
| _keywordKindMap.Free(); | ||
| _keywordKindMap = s_keywordKindPool.Allocate(); |
AlekseyTs
reviewed
Dec 26, 2024
| @@ -70,6 +70,8 @@ internal enum XmlDocCommentStyle | |||
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| internal sealed partial class Lexer : AbstractLexer | |||
| { | |||
| private static readonly ObjectPool<LexerCache> s_lexerCachePool = new ObjectPool<LexerCache>(() => new LexerCache()); | |||
AlekseyTs
reviewed
Dec 26, 2024
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| private const int LeadingTriviaCacheInitialCapacity = 128; | ||
| private const int TrailingTriviaCacheInitialCapacity = 16; | ||
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| internal LexerCache() |
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Done with review pass (commit 1) |
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The lexer ctor shows as about 0.6% of all allocations over the lifetime of the RoslynCodeAnalysisProcess in the csharp editing speedometer tests.
There was already the concept of the LexerCache which had some pooling usage in it. This PR moves a couple other members to it to allow for their pooling.
Speedometer results look quite promising:
Allocations under Lexer.ctor in IncPaths reduced from 60 MB to 1.5 MB
Allocations under Lexer in IncPaths reduced from 1.57 GB to 1.36 GB