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dotnet / efcore

EF Core is a modern object-database mapper for .NET. It supports LINQ queries, change tracking, updates, and schema migrations.
https://docs.microsoft.com/ef/
MIT License
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Partial fix to #35053 - Is EF9 slower than EF8? #35128

Closed maumar closed 3 days ago

maumar commented 5 days ago

Don't use Expression.Invoke in ValueComparer.ObjectEqualsExpression. ValueComparer now contains the information on how to build an expression representing Equals(object, object), which uses Expression.Invoke. We found this to be a major performance problem in some scenarios (e.g. include collection navigation) where that expression is executed large number of times by the result coordinator, as it is part of the parent/outer/selfIdentifierValueComparers. We actually know the lambda expression that is invoked in advance, so it's much more efficient to just remap the arguments and inline the lambda body into the ObjectEqualsExpression result.

Benchmark results:

ef 8

Method Async Mean Error StdDev Op/s Gen0 Gen1 Allocated
PredicateMultipleIncludes False 147.2 ms 2.63 ms 2.46 ms 6.793 4000.0000 3000.0000 26.24 MB
PredicateMultipleIncludes True 159.1 ms 3.00 ms 2.95 ms 6.287 5500.0000 3000.0000 34.47 MB

ef 9 without this change

Method Async Mean Error StdDev Op/s Gen0 Gen1 Allocated
PredicateMultipleIncludes False 322.6 ms 0.97 ms 0.86 ms 3.099 13000.0000 6000.0000 79.48 MB
PredicateMultipleIncludes True 344.9 ms 6.79 ms 6.67 ms 2.899 14000.0000 7000.0000 87.72 MB

ef 9 with this change

Method Async Mean Error StdDev Op/s Gen0 Gen1 Allocated
PredicateMultipleIncludes False 242.8 ms 2.39 ms 2.12 ms 4.119 8000.0000 5000.0000 51.69 MB
PredicateMultipleIncludes True 263.4 ms 2.21 ms 2.06 ms 3.797 10000.0000 9000.0000 59.93 MB

Benchmarks indicate that this change represents a sizable chunk of the perf regression introduced in EF9 by the AOT changes, but doesn't fully address it.

Part of #35053