Efcore: Regression in single context creation perf

[ajcvickers]

[smitpatel]

Suspected commit according to meeting https://github.com/dotnet/efcore/pull/19517/files

Does initializing context also initializes DbSets even if not used?

[AndriySvyryd]

@smitpatel That's pretty much the only thing that happens before a context is used https://github.com/dotnet/efcore/blob/master/src/EFCore/DbContext.cs#L112

[AndriySvyryd]

And if we can confirm that https://github.com/dotnet/efcore/pull/19517 caused it we don't have or really can fix it

[roji]

Should be really easy to simply run the benchmark on the cmdline on both commits to check (let me know if you run into trouble).

[smitpatel]

Seems like @roji is volunteering to verify the commit for regression.

[roji]

That was not quite the semantic content of my message... however:

Before change (f98509f442d4b034b42d8130fff48ee0c73d20f0)

BenchmarkDotNet=v0.11.3, OS=ubuntu 19.10
Intel Xeon W-2133 CPU 3.60GHz, 1 CPU, 12 logical and 6 physical cores
.NET Core SDK=3.1.100
  [Host] : .NET Core 3.1.1 (CoreCLR 4.700.19.60701, CoreFX 4.700.19.60801), 64bit RyuJIT

Toolchain=InProcessToolchain  

| Method | Mean | Error | StdDev | Gen 0/1k Op | Gen 1/1k Op | Gen 2/1k Op | Allocated Memory/Op |
|------------------------------ |---------:|---------:|---------:|------------:|------------:|------------:|--------------------:|
| CreateAndDisposeUnusedContext | 142.0 ms | 1.142 ms | 1.068 ms | 34250.0000 | - | - | 141.75 MB |

After change (dd843a2db241572395fd1c26ba7fc4e7e1e6ba72)

BenchmarkDotNet=v0.11.3, OS=ubuntu 19.10
Intel Xeon W-2133 CPU 3.60GHz, 1 CPU, 12 logical and 6 physical cores
.NET Core SDK=3.1.100
  [Host] : .NET Core 3.1.1 (CoreCLR 4.700.19.60701, CoreFX 4.700.19.60801), 64bit RyuJIT

Toolchain=InProcessToolchain  

| Method | Mean | Error | StdDev | Median | Gen 0/1k Op | Gen 1/1k Op | Gen 2/1k Op | Allocated Memory/Op |
|------------------------------ |---------:|---------:|---------:|---------:|------------:|------------:|------------:|--------------------:|
| CreateAndDisposeUnusedContext | 193.7 ms | 3.860 ms | 9.825 ms | 188.1 ms | 38000.0000 | - | - | 158.54 MB |

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For reference, running is super simple has no hard dependency on @roji:

• cd benchmark/EFCore.Sqlite.Benchmarks (invert slashes if on exotic operating systems)
• dotnet run -c Release -f netcoreapp3.1 -- --filter "*CreateAndDisposeUnusedContext*" --inProcess

[smitpatel]

That was not quite the semantic content of my message... however:

Oops! My mistake! 😉

[ajcvickers]

I have ideas.