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Remove some array allocations from RuntimeType.CreateInstanceImpl #67148

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Merged
stephentoub merged 1 commit into from
Mar 25, 2022
Merged

Remove some array allocations from RuntimeType.CreateInstanceImpl #67148

stephentoub merged 1 commit into from
Mar 25, 2022

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@stephentoub stephentoub commented Mar 25, 2022

  • It's commonly used with zero args; we can use Type.EmptyTypes rather than new Type[0]
  • It calls GetConstructors, which internally uses ListBuilder and then resizes if the created array isn't filled, but since we don't need the correctly sized array, we can just use the ListBuilder and avoid the resize
  • It creates a List and then ToArray's it, but if none of the constructors are filtered out, it's better to just use the array we built up directly.
using BenchmarkDotNet.Attributes;
using BenchmarkDotNet.Running;
using System;
using System.Reflection;

[MemoryDiagnoser]
public class Program
{
    static void Main(string[] args) => BenchmarkSwitcher.FromAssembly(typeof(Program).Assembly).Run(args);

    [Benchmark] public void OneZero() => Activator.CreateInstance(typeof(OneCtorZeroArgs), BindingFlags.NonPublic | BindingFlags.Instance, null, Array.Empty<object>(), null);
    [Benchmark] public void OneOne() => Activator.CreateInstance(typeof(OneCtorOneArg), BindingFlags.NonPublic | BindingFlags.Instance, null, new[] { "hello" }, null);
    [Benchmark] public void TwoOne() => Activator.CreateInstance(typeof(TwoCtorOneArg), BindingFlags.NonPublic | BindingFlags.Instance, null, new[] { "hello" }, null);

    internal class OneCtorZeroArgs
    {
        internal OneCtorZeroArgs() { }
    }

    internal class OneCtorOneArg
    {
        internal OneCtorOneArg(string s) { }
    }

    internal class TwoCtorOneArg
    {
        internal TwoCtorOneArg(string s) { }
        internal TwoCtorOneArg(object o) { }
    }
}
Method Toolchain Mean Ratio Allocated
OneZero \main\corerun.exe 181.2 ns 1.00 320 B
OneZero \pr\corerun.exe 148.0 ns 0.82 200 B
OneOne \main\corerun.exe 346.0 ns 1.00 376 B
OneOne \pr\corerun.exe 306.9 ns 0.88 280 B
TwoOne \main\corerun.exe 427.5 ns 1.00 456 B
TwoOne \pr\corerun.exe 414.7 ns 0.97 384 B

@stephentoub
Remove some array allocations from RuntimeType.CreateInstanceImpl
8de4936 
- It's commonly used with zero args; we can use Type.EmptyTypes rather than new Type[0]
- It calls GetConstructors, which internally uses ListBuilder and then resizes if the created array isn't filled, but since we don't need the correctly sized array, we can just use the ListBuilder and avoid the resize
- It creates a List and then ToArray's it, but if none of the constructors are filtered out, it's better to just use the array we built up directly.
@ghost ghost assigned stephentoub Mar 25, 2022
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ghost commented Mar 25, 2022

Tagging subscribers to this area: @dotnet/area-system-reflection
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Issue Details
  • It's commonly used with zero args; we can use Type.EmptyTypes rather than new Type[0]
  • It calls GetConstructors, which internally uses ListBuilder and then resizes if the created array isn't filled, but since we don't need the correctly sized array, we can just use the ListBuilder and avoid the resize
  • It creates a List and then ToArray's it, but if none of the constructors are filtered out, it's better to just use the array we built up directly.
using BenchmarkDotNet.Attributes;
using BenchmarkDotNet.Running;
using System;
using System.Reflection;

[MemoryDiagnoser]
public class Program
{
    static void Main(string[] args) => BenchmarkSwitcher.FromAssembly(typeof(Program).Assembly).Run(args);

    [Benchmark] public void OneZero() => Activator.CreateInstance(typeof(OneCtorZeroArgs), BindingFlags.NonPublic | BindingFlags.Instance, null, Array.Empty<object>(), null);
    [Benchmark] public void OneOne() => Activator.CreateInstance(typeof(OneCtorOneArg), BindingFlags.NonPublic | BindingFlags.Instance, null, new[] { "hello" }, null);
    [Benchmark] public void TwoOne() => Activator.CreateInstance(typeof(TwoCtorOneArg), BindingFlags.NonPublic | BindingFlags.Instance, null, new[] { "hello" }, null);

    internal class OneCtorZeroArgs
    {
        internal OneCtorZeroArgs() { }
    }

    internal class OneCtorOneArg
    {
        internal OneCtorOneArg(string s) { }
    }

    internal class TwoCtorOneArg
    {
        internal TwoCtorOneArg(string s) { }
        internal TwoCtorOneArg(object o) { }
    }
}
Method Toolchain Mean Ratio Allocated
OneZero \main\corerun.exe 181.2 ns 1.00 320 B
OneZero \pr\corerun.exe 148.0 ns 0.82 200 B
OneOne \main\corerun.exe 346.0 ns 1.00 376 B
OneOne \pr\corerun.exe 306.9 ns 0.88 280 B
TwoOne \main\corerun.exe 427.5 ns 1.00 456 B
TwoOne \pr\corerun.exe 414.7 ns 0.97 384 B
Author: stephentoub
Assignees: stephentoub
Labels:

area-System.Reflection
Milestone: -

@stephentoub stephentoub added this to the 7.0.0 milestone Mar 25, 2022
@stephentoub stephentoub merged commit 0c0c7c6 into dotnet:main Mar 25, 2022
@stephentoub stephentoub deleted the createinstancealloc branch March 25, 2022 20:38
radekdoulik pushed a commit to radekdoulik/runtime that referenced this pull request Mar 30, 2022
@stephentoub @radekdoulik
Remove some array allocations from RuntimeType.CreateInstanceImpl (do…
7fc03b3 
…tnet#67148)

- It's commonly used with zero args; we can use Type.EmptyTypes rather than new Type[0]
- It calls GetConstructors, which internally uses ListBuilder and then resizes if the created array isn't filled, but since we don't need the correctly sized array, we can just use the ListBuilder and avoid the resize
- It creates a List and then ToArray's it, but if none of the constructors are filtered out, it's better to just use the array we built up directly.
@ghost ghost locked as resolved and limited conversation to collaborators Apr 25, 2022
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