Tom DuPont .NET: Optimizing Dynamic Method Invokes in .NET

Sunday, August 21, 2016

Optimizing Dynamic Method Invokes in .NET

I recently had a lot of fun helping to optimize some RPC code that was using reflection to dynamically invoke methods in a C# application. Below are a list of implementations that we experimented with, and their performance.

Directly Invoking the Method
Using MethodInfo.Invoke
Using Delegate.DynamicInvoke
Casting to a Func
Casting a Delegate to Dynamic

Spoilers: Here are the results. (The tests for this can be see below.)

Name	First Call (Ticks)	Next Million Calls	Invoke Comparison
Invoke	1	39795	-
MethodInfo.Invoke	12	967523	x24
Delegate.DynamicInvoke	32	1580086	x39
Func Invoke	731	41331	x1
Dynamic Cast	1126896	85495	x2

Conclusion: Invoking a method or delegate directly is always fastest, but when you need to execute code dynamically, then (after the first invoke) the dynamic invoke of a delegate is significantly faster than using reflection.

Let's take a look at the test code...

Unit Tests

public class InvokePerformance

 public const int Iterations = 1000000;

 public static readonly object[] Args = {1, true};

 public static readonly TestClass Obj = new TestClass();

 public static readonly Type Type = typeof(TestClass);

 public static readonly MethodInfo Method = Type.GetMethod("TestMethod");

 private readonly ITestOutputHelper _output;

 public InvokePerformance(ITestOutputHelper output)

 _output = output;

 [Fact]

 public void Invoke()

 var arg0 = (int) Args[0];

 var arg1 = (bool) Args[1];

 var sw0 = Stopwatch.StartNew();

 Method.Invoke(Obj, Args);

 sw0.Stop();

 var sw1 = Stopwatch.StartNew();

 for (var i = 0; i < Iterations; i++)

 Obj.TestMethod(arg0, arg1);

 sw1.Stop();

 _output.WriteLine(sw0.ElapsedTicks.ToString());

 _output.WriteLine(sw1.ElapsedTicks.ToString());

 [Fact]

 public void MethodInfoInvoke()

 var sw0 = Stopwatch.StartNew();

 Method.Invoke(Obj, Args);

 sw0.Stop();

 var sw1 = Stopwatch.StartNew();

 for (var i = 0; i < Iterations; i++)

 Method.Invoke(Obj, Args);

 sw1.Stop();

 _output.WriteLine(sw0.ElapsedTicks.ToString());

 _output.WriteLine(sw1.ElapsedTicks.ToString());

 [Fact]

 public void DelegateDynamicInvoke()

 var delType = Expression.GetDelegateType(typeof(int), typeof(bool), typeof(int));

 var del = Delegate.CreateDelegate(delType, Obj, Method);

 var sw0 = Stopwatch.StartNew();

 del.DynamicInvoke(Args);

 sw0.Stop();

 var sw1 = Stopwatch.StartNew();

 for (var i = 0; i < Iterations; i++)

 del.DynamicInvoke(Args);

 sw1.Stop();

 _output.WriteLine(sw0.ElapsedTicks.ToString());

 _output.WriteLine(sw1.ElapsedTicks.ToString());

 [Fact]

 public void FuncInvoke()

 var delType = Expression.GetDelegateType(typeof(int), typeof(bool), typeof(int));

 var del = (Func<int, bool, int>) Delegate.CreateDelegate(delType, Obj, Method);

 var arg0 = (int) Args[0];

 var arg1 = (bool) Args[1];

 var sw0 = Stopwatch.StartNew();

 del(arg0, arg1);

 sw0.Stop();

 var sw1 = Stopwatch.StartNew();

 for (var i = 0; i < Iterations; i++)

 del(arg0, arg1);

 sw1.Stop();

 _output.WriteLine(sw0.ElapsedTicks.ToString());

 _output.WriteLine(sw1.ElapsedTicks.ToString());

 [Fact]

 public void DynamicCast()

 var delType = Expression.GetDelegateType(typeof(int), typeof(bool), typeof(int));

 dynamic del = Delegate.CreateDelegate(delType, Obj, Method);

 dynamic arg0 = Args[0];

 dynamic arg1 = Args[1];

 var sw0 = Stopwatch.StartNew();

 del(arg0, arg1);

 sw0.Stop();

 var sw1 = Stopwatch.StartNew();

 for (var i = 0; i < Iterations; i++)

 del(arg0, arg1);

 sw1.Stop();

 _output.WriteLine(sw0.ElapsedTicks.ToString());

 _output.WriteLine(sw1.ElapsedTicks.ToString());

 public class TestClass

 public int TestMethod(int i, bool b)

 return i + (b ? 1 : 2);

Tom DuPont .NET

Sunday, August 21, 2016

Optimizing Dynamic Method Invokes in .NET

Unit Tests

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