为什么在 Expression.Call 上构建的编译 lambda 比应该做同样事情的委托稍慢？
Why compiled lambda build over Expression.Call is slightly slower than delegate that should do the same?
为什么在 Expression.Call 上编译的 lambda 构建比应该执行相同操作的委托稍慢？以及如何避免呢？
解释 BenchmarkDotNet 结果。
我们正在比较 CallBuildedReal 与 CallLambda；其他两个 CallBuilded 和 CallLambdaConst 是 "subforms" of CallLambda 并且显示相同的数字。但是与 CallBuildedReal 的区别是显着的。
//[Config(typeof(Config))]
[RankColumn, MinColumn, MaxColumn, StdDevColumn, MedianColumn]
[ClrJob , CoreJob]
[HtmlExporter, MarkdownExporter]
[MemoryDiagnoser /*, InliningDiagnoser*/]
public class BenchmarkCallSimple
{
static Func<StringBuilder, int, int, bool> callLambda;
static Func<StringBuilder, int, int, bool> callLambdaConst;
static Func<StringBuilder, int, int, bool> callBuilded;
static Func<StringBuilder, int, int, bool> callBuildedReal;
private static bool Append<T>(StringBuilder sb, T i1, T i2, Func<T, T, T> operation)
{
sb.Append(operation(i1, i2));
return true;
}
private static Func<StringBuilder, T, T, bool> BuildCallMethod<T>(Func<T, T, T> operation)
{
return (sb, i1, i2)=> { sb.Append(operation(i1, i2)); return true; };
}
private static int AddMethod(int a, int b)
{
return a + b;
}
static BenchmarkCallSimple()
{
var x = Expression.Parameter(typeof(int));
var y = Expression.Parameter(typeof(int));
var additionExpr = Expression.Add(x, y);
callLambdaConst = BuildCallMethod<int>(AddMethod);
callLambda = BuildCallMethod<int>((a, b) => a + b);
var operationDelegate = Expression.Lambda<Func<int, int, int>>(additionExpr, x, y).Compile();
callBuilded = BuildCallMethod(operationDelegate);
var operationExpressionConst = Expression.Constant(operationDelegate, operationDelegate.GetType());
var sb1 = Expression.Parameter(typeof(StringBuilder), "sb");
var i1 = Expression.Parameter(typeof(int), "i1");
var i2 = Expression.Parameter(typeof(int), "i2");
var appendMethodInfo = typeof(BenchmarkCallSimple).GetTypeInfo().GetDeclaredMethod(nameof(BenchmarkCallSimple.Append));
var appendMethodInfoGeneric = appendMethodInfo.MakeGenericMethod(typeof(int));
var appendCallExpression = Expression.Call(appendMethodInfoGeneric,
new Expression[] { sb1, i1, i2, operationExpressionConst }
);
var appendLambda = Expression.Lambda(appendCallExpression, new[] { sb1, i1, i2 });
callBuildedReal = (Func<StringBuilder, int, int, bool>)(appendLambda.Compile());
}
[Benchmark]
public string CallBuildedReal()
{
StringBuilder sb = new StringBuilder();
var b = callBuildedReal(sb, 1, 2);
return sb.ToString();
}
[Benchmark]
public string CallBuilded()
{
StringBuilder sb = new StringBuilder();
var b = callBuilded(sb, 1, 2);
return sb.ToString();
}
[Benchmark]
public string CallLambda()
{
StringBuilder sb = new StringBuilder();
var b = callLambda(sb, 1, 2);
return sb.ToString();
}
[Benchmark]
public string CallLambdaConst()
{
StringBuilder sb = new StringBuilder();
var b = callLambdaConst(sb, 1, 2);
return sb.ToString();
}
}
结果：
BenchmarkDotNet=v0.10.5, OS=Windows 10.0.14393
Processor=Intel Core i5-2500K CPU 3.30GHz (Sandy Bridge), ProcessorCount=4
Frequency=3233539 Hz, Resolution=309.2587 ns, Timer=TSC
[Host] : Clr 4.0.30319.42000, 64bit RyuJIT-v4.6.1648.0
Clr : Clr 4.0.30319.42000, 64bit RyuJIT-v4.6.1648.0
Core : .NET Core 4.6.25009.03, 64bit RyuJIT
Method | Job | Runtime | Mean | Error | StdDev | Min | Max | Median | Rank | Gen 0 | Allocated |
---------------- |----- |-------- |---------:|---------:|---------:|---------:|---------:|---------:|-----:|-------:|----------:|
CallBuildedReal | Clr | Clr | 137.8 ns | 2.903 ns | 4.255 ns | 133.6 ns | 149.6 ns | 135.6 ns | 7 | 0.0580 | 192 B |
CallBuilded | Clr | Clr | 122.7 ns | 2.068 ns | 1.934 ns | 118.5 ns | 126.2 ns | 122.6 ns | 6 | 0.0576 | 192 B |
CallLambda | Clr | Clr | 119.8 ns | 1.342 ns | 1.255 ns | 117.9 ns | 121.7 ns | 119.6 ns | 5 | 0.0576 | 192 B |
CallLambdaConst | Clr | Clr | 121.7 ns | 1.347 ns | 1.194 ns | 120.1 ns | 124.5 ns | 121.6 ns | 6 | 0.0571 | 192 B |
CallBuildedReal | Core | Core | 114.8 ns | 2.263 ns | 2.117 ns | 112.7 ns | 118.8 ns | 113.7 ns | 3 | 0.0594 | 191 B |
CallBuilded | Core | Core | 109.0 ns | 1.701 ns | 1.591 ns | 106.5 ns | 112.2 ns | 108.8 ns | 2 | 0.0599 | 191 B |
CallLambda | Core | Core | 107.0 ns | 1.181 ns | 1.105 ns | 105.7 ns | 109.4 ns | 106.8 ns | 1 | 0.0593 | 191 B |
CallLambdaConst | Core | Core | 117.3 ns | 2.706 ns | 3.704 ns | 113.4 ns | 127.8 ns | 116.0 ns | 4 | 0.0592 | 191 B |
基准代码：
注意 1：有类似的 SO 线程“Performance of expression trees”，其中构建表达式在基准测试中显示最佳结果。
注2：等我拿到编译表达式的IL代码我应该就快回答了，所以我正在努力学习如何获取编译表达式的IL代码（linqpad？，ilasm integrated to VS？，动态装配？），但如果你知道可以从 VS 中完成的简单插件 - 它会对我有很大帮助。
注3：这行不通
var assemblyBuilder = System.AppDomain.CurrentDomain.DefineDynamicAssembly(new AssemblyName("testLambda"),System.Reflection.Emit.AssemblyBuilderAccess.Save);
var modelBuilder = assemblyBuilder.DefineDynamicModule("testLambda_module", "testLambda.dll");
var typeBuilder = modelBuilder.DefineType("testLambda_type");
var method = typeBuilder.DefineMethod("testLambda_method", MethodAttributes.Public | MethodAttributes.Static, typeof(bool),
new[] { typeof(StringBuilder), typeof(int), typeof(int), typeof(bool) });
appendLambda.CompileToMethod(method);
typeBuilder.CreateType();
assemblyBuilder.Save("testLambda.dll");
因为System.TypeInitializationException: "InvalidOperationException: CompileToMethod cannot compile constant 'System.Func3[System.Int32,System.Int32,System.Int32]' because it is a non-trivial value, such as a live object. Instead, create an expression tree that can construct this value."
That meansappendLambda` contains a parameter type of is Func这不是原始类型，CompileToMethod 只能使用原始类型。
由于 reasons:
编译的表达式可能较慢
TL;DR;
The question is, why is the compiled delegate way slower than a manually-written delegate? Expression.Compile creates a DynamicMethod and associates it with an anonymous assembly to run it in a sand-boxed environment. This makes it safe for a dynamic method to be emitted and executed by partially trusted code but adds some run-time overhead.
有像 FastExpressionCompiler 这样的工具可以帮助缓解这个问题（免责声明：我是作者）
更新：查看已编译委托的IL
可以将已编译的委托 IL 作为字节数组获取：
var hello = "Hello";
Expression<Func<string>> getGreetingExpr = () => hello + " me";
var getGreeting = getGreetingExpr.Compile();
var methodBody = getGreeting.Method.GetMethodBody();
var ilBytes = methodBody.GetILAsByteArray();
您需要一种方法来 parse/read 数组并将其转换为 IL 指令和参数。
可惜，但我没有找到允许我这样做的工具或强大的 NuGet 包:-(
这是相关的SO question。
最近的工具可能是 this。
为什么在 Expression.Call 上编译的 lambda 构建比应该执行相同操作的委托稍慢？以及如何避免呢？
解释 BenchmarkDotNet 结果。
我们正在比较 CallBuildedReal 与 CallLambda；其他两个 CallBuilded 和 CallLambdaConst 是 "subforms" of CallLambda 并且显示相同的数字。但是与 CallBuildedReal 的区别是显着的。
//[Config(typeof(Config))]
[RankColumn, MinColumn, MaxColumn, StdDevColumn, MedianColumn]
[ClrJob , CoreJob]
[HtmlExporter, MarkdownExporter]
[MemoryDiagnoser /*, InliningDiagnoser*/]
public class BenchmarkCallSimple
{
static Func<StringBuilder, int, int, bool> callLambda;
static Func<StringBuilder, int, int, bool> callLambdaConst;
static Func<StringBuilder, int, int, bool> callBuilded;
static Func<StringBuilder, int, int, bool> callBuildedReal;
private static bool Append<T>(StringBuilder sb, T i1, T i2, Func<T, T, T> operation)
{
sb.Append(operation(i1, i2));
return true;
}
private static Func<StringBuilder, T, T, bool> BuildCallMethod<T>(Func<T, T, T> operation)
{
return (sb, i1, i2)=> { sb.Append(operation(i1, i2)); return true; };
}
private static int AddMethod(int a, int b)
{
return a + b;
}
static BenchmarkCallSimple()
{
var x = Expression.Parameter(typeof(int));
var y = Expression.Parameter(typeof(int));
var additionExpr = Expression.Add(x, y);
callLambdaConst = BuildCallMethod<int>(AddMethod);
callLambda = BuildCallMethod<int>((a, b) => a + b);
var operationDelegate = Expression.Lambda<Func<int, int, int>>(additionExpr, x, y).Compile();
callBuilded = BuildCallMethod(operationDelegate);
var operationExpressionConst = Expression.Constant(operationDelegate, operationDelegate.GetType());
var sb1 = Expression.Parameter(typeof(StringBuilder), "sb");
var i1 = Expression.Parameter(typeof(int), "i1");
var i2 = Expression.Parameter(typeof(int), "i2");
var appendMethodInfo = typeof(BenchmarkCallSimple).GetTypeInfo().GetDeclaredMethod(nameof(BenchmarkCallSimple.Append));
var appendMethodInfoGeneric = appendMethodInfo.MakeGenericMethod(typeof(int));
var appendCallExpression = Expression.Call(appendMethodInfoGeneric,
new Expression[] { sb1, i1, i2, operationExpressionConst }
);
var appendLambda = Expression.Lambda(appendCallExpression, new[] { sb1, i1, i2 });
callBuildedReal = (Func<StringBuilder, int, int, bool>)(appendLambda.Compile());
}
[Benchmark]
public string CallBuildedReal()
{
StringBuilder sb = new StringBuilder();
var b = callBuildedReal(sb, 1, 2);
return sb.ToString();
}
[Benchmark]
public string CallBuilded()
{
StringBuilder sb = new StringBuilder();
var b = callBuilded(sb, 1, 2);
return sb.ToString();
}
[Benchmark]
public string CallLambda()
{
StringBuilder sb = new StringBuilder();
var b = callLambda(sb, 1, 2);
return sb.ToString();
}
[Benchmark]
public string CallLambdaConst()
{
StringBuilder sb = new StringBuilder();
var b = callLambdaConst(sb, 1, 2);
return sb.ToString();
}
}
结果：
BenchmarkDotNet=v0.10.5, OS=Windows 10.0.14393
Processor=Intel Core i5-2500K CPU 3.30GHz (Sandy Bridge), ProcessorCount=4
Frequency=3233539 Hz, Resolution=309.2587 ns, Timer=TSC
[Host] : Clr 4.0.30319.42000, 64bit RyuJIT-v4.6.1648.0
Clr : Clr 4.0.30319.42000, 64bit RyuJIT-v4.6.1648.0
Core : .NET Core 4.6.25009.03, 64bit RyuJIT
Method | Job | Runtime | Mean | Error | StdDev | Min | Max | Median | Rank | Gen 0 | Allocated |
---------------- |----- |-------- |---------:|---------:|---------:|---------:|---------:|---------:|-----:|-------:|----------:|
CallBuildedReal | Clr | Clr | 137.8 ns | 2.903 ns | 4.255 ns | 133.6 ns | 149.6 ns | 135.6 ns | 7 | 0.0580 | 192 B |
CallBuilded | Clr | Clr | 122.7 ns | 2.068 ns | 1.934 ns | 118.5 ns | 126.2 ns | 122.6 ns | 6 | 0.0576 | 192 B |
CallLambda | Clr | Clr | 119.8 ns | 1.342 ns | 1.255 ns | 117.9 ns | 121.7 ns | 119.6 ns | 5 | 0.0576 | 192 B |
CallLambdaConst | Clr | Clr | 121.7 ns | 1.347 ns | 1.194 ns | 120.1 ns | 124.5 ns | 121.6 ns | 6 | 0.0571 | 192 B |
CallBuildedReal | Core | Core | 114.8 ns | 2.263 ns | 2.117 ns | 112.7 ns | 118.8 ns | 113.7 ns | 3 | 0.0594 | 191 B |
CallBuilded | Core | Core | 109.0 ns | 1.701 ns | 1.591 ns | 106.5 ns | 112.2 ns | 108.8 ns | 2 | 0.0599 | 191 B |
CallLambda | Core | Core | 107.0 ns | 1.181 ns | 1.105 ns | 105.7 ns | 109.4 ns | 106.8 ns | 1 | 0.0593 | 191 B |
CallLambdaConst | Core | Core | 117.3 ns | 2.706 ns | 3.704 ns | 113.4 ns | 127.8 ns | 116.0 ns | 4 | 0.0592 | 191 B |
基准代码：
注意 1：有类似的 SO 线程“Performance of expression trees”，其中构建表达式在基准测试中显示最佳结果。
注2：等我拿到编译表达式的IL代码我应该就快回答了，所以我正在努力学习如何获取编译表达式的IL代码（linqpad？，ilasm integrated to VS？，动态装配？），但如果你知道可以从 VS 中完成的简单插件 - 它会对我有很大帮助。
注3：这行不通
var assemblyBuilder = System.AppDomain.CurrentDomain.DefineDynamicAssembly(new AssemblyName("testLambda"),System.Reflection.Emit.AssemblyBuilderAccess.Save);
var modelBuilder = assemblyBuilder.DefineDynamicModule("testLambda_module", "testLambda.dll");
var typeBuilder = modelBuilder.DefineType("testLambda_type");
var method = typeBuilder.DefineMethod("testLambda_method", MethodAttributes.Public | MethodAttributes.Static, typeof(bool),
new[] { typeof(StringBuilder), typeof(int), typeof(int), typeof(bool) });
appendLambda.CompileToMethod(method);
typeBuilder.CreateType();
assemblyBuilder.Save("testLambda.dll");
因为System.TypeInitializationException: "InvalidOperationException: CompileToMethod cannot compile constant 'System.Func3[System.Int32,System.Int32,System.Int32]' because it is a non-trivial value, such as a live object. Instead, create an expression tree that can construct this value."
That meansappendLambda` contains a parameter type of is Func这不是原始类型，CompileToMethod 只能使用原始类型。
由于 reasons:
编译的表达式可能较慢TL;DR;
The question is, why is the compiled delegate way slower than a manually-written delegate? Expression.Compile creates a DynamicMethod and associates it with an anonymous assembly to run it in a sand-boxed environment. This makes it safe for a dynamic method to be emitted and executed by partially trusted code but adds some run-time overhead.
有像 FastExpressionCompiler 这样的工具可以帮助缓解这个问题（免责声明：我是作者）
更新：查看已编译委托的IL
可以将已编译的委托 IL 作为字节数组获取：
var hello = "Hello"; Expression<Func<string>> getGreetingExpr = () => hello + " me"; var getGreeting = getGreetingExpr.Compile(); var methodBody = getGreeting.Method.GetMethodBody(); var ilBytes = methodBody.GetILAsByteArray();您需要一种方法来 parse/read 数组并将其转换为 IL 指令和参数。
可惜，但我没有找到允许我这样做的工具或强大的 NuGet 包:-(
这是相关的SO question。
最近的工具可能是 this。