【发布时间】：2016-02-16 17:07:31
【问题描述】：
对于动态二进制翻译模拟器，我需要生成可收集的 .NET 程序集，其中包含访问静态字段的类。但是，当在可收集程序集中使用静态字段时，与不可收集程序集相比，执行性能要低 2-3 倍。该现象不存在于 不使用静态字段的可收藏程序集。
在下面的代码中，抽象类AbstrTest 的方法MyMethod 由可收集和不可收集的动态程序集实现。使用 CreateTypeConst MyMethod 将 ulong 参数值乘以常数值 2，而使用 CreateTypeField 第二个因子取自
一个构造函数初始化的静态字段MyField。
为了获得真实的结果，MyMethod 结果在 for 循环中累积。
以下是测量结果（.NET CLR 4.5/4.6）：
Testing non-collectible const multiply:
Elapsed: 8721.2867 ms
Testing collectible const multiply:
Elapsed: 8696.8124 ms
Testing non-collectible field multiply:
Elapsed: 10151.6921 ms
Testing collectible field multiply:
Elapsed: 33404.4878 ms
这是我的复制代码：
using System;
using System.Reflection;
using System.Reflection.Emit;
using System.Diagnostics;
public abstract class AbstrTest {
public abstract ulong MyMethod(ulong x);
}
public class DerivedClassBuilder {
private static Type CreateTypeConst(string name, bool collect) {
// Create an assembly.
AssemblyName myAssemblyName = new AssemblyName();
myAssemblyName.Name = name;
AssemblyBuilder myAssembly = AppDomain.CurrentDomain.DefineDynamicAssembly(
myAssemblyName, collect ? AssemblyBuilderAccess.RunAndCollect : AssemblyBuilderAccess.Run);
// Create a dynamic module in Dynamic Assembly.
ModuleBuilder myModuleBuilder = myAssembly.DefineDynamicModule(name);
// Define a public class named "MyClass" in the assembly.
TypeBuilder myTypeBuilder = myModuleBuilder.DefineType("MyClass", TypeAttributes.Public, typeof(AbstrTest));
// Create the MyMethod method.
MethodBuilder myMethodBuilder = myTypeBuilder.DefineMethod("MyMethod",
MethodAttributes.Public | MethodAttributes.ReuseSlot | MethodAttributes.Virtual | MethodAttributes.HideBySig,
typeof(ulong), new Type [] { typeof(ulong) });
ILGenerator methodIL = myMethodBuilder.GetILGenerator();
methodIL.Emit(OpCodes.Ldarg_1);
methodIL.Emit(OpCodes.Ldc_I4_2);
methodIL.Emit(OpCodes.Conv_U8);
methodIL.Emit(OpCodes.Mul);
methodIL.Emit(OpCodes.Ret);
return myTypeBuilder.CreateType();
}
private static Type CreateTypeField(string name, bool collect) {
// Create an assembly.
AssemblyName myAssemblyName = new AssemblyName();
myAssemblyName.Name = name;
AssemblyBuilder myAssembly = AppDomain.CurrentDomain.DefineDynamicAssembly(
myAssemblyName, collect ? AssemblyBuilderAccess.RunAndCollect : AssemblyBuilderAccess.Run);
// Create a dynamic module in Dynamic Assembly.
ModuleBuilder myModuleBuilder = myAssembly.DefineDynamicModule(name);
// Define a public class named "MyClass" in the assembly.
TypeBuilder myTypeBuilder = myModuleBuilder.DefineType("MyClass", TypeAttributes.Public, typeof(AbstrTest));
// Define a private String field named "MyField" in the type.
FieldBuilder myFieldBuilder = myTypeBuilder.DefineField("MyField",
typeof(ulong), FieldAttributes.Private | FieldAttributes.Static);
// Create the constructor.
ConstructorBuilder constructor = myTypeBuilder.DefineConstructor(
MethodAttributes.Public | MethodAttributes.SpecialName | MethodAttributes.RTSpecialName | MethodAttributes.HideBySig,
CallingConventions.Standard, Type.EmptyTypes);
ConstructorInfo superConstructor = typeof(AbstrTest).GetConstructor(
BindingFlags.NonPublic | BindingFlags.Public | BindingFlags.Instance,
null, Type.EmptyTypes, null);
ILGenerator constructorIL = constructor.GetILGenerator();
constructorIL.Emit(OpCodes.Ldarg_0);
constructorIL.Emit(OpCodes.Call, superConstructor);
constructorIL.Emit(OpCodes.Ldc_I4_2);
constructorIL.Emit(OpCodes.Conv_U8);
constructorIL.Emit(OpCodes.Stsfld, myFieldBuilder);
constructorIL.Emit(OpCodes.Ret);
// Create the MyMethod method.
MethodBuilder myMethodBuilder = myTypeBuilder.DefineMethod("MyMethod",
MethodAttributes.Public | MethodAttributes.ReuseSlot | MethodAttributes.Virtual | MethodAttributes.HideBySig,
typeof(ulong), new Type [] { typeof(ulong) });
ILGenerator methodIL = myMethodBuilder.GetILGenerator();
methodIL.Emit(OpCodes.Ldarg_1);
methodIL.Emit(OpCodes.Ldsfld, myFieldBuilder);
methodIL.Emit(OpCodes.Mul);
methodIL.Emit(OpCodes.Ret);
return myTypeBuilder.CreateType();
}
public static void Main() {
ulong accu;
Stopwatch stopwatch;
try {
Console.WriteLine("Testing non-collectible const multiply:");
AbstrTest i0 = (AbstrTest)Activator.CreateInstance(
CreateTypeConst("MyClassModule0", false));
stopwatch = Stopwatch.StartNew();
accu = 0;
for (uint i = 0; i < 0xffffffff; i++)
accu += i0.MyMethod(i);
stopwatch.Stop();
Console.WriteLine("Elapsed: " + stopwatch.Elapsed.TotalMilliseconds + " ms");
Console.WriteLine("Testing collectible const multiply:");
AbstrTest i1 = (AbstrTest)Activator.CreateInstance(
CreateTypeConst("MyClassModule1", true));
stopwatch = Stopwatch.StartNew();
accu = 0;
for (uint i = 0; i < 0xffffffff; i++)
accu += i1.MyMethod(i);
stopwatch.Stop();
Console.WriteLine("Elapsed: " + stopwatch.Elapsed.TotalMilliseconds + " ms");
Console.WriteLine("Testing non-collectible field multiply:");
AbstrTest i2 = (AbstrTest)Activator.CreateInstance(
CreateTypeField("MyClassModule2", false));
stopwatch = Stopwatch.StartNew();
accu = 0;
for (uint i = 0; i < 0xffffffff; i++)
accu += i2.MyMethod(i);
stopwatch.Stop();
Console.WriteLine("Elapsed: " + stopwatch.Elapsed.TotalMilliseconds + " ms");
Console.WriteLine("Testing collectible field multiply:");
AbstrTest i3 = (AbstrTest)Activator.CreateInstance(
CreateTypeField("MyClassModule3", true));
stopwatch = Stopwatch.StartNew();
accu = 0;
for (uint i = 0; i < 0xffffffff; i++)
accu += i3.MyMethod(i);
stopwatch.Stop();
Console.WriteLine("Elapsed: " + stopwatch.Elapsed.TotalMilliseconds + " ms");
}
catch (Exception e) {
Console.WriteLine("Exception Caught " + e.Message);
}
}
}
所以我的问题是：为什么它变慢了？
【问题讨论】：