Reflect.Emit Dynamic Type Memory Blowup
- by Firestrand
Using C# 3.5 I am trying to generate dynamic types at runtime using reflection emit. I used the Dynamic Query Library sample from Microsoft to create a class generator. Everything works, my problem is that 100 generated types inflate the memory usage by approximately 25MB. This is a completely unacceptable memory profile as eventually I want to support having several hundred thousand types generated in memory.
Memory profiling shows that the memory is apparently being held by various System.Reflection.Emit types and methods though I can't figure out why. I haven't found others talking about this problem so I am hoping someone in this community either knows what I am doing wrong or if this is expected behavior.
Contrived Example below:
using System;
using System.Collections.Generic;
using System.Text;
using System.Reflection;
using System.Reflection.Emit;
namespace SmallRelfectExample
{
class Program
{
static void Main(string[] args)
{
int typeCount = 100;
int propCount = 100;
Random rand = new Random();
Type dynType = null;
for (int i = 0; i < typeCount; i++)
{
List<DynamicProperty> dpl = new List<DynamicProperty>(propCount);
for (int j = 0; j < propCount; j++)
{
dpl.Add(new DynamicProperty("Key" + rand.Next().ToString(), typeof(String)));
}
SlimClassFactory scf = new SlimClassFactory();
dynType = scf.CreateDynamicClass(dpl.ToArray(), i);
//Optionally do something with the type here
}
Console.WriteLine("SmallRelfectExample: {0} Types generated.", typeCount);
Console.ReadLine();
}
}
public class SlimClassFactory
{
private readonly ModuleBuilder module;
public SlimClassFactory()
{
AssemblyName name = new AssemblyName("DynamicClasses");
AssemblyBuilder assembly = AppDomain.CurrentDomain.DefineDynamicAssembly(name, AssemblyBuilderAccess.Run);
module = assembly.DefineDynamicModule("Module");
}
public Type CreateDynamicClass(DynamicProperty[] properties, int Id)
{
string typeName = "DynamicClass" + Id.ToString();
TypeBuilder tb = module.DefineType(typeName, TypeAttributes.Class |
TypeAttributes.Public, typeof(DynamicClass));
FieldInfo[] fields = GenerateProperties(tb, properties);
GenerateEquals(tb, fields);
GenerateGetHashCode(tb, fields);
Type result = tb.CreateType();
return result;
}
static FieldInfo[] GenerateProperties(TypeBuilder tb, DynamicProperty[] properties)
{
FieldInfo[] fields = new FieldBuilder[properties.Length];
for (int i = 0; i < properties.Length; i++)
{
DynamicProperty dp = properties[i];
FieldBuilder fb = tb.DefineField("_" + dp.Name, dp.Type, FieldAttributes.Private);
PropertyBuilder pb = tb.DefineProperty(dp.Name, PropertyAttributes.HasDefault, dp.Type, null);
MethodBuilder mbGet = tb.DefineMethod("get_" + dp.Name,
MethodAttributes.Public | MethodAttributes.SpecialName | MethodAttributes.HideBySig,
dp.Type, Type.EmptyTypes);
ILGenerator genGet = mbGet.GetILGenerator();
genGet.Emit(OpCodes.Ldarg_0);
genGet.Emit(OpCodes.Ldfld, fb);
genGet.Emit(OpCodes.Ret);
MethodBuilder mbSet = tb.DefineMethod("set_" + dp.Name,
MethodAttributes.Public | MethodAttributes.SpecialName | MethodAttributes.HideBySig,
null, new Type[] { dp.Type });
ILGenerator genSet = mbSet.GetILGenerator();
genSet.Emit(OpCodes.Ldarg_0);
genSet.Emit(OpCodes.Ldarg_1);
genSet.Emit(OpCodes.Stfld, fb);
genSet.Emit(OpCodes.Ret);
pb.SetGetMethod(mbGet);
pb.SetSetMethod(mbSet);
fields[i] = fb;
}
return fields;
}
static void GenerateEquals(TypeBuilder tb, FieldInfo[] fields)
{
MethodBuilder mb = tb.DefineMethod("Equals",
MethodAttributes.Public | MethodAttributes.ReuseSlot |
MethodAttributes.Virtual | MethodAttributes.HideBySig,
typeof(bool), new Type[] { typeof(object) });
ILGenerator gen = mb.GetILGenerator();
LocalBuilder other = gen.DeclareLocal(tb);
Label next = gen.DefineLabel();
gen.Emit(OpCodes.Ldarg_1);
gen.Emit(OpCodes.Isinst, tb);
gen.Emit(OpCodes.Stloc, other);
gen.Emit(OpCodes.Ldloc, other);
gen.Emit(OpCodes.Brtrue_S, next);
gen.Emit(OpCodes.Ldc_I4_0);
gen.Emit(OpCodes.Ret);
gen.MarkLabel(next);
foreach (FieldInfo field in fields)
{
Type ft = field.FieldType;
Type ct = typeof(EqualityComparer<>).MakeGenericType(ft);
next = gen.DefineLabel();
gen.EmitCall(OpCodes.Call, ct.GetMethod("get_Default"), null);
gen.Emit(OpCodes.Ldarg_0);
gen.Emit(OpCodes.Ldfld, field);
gen.Emit(OpCodes.Ldloc, other);
gen.Emit(OpCodes.Ldfld, field);
gen.EmitCall(OpCodes.Callvirt, ct.GetMethod("Equals", new Type[] { ft, ft }), null);
gen.Emit(OpCodes.Brtrue_S, next);
gen.Emit(OpCodes.Ldc_I4_0);
gen.Emit(OpCodes.Ret);
gen.MarkLabel(next);
}
gen.Emit(OpCodes.Ldc_I4_1);
gen.Emit(OpCodes.Ret);
}
static void GenerateGetHashCode(TypeBuilder tb, FieldInfo[] fields)
{
MethodBuilder mb = tb.DefineMethod("GetHashCode",
MethodAttributes.Public | MethodAttributes.ReuseSlot |
MethodAttributes.Virtual | MethodAttributes.HideBySig,
typeof(int), Type.EmptyTypes);
ILGenerator gen = mb.GetILGenerator();
gen.Emit(OpCodes.Ldc_I4_0);
foreach (FieldInfo field in fields)
{
Type ft = field.FieldType;
Type ct = typeof(EqualityComparer<>).MakeGenericType(ft);
gen.EmitCall(OpCodes.Call, ct.GetMethod("get_Default"), null);
gen.Emit(OpCodes.Ldarg_0);
gen.Emit(OpCodes.Ldfld, field);
gen.EmitCall(OpCodes.Callvirt, ct.GetMethod("GetHashCode", new Type[] { ft }), null);
gen.Emit(OpCodes.Xor);
}
gen.Emit(OpCodes.Ret);
}
}
public abstract class DynamicClass
{
public override string ToString()
{
PropertyInfo[] props = GetType().GetProperties(BindingFlags.Instance | BindingFlags.Public);
StringBuilder sb = new StringBuilder();
sb.Append("{");
for (int i = 0; i < props.Length; i++)
{
if (i > 0) sb.Append(", ");
sb.Append(props[i].Name);
sb.Append("=");
sb.Append(props[i].GetValue(this, null));
}
sb.Append("}");
return sb.ToString();
}
}
public class DynamicProperty
{
private readonly string name;
private readonly Type type;
public DynamicProperty(string name, Type type)
{
if (name == null) throw new ArgumentNullException("name");
if (type == null) throw new ArgumentNullException("type");
this.name = name;
this.type = type;
}
public string Name
{
get { return name; }
}
public Type Type
{
get { return type; }
}
}
}
