10

我有一个方法,它使用7,753+对象循环并获取每个对象的每个属性的值。每个对象都有14属性。

private void InitializeData(IList objects, PropertyInfo[] props, List<DPV> dataPs, List<Dictionary<string, object>> tod)
{
    foreach (var item in objects)
    {
        var kvp = new Dictionary<string, object>();
        foreach (var p in props)
        {
            var dataPs = dataPs.FirstOrDefault(x => x.Name == p.Name);
            object returnData;
            if (dataPoint != null)
            {
                int maxLength = (dataP.MaxLength == null) ? 0 : (int) dataP.MaxLength;
                returnData = p.GetValue(item, null);
                if (!string.IsNullOrEmpty(dataP.FormatString) && !string.IsNullOrEmpty(returnData.ToString()))
                {
                    returnData = FormatDataForDisplay(returnData, dataP, maxLength, "", 8);
                }
            }
            else
            {
                returnData = p.GetValue(item, null);
            }
            kvp.Add(p.Name, returnData);
        }
        tod.Add(kvp);
    }
}

我相信GetValue是这种方法花费了大部分时间,该方法需要900ms运行,但GetValue称为800,000+时间需要750ms (total, not per-call)

public List<Dictionary<string, object>> GetColumnOptions<T>(List<T> list)
    {

        var tod= new List<Dictionary<string, object>>();



        var objects = (IList)list[0];
        Type objType = objects[0].GetType();

        var props = objType.GetProperties(BindingFlags.DeclaredOnly |
                                                         BindingFlags.Public |
                                                         BindingFlags.Instance);


        var dPs= GetDPs();



        //Initialize aaData
        //I don't believe this is correct
        InitializeData2<T>(new List<T> { (T) objects}, props, dPs, tod);

        return tod;
    }
4

4 回答 4

19

对于您的值类,您可以创建直接 setter 和 getter lambda。
性能几乎与直接访问属性一样快。

从 PropertyInfo 获取 Setter

var propertyInfo = typeof(MyType).GetProperty("MyPropertValue");
var propertySetter = FastInvoke.BuildUntypedSetter<T>(propertyInfo));
var fieldInfo = typeof(MyType).GetField("MyFieldValue");
var fieldSetter = FastInvoke.BuildUntypedSetter<T>(fieldInfo));

循环使用

var myTarget = new MyType();
setter(myTarget, aNewValue)

检索快速 Setter 和 Getter 的助手

public static class FastInvoke {

    public static Func<T, object> BuildUntypedGetter<T>(MemberInfo memberInfo)
    {
        var targetType = memberInfo.DeclaringType;
        var exInstance = Expression.Parameter(targetType, "t");

        var exMemberAccess = Expression.MakeMemberAccess(exInstance, memberInfo);       // t.PropertyName
        var exConvertToObject = Expression.Convert(exMemberAccess, typeof(object));     // Convert(t.PropertyName, typeof(object))
        var lambda = Expression.Lambda<Func<T, object>>(exConvertToObject, exInstance);

        var action = lambda.Compile();
        return action;
    }

    public static Action<T, object> BuildUntypedSetter<T>(MemberInfo memberInfo)
    {
        var targetType = memberInfo.DeclaringType;
        var exInstance = Expression.Parameter(targetType, "t");

        var exMemberAccess = Expression.MakeMemberAccess(exInstance, memberInfo);

        // t.PropertValue(Convert(p))
        var exValue = Expression.Parameter(typeof(object), "p");
        var exConvertedValue = Expression.Convert(exValue, GetUnderlyingType(memberInfo));
        var exBody = Expression.Assign(exMemberAccess, exConvertedValue);

        var lambda = Expression.Lambda<Action<T, object>>(exBody, exInstance, exValue);
        var action = lambda.Compile();
        return action;
    }

    private static Type GetUnderlyingType(this MemberInfo member)
    {
        switch (member.MemberType)
        {
            case MemberTypes.Event:
                return ((EventInfo)member).EventHandlerType;
            case MemberTypes.Field:
                return ((FieldInfo)member).FieldType;
            case MemberTypes.Method:
                return ((MethodInfo)member).ReturnType;
            case MemberTypes.Property:
                return ((PropertyInfo)member).PropertyType;
            default:
                throw new ArgumentException
                (
                 "Input MemberInfo must be if type EventInfo, FieldInfo, MethodInfo, or PropertyInfo"
                );
        }
    }
}

============= 添加性能分析 ===================

5 个 Mio 对象,20 个属性

  • 3.4s直接属性访问
  • 130.0s通过 PropertyInfo.SetValue
  • 4.0s via TypedSetter(代码见文章)
  • 9.8 秒通过UnTypedSetter(上面的代码)

诀窍是为每个类生成一次属性设置器和-getter,然后重用它们。

// Create an fill objects fast from DataReader
// http://flurfunk.sdx-ag.de/2012/05/c-performance-bei-der-befullungmapping.html 
static List<T> CreateObjectFromReader<T>(IDataReader reader)
    where T : new()
{
  // Prepare
  List<string> fieldNames = GetFieldNames(reader);
  List<Action<T, object>> setterList = new List<Action<T, object>>();
 
  // Create Property-Setter and store it in an array 
  foreach (var field in fieldNames)
  {
    var propertyInfo = typeof(T).GetProperty(field);
    setterList.Add(FastInvoke.BuildUntypedSetter<T>(propertyInfo));
  }
  Action<T, object>[] setterArray = setterList.ToArray();
 
  // generate and fill objects
  while (reader.Read())
  {
    T xclass = new T();
    int fieldNumber = 0;
 
    for (int i = 0; i< setterArray.Length; i++) 
    {
        // call setter
        setterArray[i](xclass, reader.GetValue(i));
        fieldNumber++;
    } 
    result.Add(xclass);
  }
}

我的原始文章(德语文本和旧代码)是https://web.archive.org/web/20141020092917/http://flurfunk.sdx-ag.de/2012/05/c-performance-bei-der-befullungmapping .html

于 2013-07-16T06:03:30.543 回答
3

如果问题确实出在PropertyInfo.GetValue方法调用中,您可以使用构建属性获取器缓存的方法(例如通过编译的表达式)。这是一个示例,它证明了这种方法在 8000 个具有 14 个属性的对象(带有热缓存)上比原始方法快 30-40%:

static void Main(string[] args) {
    IList objects = new List<Obj>();
    for(int i = 0; i < 8000; i++)
        objects.Add(new Obj());
    var properties = typeof(Obj).GetProperties();


    var sw1 = System.Diagnostics.Stopwatch.StartNew();
    InitializeData1(objects, properties, new List<Dictionary<string, object>>());
    sw1.Stop();
    Console.WriteLine("Reflection PropertyInfo.GetValue: " + sw1.ElapsedTicks.ToString());

    // cold cache testing
    var sw2_coldCache = System.Diagnostics.Stopwatch.StartNew();
    InitializeData2<Obj>(objects, properties, new List<Dictionary<string, object>>(), new Dictionary<string, Func<Obj, object>>());
    sw2_coldCache.Stop();
    Console.WriteLine("Cached Getters (Cold cache): " + sw2_coldCache.ElapsedTicks.ToString());

    // cache initialization
    InitializeData2<Obj>(new List<Obj> { new Obj() }, properties, new List<Dictionary<string, object>>(), gettersCache);
    // hot cache testing
    var sw2_hotCache = System.Diagnostics.Stopwatch.StartNew();
    InitializeData2<Obj>(objects, properties, new List<Dictionary<string, object>>(), gettersCache);
    sw2_hotCache.Stop();
    Console.WriteLine("Cached Getters (Hot cache): " + sw2_hotCache.ElapsedTicks.ToString());

    var sw3 = System.Diagnostics.Stopwatch.StartNew();
    InitializeData3(objects, properties, new List<Dictionary<string, object>>());
    sw3.Stop();
    Console.WriteLine("returnProps special method: " + sw3.ElapsedTicks.ToString());

    var sw4 = System.Diagnostics.Stopwatch.StartNew();
    InitializeData2_NonGeneric(objects, properties, new List<Dictionary<string, object>>());
    sw4.Stop();
    Console.WriteLine("Cached Getters (runtime types resolving): " + sw4.ElapsedTicks.ToString());
}

这是原始实现(出于测试目的而减少):

static void InitializeData1(IList objects, PropertyInfo[] props, List<Dictionary<string, object>> tod) {
    foreach(var item in objects) {
        var kvp = new Dictionary<string, object>();
        foreach(var p in props) {
            kvp.Add(p.Name, p.GetValue(item, null));
        }
        tod.Add(kvp);
    }
}

这是优化的实现:

static IDictionary<string, Func<Obj, object>> gettersCache = new Dictionary<string, Func<Obj, object>>();
static void InitializeData2<T>(IList objects, PropertyInfo[] props, List<Dictionary<string, object>> tod, IDictionary<string, Func<T, object>> getters) {
    Func<T, object> getter;
    foreach(T item in objects) {
        var kvp = new Dictionary<string, object>();
        foreach(var p in props) {
            if(!getters.TryGetValue(p.Name, out getter)) {
                getter = GetValueGetter<T>(p);
                getters.Add(p.Name, getter);
            }
            kvp.Add(p.Name, getter(item));
        }
        tod.Add(kvp);
    }
}

static Func<T, object> GetValueGetter<T>(PropertyInfo propertyInfo) {
    var instance = System.Linq.Expressions.Expression.Parameter(propertyInfo.DeclaringType, "i");
    var property = System.Linq.Expressions.Expression.Property(instance, propertyInfo);
    var convert = System.Linq.Expressions.Expression.TypeAs(property, typeof(object));
    return (Func<T, object>)System.Linq.Expressions.Expression.Lambda(convert, instance).Compile();
}

测试类:

class Obj {
    public int p00 { set; get; }
    public string p01 { set; get; }
    public float p02 { set; get; }
    public double p03 { set; get; }
    public char p04 { set; get; }
    public byte p05 { set; get; }
    public long p06 { set; get; }
    public int p07 { set; get; }
    public string p08 { set; get; }
    public float p09 { set; get; }
    public double p10 { set; get; }
    public char p11 { set; get; }
    public byte p12 { set; get; }
    public long p13 { set; get; }
}

更新:将varocarbas的解决方案添加到测试中

static void InitializeData3(IList objects, PropertyInfo[] props, List<Dictionary<string, object>> tod) {
    foreach(Obj item in objects) {
        var kvp = new Dictionary<string, object>();
        foreach(var p in props) {
            kvp.Add(p.Name, returnProps(p.Name, item));
        }
        tod.Add(kvp);
    }
}
static object returnProps(string propName, Obj curObject) {
    if(propName == "p00") {
        return curObject.p00;
    }
    else if(propName == "p01") {
        return curObject.p01;
    }
    else if(propName == "p02") {
        return curObject.p02;
    }
    else if(propName == "p03") {
        return curObject.p03;
    }
    else if(propName == "p04") {
        return curObject.p04;
    }
    else if(propName == "p05") {
        return curObject.p05;
    }
    else if(propName == "p06") {
        return curObject.p06;
    }
    else if(propName == "p07") {
        return curObject.p07;
    }
    else if(propName == "p08") {
        return curObject.p08;
    }
    else if(propName == "p09") {
        return curObject.p09;
    }
    else if(propName == "p10") {
        return curObject.p10;
    }
    else if(propName == "p11") {
        return curObject.p11;
    }
    else if(propName == "p12") {
        return curObject.p12;
    }
    else if(propName == "p13") {
        return curObject.p13;
    }
    return new object();
}

控制台结果:(发布,x64)(Core i5 M560 @2.67 GHz,8GB RAM,Win7x64)

Reflection PropertyInfo.GetValue: 161288
Cached Getters (Cold cache): 153808
Cached Getters (Hot cache): 110837
returnProps special method: 128905

因此,缓存方法是最好的。

更新
2示例中演示的方法旨在在编译时已知objects元素类型时使用(通用方式):

InitializeData2<Obj>(...)

如果您在编译时使用类型未知的对象列表,则可以使用以下InitializeData2<>方法在运行时调用泛型方法:

InitializeData2_NonGeneric(objects, properties, new List<Dictionary<string, object>>());
//...
static void InitializeData2_NonGeneric(IList objects, PropertyInfo[] props, List<Dictionary<string, object>> tod) {
    Type elementType = objects[0].GetType();
    var genericMethodInfo = typeof(Program).GetMethod("InitializeData2", BindingFlags.Static | BindingFlags.NonPublic);
    var genericMethod = genericMethodInfo.MakeGenericMethod(new Type[] { elementType });

    var genericGetterType = typeof(Func<,>).MakeGenericType(elementType,typeof(object));
    var genericCacheType = typeof(Dictionary<,>).MakeGenericType(typeof(string), genericGetterType);
    var genericCacheConstructor = genericCacheType.GetConstructor(new Type[] { });
    genericMethod.Invoke(null, new object[] { objects, props, tod, genericCacheConstructor.Invoke(new object[] { }) });
}
于 2013-07-15T19:46:03.767 回答
1

我做了一个简单的测试,将问题替换为.GetValue执行简单分配的函数(“如果属性的名称是 blabla,则值是 Object.blabla”)。测试仅包含函数/变量/属性的简单版本和允许完全控制迭代次数的循环。结果肯定令人惊讶:新方法快了 10 倍!请记住,在我的原始测试(50000 次迭代)中,时间是 2276(旧)与 234(新)。对于不同的情况,这种差异保持不变;例如,对于 8000 次迭代,它提供 358 毫秒与 36 毫秒。我已经在一台功能强大的计算机和 C# winforms 上完成了这些测试;@Xaisoft 可以拿下面的代码,在他的特定条件下进行测试并告诉结果。

编码:

 private void Form1_Load(object sender, EventArgs e)
 {
     List<List> var = new List<List>();

     List var1 = new List();
     var1.var = 1;
     var1.var2 = 1;
     var1.var3 = 1;
     var1.var4 = 1;
     var1.var5 = 1;

     List var2 = new List();
     var2.var = 1;
     var2.var2 = 1;
     var2.var3 = 1;
     var2.var4 = 1;
     var2.var5 = 1;

     List var3 = new List();
     var3.var = 1;
     var3.var2 = 1;
     var3.var3 = 1;
     var3.var4 = 1;
     var3.var5 = 1;

     List var4 = new List();
     var4.var = 1;
     var4.var2 = 1;
     var4.var3 = 1;
     var4.var4 = 1;
     var4.var5 = 1;

     var.Add(var1);
     var.Add(var2);
     var.Add(var3);
     var.Add(var4);

     InitializeData(var, typeof(List).GetProperties());
 }

 private static void InitializeData(List<List> objects, PropertyInfo[] props)
 {
     DateTime start = DateTime.Now;

     int count = 0;
     do
     {
         count = count + 1;
         foreach (var item in objects)
         {

             foreach (var p in props)
             {
                 object returnData = p.GetValue(item, null); //returnProps(p.Name, item);
             }
         }

     } while (count < 50000);


     TimeSpan timer = new TimeSpan();
     timer = DateTime.Now.Subtract(start);
 }

 private class List
 {
     public int var { set; get; }
     public int var2 { set; get; }
     public int var3 { set; get; }
     public int var4 { set; get; }
     public int var5 { set; get; }
     public int var6 { set; get; }
     public int var7 { set; get; }
     public int var8 { set; get; }
     public int var9 { set; get; }
     public int var10 { set; get; }
     public int var11 { set; get; }
     public int var12 { set; get; }
     public int var13 { set; get; }
     public int var14 { set; get; }
 }
 private static object returnProps(string propName, List curObject)
 {
     if (propName == "var")
     {
         return curObject.var;
     }
     else if (propName == "var2")
     {
         return curObject.var2;
     }
     else if (propName == "var3")
     {
         return curObject.var3;
     }
     else if (propName == "var4")
     {
         return curObject.var4;
     }
     else if (propName == "var5")
     {
         return curObject.var5;
     }
     else if (propName == "var6")
     {
         return curObject.var6;
     }
     else if (propName == "var7")
     {
         return curObject.var7;
     }
     else if (propName == "var8")
     {
         return curObject.var8;
     }
     else if (propName == "var9")
     {
         return curObject.var9;
     }
     else if (propName == "var10")
     {
         return curObject.var10;
     }
     else if (propName == "var11")
     {
         return curObject.var11;
     }
     else if (propName == "var12")
     {
         return curObject.var12;
     }
     else if (propName == "var13")
     {
         return curObject.var13;
     }
     else if (propName == "var14")
     {
         return curObject.var14;
     }

     return new object();
 }

最后说明:我希望人们能够更笼统地理解如此令人印象深刻的结果,而不仅仅是应用于.GetValue. 如今,计算机可以处理很多事情,您实际上并不需要最大化每个位的性能,这是真的。另一方面,如果您遇到性能问题并且需要以更相关的方式“节省资源”,则应将改进重点放在“越简单,越快”的想法上。我已经使用相关数量的ListsDictionaries对代码进行了性能改进,即使在每次更改之后(List变成传统的Array),结果也很明显。你不必在这方面过于危言耸听,但如果被要求,ListArray更高(并且两个元素基本相同)。多维数组、长数组等也是如此。

------ 更详细的性能分析

尽管我从一开始就非常清楚地表达了我的观点(只是一个必须适应每种情况的想法),但我确实理解我的主张(快 10 倍)确实需要一个正确的定义。我一直在不同条件下进行测试,结果如下:

注意:上述结果由 32 位可执行文件输出;以下所有内容均来自 64 位。我观察到.GetValue从 32 位迁移到 64 位时性能有所提高。上述结果的更新 64 位版本为 (ms):

                      GetValue       Direct Assignation     
50000 iterations ->    1197                 157
80000 iterations ->    1922                 253
100000 iterations ->   2354                 310

因此,该比率从 10 倍变为 7.5 倍。

我开始增加属性的数量(每次都在 64 位上)并且GetValue变得越来越好。结果:

28 Properties
                          GetValue       Direct Assignation     
    50000 iterations ->    2386                552
    80000 iterations ->    3857                872

Aver. ratio = 4.37

50 Properties
                          GetValue       Direct Assignation     
    50000 iterations ->    4292                1707
    80000 iterations ->    6772                2711

Aver. ratio = 2.475

我不确定改进是否GetValue会继续,并且会达到比简单方法更好的地步,但谁在乎呢?在这一点上,很明显,越来越多的属性与简单化的方法背道而驰,所以是时候尝试一种不同的(同样非常简单的)替代方案:存储所有属性的全局数组。

  private static int[,] List0;

与给定属性并行填充(即,当object.propX = any value数组中的相应位置也被填充时)并由对象/属性位置(第一个对象、第三个属性等)引用。从逻辑上讲,这有对象数量的限制(将第一个维度增加到 1000 以上听起来并不推荐),但您可能依赖于不同的数组(一个存储从第一个对象到第 1000 个对象,另一个从第 1001 个存储到第 2000 个对象, ETC。); 您可以设置一个函数,将对象名称作为参数并返回相应的数组。

主循环中的修改:

int countObject = -1;
foreach (var item in objects)
{
    countObject = countObject + 1;
    int countProp = -1;
    foreach (var p in props)
    {
        countProp = countProp + 1;
        object returnData = List0[countObject, countProp];
    }
}

通过在上述案例中运行这种新方法,我得到:

50 Properties
                         GetValue           2D Array    
   80000 iterations ->    6772                155

Aver. ratio = 45.146

多一个:

70 Properties
                          GetValue          2D Array     
    80000 iterations ->    10444               213

Aver. ratio = 49.06

我在这里停止了我的测试。我想这足以证明我的观点。

不同的方法在不同的条件下提供不同的性能,因此了解一种情况的理想配置的最佳方法是实际测试它。依靠终极真理很少是解决问题的最佳方法(尽管我可能错了……仍在等待 DmitryG 的答复以测试他在不同条件下的解决方案)。因此,在测试条件下,对于属性数量相对较少(即低于 20)的情况,原始的简单化方法似乎是可以接受的;在此之上,所需的硬编码工作似乎不值得,依赖不同的替代方案(如我提出的 2D 数组)会更好。在任何情况下,GetValue显然都提供了糟糕的性能,可以通过许多不同的方式进行改进。

我希望我不需要再次更新这个答案:)

于 2013-07-15T18:47:36.473 回答
0

继续上面的帖子:您的代码构建了一个属性名称和(格式化)值的字典。所以我们只需要一个 List 作为输入。从 T 我们可以推导出所有信息。

    public Dictionary<string, object> ExtractParameterNameAndValue<T>(List<T> colleciton)
        where T : class
    {
        var result = new Dictionary<string, object>();

        // out of the loop - generate getters
        var properties = typeof(T).GetProperties(BindingFlags.Public | BindingFlags.Instance);
        var getterList = new List<Func<T,object>>();
        foreach (var p in properties)
        {
            getterList.Add(MyStatic.BuildUntypedGetter<T>(p));
        }

        // Array of getters
        var getters = getterList.ToArray(); // improving performance (?) - never use Dictionary
        // Corresponding array of Names
        var names = properties.Select(p => p.Name).ToArray();

        // iterate all data
        int counter = 0;
        foreach (var item in colleciton)
        {
            for (int i = 0; i< getters.Length; i++)
            {
                var name = names[i]; // name from property
                var value = getters[i](item);  // value from getter-call
                result.Add(counter + " " + name, value); 
            }
            counter++;
        }

        return result; ;
    }

BuildUntypedGetter() 方法就像

   // see http://flurfunk.sdx-ag.de/2012/05/c-performance-bei-der-befullungmapping.html
   public static Func<T, object> BuildUntypedGetter<T>(PropertyInfo propertyInfo)
    {
        var targetType = propertyInfo.DeclaringType;
        var methodInfo = propertyInfo.GetGetMethod();
        var returnType = methodInfo.ReturnType;

        var exTarget = Expression.Parameter(targetType, "t");
        var exBody = Expression.Call(exTarget, methodInfo);
        var exBody2 = Expression.Convert(exBody, typeof(object));

        var lambda = Expression.Lambda<Func<T, object>>(exBody2, exTarget);

        var action = lambda.Compile();
        return action;
    }

无需在调用中指定类型。它是通过类型推断来检测的。

       var accountList = new List<Account>()
        {
            new Account { Name = "X1", Name2 ="X2"},
            new Account { Name = "X3", Name2 ="X4"},
            new Account { Name = "X5", Name2 ="X6"},
        };

        var result = ExtractParameterNameAndValue(accountList);
于 2013-07-17T14:10:23.270 回答