C#并发容器之ConcurrentDictionary与普通Dictionary带锁性能详解 C#并发容器之ConcurrentDictionary与

结果已经写在注释中

static void Main(string[] args){var concurrentDictionary = new ConcurrentDictionary(); var dictionary = new Dictionary(); var sw = new Stopwatch(); sw.Start(); for (int i = 0; i < 1000000; i++){lock (dictionary){dictionary[i] = Item; }} sw.Stop(); Console.WriteLine("wrinting to dictionary with a lock: {0}", sw.Elapsed); //wrinting to dictionary with a lock: 00:00:00.0633939sw.Restart(); for (int i = 0; i < 1000000; i++){concurrentDictionary[i] = Item; }sw.Stop(); Console.WriteLine("wrinting to a concurrent dictionary: {0}", sw.Elapsed); //wrinting to a concurrent dictionary: 00:00:00.2889851//对于写入操作并发词典要比普通带锁词典要慢sw.Restart(); for (int i = 0; i < 1000000; i++){lock (dictionary){CurrentItem = dictionary[i]; }}sw.Stop(); Console.WriteLine("reading from dictionary with a lock: {0}", sw.Elapsed); //reading from dictionary with a lock: 00:00:00.0286066sw.Restart(); for (int i = 0; i < 1000000; i++){CurrentItem = concurrentDictionary[i]; }sw.Stop(); Console.WriteLine("reading from a concurrent dictionary: {0}", sw.Elapsed); //reading from a concurrent dictionary: 00:00:00.0196372//对于读取操作并发词典要比普通带锁词典要快//concurrentDictionary采用细粒度锁定[fine-grained locking]//普通带锁dictionary采用粗粒度锁定[coarse-grained locking]//在多核多线程的情况下concurrentDictionary将有更好的性能表现sw.Restart(); Console.ReadKey(); } const string Item = "Dictionary item"; public static string CurrentItem;

补充：C#中普通字典（Dictionary）、并发字典（ConcurrentDictionary）、和哈希表（Hashtable）读写性能比较
一、说明 【C#并发容器之ConcurrentDictionary与普通Dictionary带锁性能详解】程序有时候需要并发多线程操作，多线程读取同一个容器内的东西是可以的，但是如果需要修改及写入到同一容器内，会有索引失败的问题，即两个进程同时向同一个位置写入内容，这种情况下需要通过lock（var），将容器锁定，也可以直接使用可并发读写的容器（ConcurrentDictionary）
测试分2部分，一次是写入操作，包含带锁写入和不带锁写入，其中每个里面又细分为写入字符串和写入一个类，还有一次是遍历操作，同样包含带锁读和不带锁读，其中也分为读取字符串和读取类。
二、测试结果

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2.1、写入用时

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2.2、遍历用时

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2.3、结论
对于写入操作速度：普通词典 > HashTable > 并发词典
对于读操作速度：并发字典 > 带锁字典 > HashTable
无论普通字典还是HashTable，带锁花费的时间都要比不带锁慢，为了线程安全，肯定要牺牲时间的。
所以如果需要自己写入的话，推荐带锁普通字典，读写速度都很均衡。
三、测试代码如下

using System; using System.Collections; using System.Collections.Concurrent; using System.Collections.Generic; using System.ComponentModel; using System.Diagnostics; using System.Linq; using System.Text; using System.Threading; using System.Threading.Tasks; namespace BaseMultiThread{class Program{static void Main(string[] args){ConcurrentDictionary _CctDic= new ConcurrentDictionary(); ConcurrentDictionary _CctDicClass = new ConcurrentDictionary(); Dictionary _Dic = new Dictionary(); Dictionary _DicClass = new Dictionary(); Hashtable _Ht = new Hashtable(); Hashtable _HtClass = new Hashtable(); string _CurrentItem = ""; const string _Item = "字符串"; const int _NUM = 10000000; //执行次数 Student _CurrentStudent = null; Student student = new Student { Name = _Item, Age = 23 }; Stopwatch _SW = new Stopwatch(); //字符串写入字典（无锁）_SW.Start(); for (int i = 0; i < _NUM; i++){_Dic[i] = _Item; }_SW.Stop(); Console.WriteLine("向字典写入【字符串】不添加锁（Lock）花费时间为:{0} 毫秒", _SW.Elapsed.TotalMilliseconds); //字符串写入字典（有锁）_Dic = new Dictionary(); _SW.Restart(); for (int i = 0; i < _NUM; i++){lock (_Dic){_Dic[i] = _Item; }}_SW.Stop(); Console.WriteLine("向字典写入【字符串】添加锁（Lock）花费时间为:{0} 毫秒", _SW.Elapsed.TotalMilliseconds); //类写入字典（无锁）_SW.Restart(); for (int i = 0; i < _NUM; i++){_DicClass[i] = student; }_SW.Stop(); Console.WriteLine("向子典写入【学生类】不添加锁（Lock）花费时间为:{0} 毫秒", _SW.Elapsed.TotalMilliseconds); //类写入字典（有锁）_DicClass = new Dictionary(); _SW.Restart(); for (int i = 0; i < _NUM; i++){lock (_DicClass){_DicClass[i] = student; }}_SW.Stop(); Console.WriteLine("向子典写入【学生类】添加锁（Lock）花费时间为:{0} 毫秒", _SW.Elapsed.TotalMilliseconds); Console.WriteLine("----------------------------------------------------"); //字符串写入HashTable（无锁）_SW.Restart(); for (int i = 0; i < _NUM; i++){_Ht[i] = _Item; }_SW.Stop(); Console.WriteLine("向HashTable写入【字符串】不添加锁（Lock）花费时间为:{0} 毫秒", _SW.Elapsed.TotalMilliseconds); //字符串写入HashTable（有锁）_Ht = new Hashtable(); _SW.Restart(); for (int i = 0; i < _NUM; i++){lock (_Ht){_Ht[i] = _Item; }}_SW.Stop(); Console.WriteLine("向HashTable写入【字符串】添加锁（Lock）花费时间为:{0} 毫秒", _SW.Elapsed.TotalMilliseconds); //类写入HashTable（无锁）_SW.Restart(); for (int i = 0; i < _NUM; i++){_HtClass[i] = student; }_SW.Stop(); Console.WriteLine("向HashTable写入【学生类】不添加锁（Lock）花费时间为:{0} 毫秒", _SW.Elapsed.TotalMilliseconds); //类写入HashTable（有锁）_SW.Restart(); for (int i = 0; i < _NUM; i++){lock (_HtClass){_HtClass[i] = student; }}_SW.Stop(); Console.WriteLine("向HashTable写入【学生类】添加锁（Lock）花费时间为:{0} 毫秒", _SW.Elapsed.TotalMilliseconds); Console.WriteLine("----------------------------------------------------------"); //字符串写入ConcurrentDictionary_SW.Restart(); for (int i = 0; i < _NUM; i++){_CctDic[i] = _Item; }_SW.Stop(); Console.WriteLine("向ConcurrentDictionary写入【字符串】花费时间为:{0} 毫秒", _SW.Elapsed.TotalMilliseconds); //类写入ConcurrentDictionary_SW.Restart(); for (int i = 0; i < _NUM; i++){_CctDicClass[i] = student; }_SW.Stop(); Console.WriteLine("向ConcurrentDictionary写入【学生类】花费时间为:{0} 毫秒", _SW.Elapsed.TotalMilliseconds); Console.WriteLine("--------------------------------------------------------"); //遍历普通字典（无锁）_SW.Restart(); for (int i = 0; i < _NUM; i++){_CurrentItem = _Dic[i]; }_SW.Stop(); Console.WriteLine("遍历【普通】字典（无锁）花费时间为:{0} 毫秒", _SW.Elapsed.TotalMilliseconds); //遍历普通字典（有锁）_SW.Restart(); for (int i = 0; i < _NUM; i++){lock (_Dic){_CurrentItem = _Dic[i]; }}_SW.Stop(); Console.WriteLine("遍历【普通】字典（有锁）花费时间为:{0} 毫秒", _SW.Elapsed.TotalMilliseconds); //遍历类字典（无锁）_SW.Restart(); for (int i = 0; i < _NUM; i++){_CurrentStudent = _DicClass[i]; }_SW.Stop(); Console.WriteLine("遍历【学生类】字典（无锁）花费时间为:{0} 毫秒", _SW.Elapsed.TotalMilliseconds); //遍历类字典（有锁）_SW.Restart(); for (int i = 0; i < _NUM; i++){lock (_Dic){_CurrentStudent = _DicClass[i]; }}_SW.Stop(); Console.WriteLine("遍历【学生类】字典（有锁）花费时间为:{0} 毫秒", _SW.Elapsed.TotalMilliseconds); Console.WriteLine("--------------------------------------------------------"); //遍历HashTable（无锁）_SW.Restart(); for (int i = 0; i < _NUM; i++){_CurrentItem = _Ht[i].ToString(); }_SW.Stop(); Console.WriteLine("遍历【HashTable】字典（无锁）花费时间为:{0} 毫秒", _SW.Elapsed.TotalMilliseconds); //遍历HashTable（有锁）_SW.Restart(); for (int i = 0; i < _NUM; i++){lock (_Dic){_CurrentItem = _Ht[i].ToString(); }}_SW.Stop(); Console.WriteLine("遍历【HashTable】字典（有锁）花费时间为:{0} 毫秒", _SW.Elapsed.TotalMilliseconds); //遍历HashTable类（无锁）_SW.Restart(); for (int i = 0; i < _NUM; i++){_CurrentStudent = (Student)_HtClass[i]; }_SW.Stop(); Console.WriteLine("遍历【HashTable学生类】字典（无锁）花费时间为:{0} 毫秒", _SW.Elapsed.TotalMilliseconds); //遍历HashTable类（有锁）_SW.Restart(); for (int i = 0; i < _NUM; i++){lock (_Dic){_CurrentStudent = (Student)_HtClass[i]; }}_SW.Stop(); Console.WriteLine("遍历【HashTable学生类】字典（有锁）花费时间为:{0} 毫秒", _SW.Elapsed.TotalMilliseconds); Console.WriteLine("--------------------------------------------------------"); //遍历ConCurrent字典_SW.Restart(); for (int i = 0; i < _NUM; i++){_CurrentItem = _CctDic[i]; }_SW.Stop(); Console.WriteLine("遍历【ConCurrent字典】（字符串）花费时间为:{0} 毫秒", _SW.Elapsed.TotalMilliseconds); //遍历ConCurrent字典（类）_SW.Restart(); for (int i = 0; i < _NUM; i++){_CurrentStudent = _CctDicClass[i]; }_SW.Stop(); Console.WriteLine("遍历【ConCurrent字典】（学生类）花费时间为:{0} 毫秒", _SW.Elapsed.TotalMilliseconds); Console.WriteLine("--------------------------------------------------------"); _SW.Restart(); Console.WriteLine("-------------------结束---------------------------"); Console.ReadLine(); }}//Class_endpublic class Student{public string Name; public int Age; }}

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