C# 并发容器之ConcurrentDictionary与普通Dictionary带锁的性能对比

static void Main(string[] args)
{
var concurrentDictionary = new ConcurrentDictionary<int, string>();
var dictionary = new Dictionary<int, string>();

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: 00:00:00.0633939
sw.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: 00:00:00.0286066
sw.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;