C# Linq.FirstOrDefault、Linq.Where、Linq.AsParallel、List.Exists、List.Find、Dictionar.TryGetValue、HashSet.Contains 性能的比较

今天我们来比较一下集合检索方法性能更优问题，测试代码

public class Entity
{
public int Id { get; set; }
public int No { get; set; }
public string Col1 { get; set; }
public string Col2 { get; set; }
public string Col3 { get; set; }
public string Col4 { get; set; }
public string Col5 { get; set; }
public string Col6 { get; set; }
public string Col7 { get; set; }
public string Col8 { get; set; }
public string Col9 { get; set; }
public string Col10 { get; set; }
}
static void TestFindVelocity(int totalDataCount, int executeCount)
{
#region 构造数据
List<Entity> datas = new List<Entity>();
for (int i = 0; i < totalDataCount; i++)
{
var item = new Entity
{
No = i + 1,
Col1 = Guid.NewGuid().ToString("N"),
Col2 = Guid.NewGuid().ToString("N"),
Col3 = Guid.NewGuid().ToString("N"),
Col4 = Guid.NewGuid().ToString("N"),
Col5 = Guid.NewGuid().ToString("N"),
Col6 = Guid.NewGuid().ToString("N"),
Col7 = Guid.NewGuid().ToString("N"),
Col8 = Guid.NewGuid().ToString("N"),
Col9 = Guid.NewGuid().ToString("N"),
Col10 = Guid.NewGuid().ToString("N"),
};
datas.Add(item);
}
#endregion
var dicDatas = datas.ToDictionary(x => x.No);
var hashSetDatas = datas.ConvertAll<Tuple<int, int>>(x => new Tuple<int, int>(x.No, x.No + 1000)).ToHashSet();
Stopwatch sw = new Stopwatch();
Random random = new Random();
Entity searchResult = null;
bool searchResultBool = false;
// 每次查询索引
List<int> indexs = Enumerable.Range(1, executeCount).Select(x => random.Next(1, totalDataCount)).ToList();

sw.Start();
for (int i = 0; i < executeCount; i++)
{
searchResult = datas.FirstOrDefault(x => x.No == indexs[i]);
}
sw.Stop();
Console.WriteLine($"list FirstOrDefault 耗时：{sw.ElapsedMilliseconds}");

sw.Restart();
for (int i = 0; i < executeCount; i++)
{
searchResult = datas.Where(x => x.No == indexs[i]).First();
}
sw.Stop();
Console.WriteLine($"list Where+First 耗时：{sw.ElapsedMilliseconds}");

sw.Restart();
for (int i = 0; i < executeCount; i++)
{
searchResultBool = datas.Exists(x => x.No == indexs[i]);
}
sw.Stop();
Console.WriteLine($"list Exist 耗时：{sw.ElapsedMilliseconds}");

sw.Restart();
for (int i = 0; i < executeCount; i++)
{
searchResult = datas.Find(x => x.No == indexs[i]);
}
sw.Stop();
Console.WriteLine($"list Find 耗时：{sw.ElapsedMilliseconds}");

sw.Restart();
for (int i = 0; i < executeCount; i++)
{
dicDatas.TryGetValue(indexs[i], out searchResult);
}
sw.Stop();
Console.WriteLine($"dictionary TryGetValue 耗时：{sw.ElapsedMilliseconds}");

sw.Restart();
for (int i = 0; i < executeCount; i++)
{
searchResultBool = hashSetDatas.Contains(new Tuple<int, int>(indexs[i], indexs[i] + 1000));
}
sw.Stop();
Console.WriteLine($"Hashset contains 耗时：{sw.ElapsedMilliseconds}");
}

结果

(集合数量，测试次数) Linq.FirstOrDefault Linq.Where+First