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);}#endregionvar 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

List.Exists

List.Find

Dictionary.TryGetValue

HashSet.Contains