通過測試發現，多線程操做都是安全的。甚至包括在遍歷的時候，進行刪除操做安全
class Program { private static readonly ConcurrentDictionary<int, int> Dictionary = new ConcurrentDictionary<int, int>(); private static readonly List<string> AddSuccessfully = new List<string>(); private static readonly List<string> RemoveSuccessfully = new List<string>(); private static readonly List<string> IterateString = new List<string>(); private static int _tryRemoveCount; private static readonly Random Random = new Random(); static void Main(string[] args) { try { int j = 0; for (int i = 1; i <= 12; i++) { j++; Thread thread; if (j == 1) { thread = new Thread(DoTask1); } else if(j == 2) { thread = new Thread(DoTask2); } else if (j == 3) { thread = new Thread(DoTask3); j = 0; } else { throw new Exception(); } thread.IsBackground = false; thread.Start(i); } Console.WriteLine("======"); int timeout = 0; while (AddSuccessfully.Count != 100) { timeout++; Thread.Sleep(1000); if (timeout > 5) { break; } } timeout = 0; while (_tryRemoveCount != 5) { timeout++; Thread.Sleep(1000); if (timeout > 5) { break; } } Console.WriteLine($"addSuccessfully.Count = {AddSuccessfully.Count}"); foreach (var item in AddSuccessfully) { Console.WriteLine(item); } Console.WriteLine($"removeSuccessfully.Count = {RemoveSuccessfully.Count}"); foreach (var item in RemoveSuccessfully) { Console.WriteLine(item); } Console.WriteLine($"IterateString.Count = {IterateString.Count}"); foreach (var item in IterateString) { Console.WriteLine(item); } } catch (Exception ex) { Console.WriteLine(ex); } finally { Console.ReadLine(); } } public static void DoTask1(object obj) { Console.WriteLine($"DoTask1 with {obj} Thread id = {Thread.CurrentThread.ManagedThreadId}"); for (int i = 0; i < 100; i++) { var flag = Dictionary.TryAdd(i,i); if (flag) { AddSuccessfully.Add($"DoTask1 with {obj} add {i} successfully {DateTime.Now:yyyy-MM-dd HH:mm:ss.fff}"); //Console.WriteLine(); } Thread.Sleep(1); } } public static void DoTask2(object obj) { _tryRemoveCount++; Console.WriteLine( $"DoTask2 with {obj} Thread id = {Thread.CurrentThread.ManagedThreadId}, count = {Dictionary.Count}"); var toRemove = Random.Next(0, 100); for (int i = 0; i < 100; i++) { var flag = Dictionary.TryRemove(toRemove, out _); if (flag) { RemoveSuccessfully.Add($"DoTask2 with {obj} remove {toRemove} successfully. {DateTime.Now:yyyy-MM-dd HH:mm:ss.fff}"); } Thread.Sleep(1); } } public static void DoTask3(object obj) { _tryRemoveCount++; Console.WriteLine( $"DoTask3 with {obj} Thread id = {Thread.CurrentThread.ManagedThreadId}, count = {Dictionary.Count}"); foreach (var item in Dictionary) { IterateString.Add($"DoTask3 with {obj} iterate {item.Key} {DateTime.Now:yyyy-MM-dd HH:mm:ss.fff}"); Thread.Sleep(2); } } }