ConcurrentDictionary.TryAdd 会失败吗

使用ConcurrentDictionary.TryAdd方法时，尝试将键值对添加到并发字典中，但是有时会失败。这种情况通常发生在并发环境下，多个线程同时尝试添加相同的键值对到字典中。在这种情况下，只有一个线程能够成功添加键值对，而其他线程则会返回失败的结果。

csharp
using System;
using System.Collections.Concurrent;
using System.Threading.Tasks;
class Program
{
    static ConcurrentDictionary dictionary = new ConcurrentDictionary();
    static void Main()
    {
        // 启动多个任务同时尝试添加相同的键值对
        Task[] tasks = new Task[5];
        for (int i = 0; i < tasks.Length; i++)
        {
            tasks[i] = Task.Run(() => AddKeyValuePair(i, "Value"));
        }
        Task.WaitAll(tasks);
        // 输出字典中的所有键值对
        foreach (var kvp in dictionary)
        {
            Console.WriteLine($"Key: {kvp.Key}, Value: {kvp.Value}");
        }
    }
    static void AddKeyValuePair(int key, string value)
    {
        bool success = dictionary.TryAdd(key, value);
        if (success)
        {
            Console.WriteLine($"Thread {Task.CurrentId} added key-value pair successfully.");
        }
        else
        {
            Console.WriteLine($"Thread {Task.CurrentId} failed to add key-value pair.");
        }
    }
}

csharp
using System;
using System.Collections.Concurrent;
using System.Threading.Tasks;
class Program
{
    static ConcurrentDictionary dictionary = new ConcurrentDictionary();
    static void Main()
    {
        // 启动多个任务同时尝试添加相同的键值对
        Task[] tasks = new Task[5];
        for (int i = 0; i < tasks.Length; i++)
        {
            tasks[i] = Task.Run(() => GetOrAddKeyValuePair(i, "Value"));
        }
        Task.WaitAll(tasks);
        // 输出字典中的所有键值对
        foreach (var kvp in dictionary)
        {
            Console.WriteLine($"Key: {kvp.Key}, Value: {kvp.Value}");
        }
    }
    static void GetOrAddKeyValuePair(int key, string value)
    {
        string result = dictionary.GetOrAdd(key, value);
        if (result == value)
        {
            Console.WriteLine($"Thread {Task.CurrentId} added key-value pair successfully.");
        }
        else
        {
            Console.WriteLine($"Thread {Task.CurrentId} failed to add key-value pair.");
        }
    }
}