MySqlPoolManager.GetPool 报错An item with the same key has already been added.

Question

报错：

System.ArgumentException: An item with the same key has already been added. Key: database=timsdb;server=127.0.0.1;port=3306;user id=admin;password=123456;characterset=utf8;allowuservariables=True;defaultcommandtimeout=600;sslmode=Disabled
at System.Collections.Generic.Dictionary`2.TryInsert(TKey key, TValue value, InsertionBehavior behavior)
at MySql.Data.MySqlClient.MySqlPoolManager.GetPool(MySqlConnectionStringBuilder settings)
at MySql.Data.MySqlClient.MySqlConnection.Open()

环境

数据库版本：Mysql Ver 8.0.30 for Win64 on x86_64 (MySQL Community Server - GPL)
mysql.data.dll 引用版本 8.0.31

代码：

var providerName="MySql.Data.MySqlClient";
var _connectionString="database=timsdb;server=127.0.0.1;port=3306;user id=admin;password=123456;characterset=utf8;allowuservariables=True;defaultcommandtimeout=600;sslmode=Disabled";
          DbProviderFactory _dbProviderFactory = DbProviderFactories.GetFactory(providerName);
       Database     _database = new Database(_connectionString, _dbProviderFactory);
          DbConnection  _dbConnection = _dbProviderFactory.CreateConnection();
        _dbConnection.ConnectionString = _connectionString;

while(true)
{
           if (_dbConnection == null || IsDisposed)
            {
                _dbTransaction = null;
                _dbConnection = _dbProviderFactory.CreateConnection();
                _dbConnection.ConnectionString = _connectionString;
            }

            if (_dbConnection.State == ConnectionState.Open)
            {
                continue;
            }
          _dbConnection.Open();
}

排查思路

1、连接过多导致？报错不一致
2、连接关闭过于频繁？

Answer 1

这个错误消息表明，你已经在字典中添加了与键 database=timsdb;server=127.0.0.1;port=3306;user id=admin;password=123456;characterset=utf8;allo 相同的项，并且该键值对已存在。在 MySql.Data.MySqlClient.MySqlPoolManager.GetPool 函数中，你需要确保连接字符串是唯一的。你可以尝试给字符串添加一个随机数，以保证连接字符串的唯一性，如下所示：

var connectionString = "database=timsdb;server=127.0.0.1;port=3306;user id=admin;password=123456;characterset=utf8;allowuservariables=True;defaultcommandtimeout=600;sslmode=Disabled;" + Guid.NewGuid().ToString();