/// <summary>
/// 从连接池中获取可用的数据库连接，如果无法获取，将抛出异常
/// </summary>
/// <returns></returns>
public DbConnection GetConnection()
{
using (easyLock.Write())
{
var connS = RandomConnectionString();
var conn = new NpgsqlConnection(connS.ConnectionString);
return(conn);
}
}
