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异步odbc似乎是同步的

async-await ado.net asynchronous c#

doktron · 技术社区 · 8 年前

我试图进行异步数据库查询,但当我测试代码时,它似乎是同步的。我已将问题隔离到查询函数。我不知道我做错了什么,我对aync/await功能相当陌生,所以我可能做了一些愚蠢的事情:)

这是失败的代码:(我正在使用postgresql的本地安装)

    public static void Main()
    {
        Task.Run(async () => await MainAsync()).GetAwaiter().GetResult();
    }

    public static async Task MainAsync()
    {
        await TestDbSleep(5);
    }

    public static async Task TestDbSleep(int seconds)
    {
        Console.WriteLine("{0} Starting tasks!", DateTime.Now.ToString("HH:mm:ss"));
        var tasks = new[] { DbSleep(5, "first"), DbSleep(seconds, "second"), DbSleep(seconds, "third") };
        Console.WriteLine("All tasks started!");
        await Task.WhenAll(tasks);
        Console.WriteLine("{0} All tasks done!", DateTime.Now.ToString("HH:mm:ss"));
    }

    public static async Task<DbDataReader> DbSleep(int seconds, string name)
    {
        Console.WriteLine("Starting {0}!", name);
        var result = await Query("SELECT * FROM pg_sleep(?)", new OdbcParameter("seconds", seconds));
        Console.WriteLine("{0} done!", name);
        return result;
    }

    public static async Task<DbDataReader> Query(string sql, params OdbcParameter[] parameters)
    {   
        using (var dbConn = new OdbcConnection(ConfigurationManager.ConnectionStrings["MainConnectionString"].ConnectionString))
        {
            await dbConn.OpenAsync();
            var command = new OdbcCommand(sql, dbConn);
            if (parameters != null)
            {
                foreach (var parameter in parameters)
                {
                    command.Parameters.Add(parameter);
                }
            }
            return await command.ExecuteReaderAsync();
        }
    }

当我运行此代码时,我得到以下输出:

09:29:20 Starting tasks!
Starting first!
first done!
Starting second!
second done!
Starting third!
third done!
All tasks started!
09:29:36 All tasks done!

我试图用等待任务替换对查询函数的调用。延迟(秒*1000),当我这样做时,代码异步执行如下:

09:29:15 Starting tasks!
Starting first!
Starting second!
Starting third!
All tasks started!
third done!
second done!
first done!
09:29:20 All tasks done!