连接池应该比保持连接打开的速度要慢得多

Question

作为我的上一个问题：如何保持到数据库直到屏幕关闭？

？

首先，让我对我不解释我的情况表示歉意。

好吧，我的情况最多可更新一百个记录。我使用For loop创建一个真实的工作并记录其结果。

private void button1_Click(object sender, EventArgs e)
{
    int i;
    KeyEventArgs keyEvent = new KeyEventArgs(Keys.Enter); //Create keydown event 
    Performance perf = new Performance(); //Class for measure time and logging
    perf.Start(); //Start stopwatch
    for (i = 1; i <= 100; i++)
    {
        txtLotNo.Text = i.ToString("0000000000") + "$01";   //Generate input ID
        txtLotNo_KeyDown(sender, keyEvent); //Fire keydown event
    }
    perf.Stop();    //Stop stopwatch
    perf.Log(frmInvCtrl.appPath,"Stock In (Stay connected)- " + frmInvCtrl.instance);   //Logging
}

这是一个表演类。

class Performance
{
    private Stopwatch _sw = new Stopwatch();    //Create stopwatch property
    public double GetWatch
    {
        get
        {
            return this._sw.ElapsedMilliseconds;
        }
    }
    public void Start()
    {
        Stop();
        _sw.Reset();
        _sw.Start();
    }
    public void Stop()
    {
        if (_sw.IsRunning)
        {
            _sw.Stop();
        }
    }
    public void Log(string path,string menu)
    {
        string logName = path + "\Log_" + System.DateTime.Now.ToString("yyyyMMdd") + ".txt";
        string logDetail = System.DateTime.Now.ToString("yyyy/MM/dd hh:mm:ss") + " - [" + menu + "] "
            + "Process 100 record in [" + (((double)_sw.ElapsedMilliseconds / 1000)).ToString() + "] seconds";
        using(StreamWriter writer = new StreamWriter(logName,true))
        {
            writer.WriteLine(logDetail);    //wirtelog
        }
    }
}

这些是日志结果

2017/02/19 08:16:05 - [Stock In - On Cloud] Process 100 record in [68.352] seconds
2017/02/19 08:17:34 - [Stock In - On Cloud] Process 100 record in [70.184] seconds
2017/02/19 08:20:28 - [Stock In - On Cloud] Process 100 record in [56.66] seconds
2017/02/19 08:21:34 - [Stock In - On Cloud] Process 100 record in [60.605] seconds
2017/02/19 08:22:44 - [Stock In - On Cloud] Process 100 record in [68.27] seconds
2017/02/19 08:24:43 - [Stock In - Network Server] Process 100 record in [46.86] seconds
2017/02/19 08:26:05 - [Stock In - Network Server] Process 100 record in [31.746] seconds
2017/02/19 08:26:48 - [Stock In - Network Server] Process 100 record in [31.859] seconds
2017/02/19 08:27:32 - [Stock In - Network Server] Process 100 record in [31.003] seconds
2017/02/19 08:28:17 - [Stock In - Network Server] Process 100 record in [40.487] seconds
2017/02/19 08:32:42 - [Stock In (Stay connected)- On Cloud] Process 100 record in [18.196] seconds
2017/02/19 08:35:47 - [Stock In (Stay connected)- On Cloud] Process 100 record in [14.721] seconds
2017/02/19 08:36:30 - [Stock In (Stay connected)- On Cloud] Process 100 record in [15.903] seconds
2017/02/19 08:37:31 - [Stock In (Stay connected)- On Cloud] Process 100 record in [15.811] seconds
2017/02/19 08:38:15 - [Stock In (Stay connected)- On Cloud] Process 100 record in [16.4] seconds
2017/02/19 08:43:08 - [Stock In (Stay connected)- Network Server] Process 100 record in [13.09] seconds
2017/02/19 08:43:25 - [Stock In (Stay connected)- Network Server] Process 100 record in [13.03] seconds
2017/02/19 08:43:40 - [Stock In (Stay connected)- Network Server] Process 100 record in [13.051] seconds
2017/02/19 08:43:55 - [Stock In (Stay connected)- Network Server] Process 100 record in [12.992] seconds
2017/02/19 08:44:12 - [Stock In (Stay connected)- Network Server] Process 100 record in [14.953] seconds

我是通过连接池进行的。但是，在许多记录情况下，显示的这些结果保持在数据库中更快。

是否有适合这种情况的练习？

编辑：2017/02/21

这是打开表单时的打开连接：

private void frm_Load(object sender, EventArgs e) //Open menu
{
    ... //statement
    frmMain.sqlConn1 = new SqlConnection();
    frmMain.sqlConn1.ConnectionString = frmMain.connectionString1;
    frmMain.sqlConn1.Open();
    ... //statement
}

更新代码：

public static long ScanUpdate(string lotNo)
{
    string scanLotNo = "";
    int scanIndex = 0;
    if (!SplitBarcode(lotNo, ref scanLotNo, ref scanIndex))
    {
        //Invalid Barcode data
        return -919;
    }
    //Prepare sql command
    string updStatus = (frmMain.shelfScan) ? "05" : "10";
    string sql = <sql statement>
    try
    {
        using (SqlCommand sqlCmd = new SqlCommand(sql, frmMain.sqlConn1))   //frmMain.sqlConn1 is connection in form_Load()
        {
            if (sqlCmd.ExecuteNonQuery() <= 0)
            {
                //No row affect
                //frmMain.sndPlay.Play();
                return -99;
            }
            else
            {
                //Completed
                return 0;
            }
        }
    }
    catch
    {
        return 99;
    }
    finally
    {
    }
}

出口时处置连接

private void btnBack_Click(object sender, EventArgs e)
{
    frmMain.sqlConn1.Dispose();
    this.Close();
}

Answer 1

从单个线程的响应的角度来看，保持连接的速度将更快。连接池的目的是通过在线程之间共享新连接的费用，同时又不消耗共享SQL Server上过多的连接。

每当将连接释放到连接池，然后重复使用时，协议堆栈将呼叫SP_ResetConnection以清理服务器上的状态。您可以通过针对SQL Server运行Profiler Tract。

由于每个过程都有每个连接字符串的连接池，因此您只有在一个过程中存在连接的争论时，您才能从连接池中受益。

Answer 2

这里每个人都缺少的部分是其 Windows CE ，紧凑型版本上的开放连接并不罕见的打开连接可能真的很慢。

那就是说，那些时代看起来确实有些夸张。请参阅此质量检查的方法：如何使我的SQL Server CE连接更快地打开？

Answer 3

在许多领域中，您可以在上面的代码中遇到问题。

• 您正在创建一个SqlConnection实例。
• 您所有的事件处理程序都称为静态功能，该功能引用了一个SQLConnection实例。
• 您的活动处理程序不检查它们是否在主UI线程上运行。

SqlConnection类将自动在封面下的连接。当您调用close()函数时，连接只会返回池。您可以通过连接字符串中的属性来控制池行为。通过保留所有功能相同的连接对象，您将强迫它们序列化。

这是对某些连接字符串属性的引用。看看Connection Lifetime。

我将从form_load()函数中删除SqlConnection实例，然后写下ScanUpdate如下：

public static long ScanUpdate(string lotNo)
{
    string scanLotNo = "";
    int scanIndex = 0;
    if (!SplitBarcode(lotNo, ref scanLotNo, ref scanIndex))
    {
        //Invalid Barcode data
        return -919;
    }
    //Prepare sql command
    string updStatus = (frmMain.shelfScan) ? "05" : "10";
    string sql = <sql statement>
    try
    {
        using (SqlConnection conn = new SqlConection(frmMain.connectionString1)) {
            SqlCommand sqlCmd = new SqlCommand(sql, conn);
            if (sqlCmd.ExecuteNonQuery() <= 0)
            {
                //No row affect
                //frmMain.sndPlay.Play();
                return -99;
            }
            else
            {
                //Completed
                return 0;
            }
            conn.Close();
        }            
    }
    catch
    {
        return 99;
    }
}

对于您的*_Click事件处理程序功能，请确保检查是否需要重新启动该事件：

private void button1_Click(object sender, EventArgs e)
{
   if (this.InvokeRequired)
   {
      this.Invoke(new EventArgsDelegate(button1_Click), new object[] { sender, ea });
   }
   // Do some stuff
}

有关事件处理的更多详细信息，请参见此答案。