C# 线程池使用
使用C#线程池可以省去对线程的创建、销毁等操作，但是也不能很好的控制线程，这里是本人对线程池的理解，留下记录方便以后查询!
本DEMO用线程池多线程去读取Northwind所有表的数据与不用线程读取的时间差异
不用线程读取时间：
使用线程读取时间：
主要代码：
1 不使用线程读取代码：
1 private void button4_Click(object sender, EventArgs e) 2 { 3 if (listBox1.Items.Count > 0) 4 { 5 System.Diagnostics.Stopwatch singleThreadWatch = new System.Diagnostics.Stopwatch(); 6 singleThreadWatch.Start(); 7 tableCount = 0; 8 useTime = 0; 9 label1.Text = ""; 10 tabControl1.Controls.Clear(); 11 string[] list = new string[listBox1.Items.Count]; 12 for (int i = 0; i < listBox1.Items.Count; i++) 13 { 14 list[i] = listBox1.Items[i].ToString(); 15 } 16 17 if (list != null && list.Length > 0) 18 { 19 foreach (string item in list) 20 { 21 tableCount += 1; 22 23 using (SqlConnection con = new SqlConnection(connectionString)) 24 { 25 if (con.State != ConnectionState.Open) con.Open(); 26 string selectAllTableNameSQL = "select * from [" + item.ToString()+"]"; 27 using (SqlCommand sqlCmd = new SqlCommand(selectAllTableNameSQL, con)) 28 { 29 sqlCmd.CommandType = CommandType.Text; 30 SqlDataReader sqlDataRead = sqlCmd.ExecuteReader(); 31 if (null != sqlDataRead) 32 { 33 DataTable dt = new DataTable(); 34 dt.Load(sqlDataRead); 35 if (null != dt && dt.Rows.Count > 0) 36 { 37 DataGridView dgv = new DataGridView(); 38 dgv.ColumnHeadersHeightSizeMode = System.Windows.Forms.DataGridViewColumnHeadersHeightSizeMode.AutoSize; 39 dgv.Dock = System.Windows.Forms.DockStyle.Fill; 40 dgv.Location = new System.Drawing.Point(3, 3); 41 dgv.Name = "dataGridView" + item.ToString(); 42 dgv.RowTemplate.Height = 23; 43 44 dgv.DataSource = dt; 45 46 TabPage tb = new TabPage(); 47 tb.Controls.Add(dgv); 48 tb.Location = new System.Drawing.Point(4, 22); 49 tb.Name = "tabPage" + item.ToString(); 50 tb.Padding = new System.Windows.Forms.Padding(3); 51 tb.Size = new System.Drawing.Size(358, 446); 52 tb.Text = "tabPage" + item.ToString(); 53 tb.UseVisualStyleBackColor = true; 54 55 tabControl1.Controls.Add(tb); 56 Application.DoEvents(); 57 } 58 } 59 sqlDataRead.Close(); 60 sqlDataRead.Dispose(); 61 } 62 63 64 } 65 Application.DoEvents(); 66 } 67 } 68 69 70 singleThreadWatch.Stop(); 71 72 TimeSpan ts = singleThreadWatch.Elapsed; 73 74 label1.Text = "单线程 表数量：" + list.Length.ToString() + " 总用时间: " + ts.TotalMilliseconds.ToString(); 75 76 77 } 78 }
2 使用线程池读取代码：
private void button3_Click(object sender, EventArgs e) { if (listBox1.Items.Count > 0) { tableCount = 0; useTime = 0; label1.Text = ""; tabControl1.Controls.Clear(); string[] list = new string[listBox1.Items.Count]; for (int i = 0; i < listBox1.Items.Count; i++) { list[i] = listBox1.Items[i].ToString(); } ThreadSart(list); } } private void ThreadSart(object t) { string[] objs = t as string[]; if (objs != null && objs.Length > 0) { foreach (string item in objs) { tableCount += 1; ThreadPool.QueueUserWorkItem(new WaitCallback(OpenAllTables), item); Application.DoEvents(); } } } public void OpenAllTables(object obj) { OpenDBTables(obj.ToString()); } private void OpenDBTables(string b) { System.Diagnostics.Stopwatch stopWatch = new System.Diagnostics.Stopwatch(); stopWatch.Start(); using (SqlConnection con = new SqlConnection(connectionString)) { if (con.State != ConnectionState.Open) con.Open(); string selectAllTableNameSQL = "select * from [" + b.ToString()+"]"; using (SqlCommand sqlCmd = new SqlCommand(selectAllTableNameSQL, con)) { sqlCmd.CommandType = CommandType.Text; SqlDataReader sqlDataRead = sqlCmd.ExecuteReader(); if (null != sqlDataRead) { DataTable dt = new DataTable(); dt.Load(sqlDataRead); if (null != dt && dt.Rows.Count > 0) { setData(dt,b); } } sqlDataRead.Close(); sqlDataRead.Dispose(); } } stopWatch.Stop(); TimeSpan ts = stopWatch.Elapsed; Write(b.ToString() + " 打开用时：" + ts.TotalMilliseconds.ToString()); useTime += ts.TotalMilliseconds; ShowCountAndTime(); Application.DoEvents(); //int MaxWorkerThreads, miot, AvailableWorkerThreads, aiot; ////获得最大的线程数量 //ThreadPool.GetMaxThreads(out MaxWorkerThreads, out miot); //AvailableWorkerThreads = aiot = 0; ////获得可用的线程数量 //ThreadPool.GetAvailableThreads(out AvailableWorkerThreads, out aiot); ////返回线程池中活动的线程数 //Write("活动的线程数:" + (MaxWorkerThreads - AvailableWorkerThreads).ToString()); }
