VB.NET并行与分布式编程(6)-线程与内核同步[4]

我们下面通过WaitHandle.WaitOne 方法和EventWaitHandle.Set 方法来实现

Imports SystemImports System.ThreadingImports System.DiagnosticsImports System.Diagnostics.ThreadStateModule Module1 Sub Main() Dim mythread1 As Thread Dim mythread2 As Thread Dim mythread3 As Thread '创建线程对象 mythread1 = New Thread(AddressOf mythreadrun) mythread2 = New Thread(AddressOf mythreadrun) mythread3 = New Thread(AddressOf mythreadrun) mythread1.Name = "thread_1" mythread2.Name = "thread_2" mythread3.Name = "thread_3" Console.WriteLine(Now.ToLongTimeString & "线程对象创建完毕,开始执行线程") Dim myprocess As Process = Process.GetCurrentProcess() Console.WriteLine("进程名称:" & myprocess.ProcessName) '执行线程 mythread1.Start(myprocess) mythread2.Start(myprocess) mythread3.Start(myprocess) '等待线程完成 mythread1.Join() mythread2.Join() mythread3.Join() '线程执行完毕 Console.WriteLine(Now.ToLongTimeString & "线程执行完毕!") End Sub Public Sub mythreadrun(ByVal myprocess As Object) Dim mynum As Double Static Dim jg As Double = 100 Static autoEvent As New AutoResetEvent(True) Try For mynum = 1 To 2 Step 0.1 autoEvent.WaitOne() 'autoEvent.Reset() jg -= mynum Console.WriteLine(Thread.CurrentThread.Name & "==>" & Now.ToLongTimeString & "=>" & (jg + mynum) & "-" & mynum & "，计算结果为：" & jg) autoEvent.Set() Next Catch Console.WriteLine(Thread.CurrentThread.Name & " " & Now.ToLongTimeString & "线程异常终止!") '终止线程 Thread.CurrentThread.Abort() Finally Console.WriteLine(Thread.CurrentThread.Name & "优先级: " & Thread.CurrentThread.Priority.ToString) Console.WriteLine(Thread.CurrentThread.Name & " " & Now.ToLongTimeString & "线程运行完毕!") End Try End SubEnd Module

??注意这部分代码

??????????????? autoEvent.WaitOne()
??????????????? 'autoEvent.Reset()
??????????????? jg -= mynum
??????????????? Console.WriteLine(Thread.CurrentThread.Name & "==>" & Now.ToLongTimeString & "=>" & (jg + mynum) & "-" & mynum & "，计算结果为：" & jg)
??????????????? autoEvent.Set()
?为什么将autoEvent.Reset()注释，因为当线程等待到资源后，即当前 WaitHandle 收到信号后，会自动将状态置为非终止

运行效果如下:

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从上图可以看出，我们用多个线程完成对某个数的减法运算真正成功了，而且解决了同步问题

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