VB.NET并行与分布式编程(六)-线程与内核同步[2]

VB.NET并行与分布式编程(6)-线程与内核同步[2]

那么我们通过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" '设置线程是否允许动态优先级 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 Try For mynum = 1 To 2 Step 0.1 Thread.BeginCriticalRegion() jg -= mynum Console.WriteLine(Thread.CurrentThread.Name & "==>" & Now.ToLongTimeString & "=>" & (jg + mynum) & "-" & mynum & "，计算结果为：" & jg) Thread.EndCriticalRegion() 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

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?其关健在于要解决对数据本身锁的问题，由此我们引入互斥体，互斥体是一个仅用于实现同步的内核对象，目的是构建拥有互斥行为的临界域(即前面所说的关键区域)

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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" '设置线程是否允许动态优先级 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 mymutex As New Mutex Static Dim jg As Double = 100 Try For mynum = 1 To 10 Thread.BeginCriticalRegion() mymutex.WaitOne() jg -= mynum Console.WriteLine(Thread.CurrentThread.Name & "==>" & Now.ToLongTimeString & "=>" & (jg + mynum) & "-" & mynum & "，计算结果为：" & jg) Thread.EndCriticalRegion() Thread.Sleep(0) mymutex.ReleaseMutex() Next Catch Console.WriteLine(Thread.CurrentThread.Name & " " & Now.ToLongTimeString & "线程异常终止!") '终止线程 Thread.CurrentThread.Abort() Finally 'mymutex.Close() 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

?上述代码的重点在于:

首先在工作线程中，声明一个静态互斥体，这样多个线程可以共享一个互斥体

??????? Static Dim mymutex As New Mutex

然后，通过??Mutex.WaitOne()方法等待互斥体被释放,使用完变量jg后，释放互斥体，允许其它线程对jg进行操作

??????? Try
??????????? For mynum = 1 To 10
??????????????? Thread.BeginCriticalRegion()
??????????????? mymutex.WaitOne()
??????????????? jg -= mynum
??????????????? Console.WriteLine(Thread.CurrentThread.Name & "==>" & Now.ToLongTimeString & "=>" & (jg + mynum) & "-" & mynum & "，计算结果为：" & jg)
??????????????? Thread.EndCriticalRegion()
??????????????? Thread.Sleep(0)
??????????????? mymutex.ReleaseMutex()

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可以看到通过引入互斥体，同步问题得到了解决

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