frmdeadlock.vb

清华大学出版社出版的 移动应用开发宝典 张大威（2008）的附书源代码

Imports Microsoft.VisualBasic
Imports System
Imports System.Windows.Forms
Imports System.Threading
Imports System.Diagnostics

Namespace CodeForChapter11cs
  Public Partial Class frmDeadlock
	  Inherits Form
	Public Sub New()
	  InitializeComponent()
	End Sub

	Private someLock As Object = New Object()
	Private someOtherLock As Object = New Object()

	Private Sub menuItem1_Click(ByVal sender As Object, ByVal e As EventArgs) Handles menuItem1.Click
	  Dim t1 As Thread = New Thread(AddressOf Me.DeadlockOne)
	  t1.Name = "Worker Thread 1 "
      't1.IsBackground = true
	  Dim t2 As Thread = New Thread(AddressOf Me.DeadlockTwo)
	  t2.Name = "Worker Thread 2 "
      't2.IsBackground = true

	  t1.Start()
	  t2.Start()
	End Sub

	Private Sub DeadlockOne()
	  Debug.WriteLine(Thread.CurrentThread.Name & " enters DeadLockOne")
	  SyncLock someLock
		Debug.WriteLine(Thread.CurrentThread.Name & " obtained SomeLock")
		' run some code
		Thread.Sleep(1) 'simulate a context switch
		SyncLock someOtherLock
		  Debug.WriteLine(Thread.CurrentThread.Name & " obtained SomeOtherLock")
		  'run some more code
		End SyncLock
	  End SyncLock
	  MessageBox.Show("Thread 1 done")
	End Sub

	Private Sub DeadlockTwo()
	  Debug.WriteLine(Thread.CurrentThread.Name & " enters DeadLockTwo")
	  SyncLock someOtherLock
		Debug.WriteLine(Thread.CurrentThread.Name & " obtained SomeOtherLock")
		' run some code
		Me.AnotherDemoMethod()
	  End SyncLock
	  MessageBox.Show("Thread 2 done")
	End Sub

	Private Sub AnotherDemoMethod()
	  Debug.WriteLine(Thread.CurrentThread.Name & " enters AnotherDemoMethod")
	  SyncLock someLock
		Debug.WriteLine(Thread.CurrentThread.Name & " obtained SomeLock")
		'run some more code
	  End SyncLock
	End Sub
  End Class
End Namespace