frmdeadlock.vb

来自「Microsoft Mobile Development Handbook的代码」· VB 代码 · 共 61 行

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