本文介绍了多线程处理主线程，按顺序进行.的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！
问题描述
我在挂断主线程的多线程ping时遇到问题.调试问题时，我注意到当主线程挂起时，它正在启动每个线程并移至下一个ping.基本上，它必须ping 5个不同的IP地址，如果它们都掉了，我的整个线程都会挂断20-30秒.我正在使用BeginInvoke，但它似乎仍然无法正常工作.
另一个奇怪的是，我在每个线程的末尾添加了一个消息框，以查看它们的完成情况.我有5个线程，每个线程的末尾都有一个消息框，弹出并显示完成".好吧，它不是弹出仅5次，而是运行10次，就好像它在运行两次一样.通常我在这些线程中没有消息框，只是在那里我可以尝试找出正在发生的事情，但是我很困惑.
这将获取IP地址并启动线程:
Private Sub PingThreadStart()
Host = zeroStoreNum
IP = "10."
Select Case (Host.Substring(0, 1))
Case "0"
IP = IP & "10."
Case "1"
IP = IP & "11."
Case "2"
IP = IP & "12."
Case "3"
IP = IP & "13."
Case "4"
IP = IP & "14."
Case "5"
IP = IP & "15."
Case "6"
IP = IP & "16."
Case "7"
IP = IP & "17."
Case "8"
IP = IP & "18."
Case "9"
IP = IP & "19."
End Select
Select Case (Host.Substring(1, 1))
Case "0"
'IP = IP & "0"
Case "1"
IP = IP & "1"
Case "2"
IP = IP & "2"
Case "3"
IP = IP & "3"
Case "4"
IP = IP & "4"
Case "5"
IP = IP & "5"
Case "6"
IP = IP & "6"
Case "7"
IP = IP & "7"
Case "8"
IP = IP & "8"
Case "9"
IP = IP & "9"
End Select
Select Case (Host.Substring(2, 1))
Case "0"
IP = IP & "0."
Case "1"
IP = IP & "1."
Case "2"
IP = IP & "2."
Case "3"
IP = IP & "3."
Case "4"
IP = IP & "4."
Case "5"
IP = IP & "5."
Case "6"
IP = IP & "6."
Case "7"
IP = IP & "7."
Case "8"
IP = IP & "8."
Case "9"
IP = IP & "9."
End Select
If Host = 100 Then
IP = "10.10.100."
End If
If Host = 200 Then
IP = "10.11.100."
End If
If Host = 300 Then
IP = "10.12.100."
End If
If Host = 400 Then
IP = "10.13.100."
End If
If Host = 500 Then
IP = "10.14.100."
End If
If Host = 600 Then
IP = "10.15.100."
End If
If Host = 700 Then
IP = "10.16.100."
End If
If Host = 800 Then
IP = "10.17.100."
End If
If Host = 900 Then
IP = "10.18.100."
End If
lblIPschemeCH.Text = IP & "X"
SonicWALL = IP & "1"
primary = IP & "2"
secondary = IP & "3"
Dim PingPublicTry As Thread = New Thread(AddressOf PingPublicTH)
Dim PingSWpublicTry As Thread = New Thread(AddressOf PingSWpublicTH)
Dim PingDotOneTry As Thread = New Thread(AddressOf PingDotOneTH)
Dim PingDotTwoTry As Thread = New Thread(AddressOf PingDotTwoTH)
Dim PingDotThreeTry As Thread = New Thread(AddressOf PingDotThreeTH)
PingPublicTry.IsBackground = True
PingSWpublicTry.IsBackground = True
PingDotOneTry.IsBackground = True
PingDotTwoTry.IsBackground = True
PingDotThreeTry.IsBackground = True
If ModemPublic = "DHCP" Or SonicWALLPublic = "DHCP" Then
PingDotOneTry.Start()
PingDotTwoTry.Start()
PingDotThreeTry.Start()
Else
PingPublicTry.Start()
PingSWpublicTry.Start()
PingDotOneTry.Start()
PingDotTwoTry.Start()
PingDotThreeTry.Start()
End If
End Sub
这是我的脚步:
Private Sub PingPublicTH()
Dim pingactmodem As New System.Net.NetworkInformation.Ping
Dim pingretmodem As System.Net.NetworkInformation.PingReply
Dim speedmodem As Integer
Try
pingretmodem = pingactmodem.Send(ModemPublic)
speedmodem = pingretmodem.RoundtripTime
Catch ex As Exception
End Try
If (lblModCh.InvokeRequired) Then
Dim show As New PingPublicDel(AddressOf PingPublicTH)
Me.lblModCh.BeginInvoke(show)
Else
If speedmodem >= 1 And speedmodem <= 500 Then
lblModCh.BackColor = Color.Green
ElseIf speedmodem >= 501 And speedmodem <= 1500 Then
lblModCh.BackColor = Color.Orange
ElseIf speedmodem >= 1501 Then
lblModCh.BackColor = Color.Red
ElseIf speedmodem = 0 Then
lblModCh.BackColor = Color.Black
End If
End If
MessageBox.Show("Done modem")
End Sub
Private Sub PingSWpublicTH()
Dim pingactswp As New System.Net.NetworkInformation.Ping
Dim pingretswp As System.Net.NetworkInformation.PingReply
Dim speedswp As Integer
Try
pingretswp = pingactswp.Send(SonicWALLPublic)
speedswp = pingretswp.RoundtripTime
Catch ex As Exception
End Try
If (lbSWPCh.InvokeRequired) Then
Dim show As New PingSwPublicDel(AddressOf PingSWpublicTH)
Me.lbSWPCh.BeginInvoke(show)
Else
If speedswp >= 1 And speedswp <= 500 Then
lbSWPCh.BackColor = Color.Green
ElseIf speedswp >= 501 And speedswp <= 1500 Then
lbSWPCh.BackColor = Color.Orange
ElseIf speedswp >= 1501 Then
lbSWPCh.BackColor = Color.Red
ElseIf speedswp = 0 Then
lbSWPCh.BackColor = Color.Black
End If
End If
MessageBox.Show("Done swp")
End Sub
Private Sub PingDotOneTH()
Dim pingact1 As New System.Net.NetworkInformation.Ping
Dim pingret1 As System.Net.NetworkInformation.PingReply
Dim speed1 As Integer
pingret1 = pingact1.Send(SonicWALL)
speed1 = pingret1.RoundtripTime
If (lblSWch.InvokeRequired) Then
Dim show As New PingDotOneDel(AddressOf PingDotOneTH)
Me.lblSWch.BeginInvoke(show)
Else
If speed1 >= 1 And speed1 <= 500 Then
lblSWch.Text = (speed1)
lblSWch.BackColor = Color.Green
ElseIf speed1 >= 501 And speed1 <= 1500 Then
lblSWch.Text = (speed1)
lblSWch.BackColor = Color.Orange
ElseIf speed1 >= 1501 Then
lblSWch.Text = (speed1)
lblSWch.BackColor = Color.Red
ElseIf speed1 = 0 Then
lblSWch.Text = "Down"
lblSWch.BackColor = Color.Black
End If
End If
MessageBox.Show("Done .1")
End Sub
Private Sub PingDotTwoTH()
Dim pingact2 As New System.Net.NetworkInformation.Ping
Dim pingret2 As System.Net.NetworkInformation.PingReply
Dim Speed2 As Integer
pingret2 = pingact2.Send(primary)
Speed2 = pingret2.RoundtripTime
If (lblMainpcCH.InvokeRequired) Then
Dim show As New PingDotTwoDel(AddressOf PingDotTwoTH)
Me.lblMainpcCH.BeginInvoke(show)
Else
If Speed2 >= 1 And Speed2 <= 500 Then
lblMainpcCH.Text = (Speed2)
lblMainpcCH.BackColor = Color.Green
ElseIf Speed2 >= 501 And Speed2 <= 1500 Then
lblMainpcCH.Text = (Speed2)
lblMainpcCH.BackColor = Color.Orange
ElseIf Speed2 >= 1501 Then
lblMainpcCH.Text = (Speed2)
lblMainpcCH.BackColor = Color.Red
ElseIf Speed2 = 0 Then
lblMainpcCH.Text = "Down"
lblMainpcCH.BackColor = Color.Black
End If
End If
MessageBox.Show("Done .2")
End Sub
Private Sub PingDotThreeTH()
Dim pingact3 As New System.Net.NetworkInformation.Ping
Dim pingret3 As System.Net.NetworkInformation.PingReply
Dim speed3 As Integer
pingret3 = pingact3.Send(secondary)
speed3 = pingret3.RoundtripTime
If (lblSecondch.InvokeRequired) Then
Dim show As New PingDotThreeDel(AddressOf PingDotThreeTH)
Me.lblSecondch.BeginInvoke(show)
Else
If speed3 >= 1 And speed3 <= 500 Then
lblSecondch.Text = (speed3)
lblSecondch.BackColor = Color.Green
ElseIf speed3 >= 501 And speed3 <= 1500 Then
lblSecondch.Text = (speed3)
lblSecondch.BackColor = Color.Orange
ElseIf speed3 >= 1501 Then
lblSecondch.Text = (speed3)
lblSecondch.BackColor = Color.Red
ElseIf speed3 = 0 Then
lblSecondch.Text = "Down"
lblSecondch.BackColor = Color.Black
End If
End If
MessageBox.Show("Done .3")
End Sub
解决方案
这里的问题是您再次调用相同的方法，这些方法应该在线程中运行.这将导致再次发送ping请求，但是这次代码在UI线程上运行(因此冻结).您应该确保仅调用更新UI的代码.
这是可选的，但我建议您使用 扩展名方法 为您执行调用检查，因为它可以提高可读性，但同时也减少了您必须编写的代码量:
Imports System.Runtime.CompilerServices
Public Module Extensions
<Extension()> _
Public Sub InvokeIfRequired(ByVal Control As Control, ByVal Method As [Delegate], ByVal ParamArray Parameters As Object())
If Parameters Is Nothing OrElse _
Parameters.Length = 0 Then Parameters = Nothing 'If Parameters is null or has a length of zero then no parameters should be passed.
If Control.InvokeRequired = True Then
Control.Invoke(Method, Parameters)
Else
Method.DynamicInvoke(Parameters)
End If
End Sub
End Module
现在，如果您以 .NET Framework 4.0 (或更高版本)为目标，则可以使用 lambda表达式 以获得快速的内联委托:
Me.InvokeIfRequired( _
Sub()
If speedmodem >= 1 AndAlso speedmodem <= 500 Then
lblModCh.BackColor = Color.Green
ElseIf speedmodem >= 501 And speedmodem <= 1500 Then
lblModCh.BackColor = Color.Orange
ElseIf speedmodem >= 1501 Then
lblModCh.BackColor = Color.Red
ElseIf speedmodem = 0 Then
lblModCh.BackColor = Color.Black
End If
End Sub)
但是，如果您定位 .NET Framework 3.5 或更低版本，则必须以常规方式创建委托:
Private Delegate Sub UpdatePingStatusDelegate(ByVal speedmodem As Integer)
Private Sub PingPublicTH()
...your code...
Me.InvokeIfRequired(New UpdatePingStatusDelegate(AddressOf UpdateStatusPublicTH), speedmodem)
End Sub
Private Sub UpdateStatusPublicTH(ByVal speedmodem As Integer)
If speedmodem >= 1 AndAlso speedmodem <= 500 Then
lblModCh.BackColor = Color.Green
ElseIf speedmodem >= 501 And speedmodem <= 1500 Then
lblModCh.BackColor = Color.Orange
ElseIf speedmodem >= 1501 Then
lblModCh.BackColor = Color.Red
ElseIf speedmodem = 0 Then
lblModCh.BackColor = Color.Black
End If
End Sub
注意:
-
使用扩展方法
InvokeIfRequired时，无需在其余代码中检查Control.InvokeRequired.您只需对扩展方法进行一次调用，它将为您进行检查. -
如果您使用我的第二种方法，则只需一个
UpdatePingStatusDelegate委托(如果您需要的只是一个整数即可更新所有线程的状态).
另请参阅 And和AndAlso 之间的区别. >
I'm having an issue with multithreading pings that are hanging up my main thread. When debugging the issue, I notice that while the main thread is hung up, it is starting each thread and moving to the next for the pings. Basically it has to ping 5 different IP addresses, and if they're all down my whole thread hangs up for 20 - 30 seconds. I'm using the BeginInvoke, but it still doesn't seem to work right.
Another oddity is that I added a message box at the end of each thread, just to see how they're completing. I have 5 threads and at the end of each is a message box that pops up and says "Done." Well, instead of popping up just 5 times, it's coming up 10 times as if it's running twice. Normally I don't have message boxes in these threads, it is just there for me to try and figure out what is going on, but I'm stumped.
This gets the IP addresses and starts the threads:
Private Sub PingThreadStart()
Host = zeroStoreNum
IP = "10."
Select Case (Host.Substring(0, 1))
Case "0"
IP = IP & "10."
Case "1"
IP = IP & "11."
Case "2"
IP = IP & "12."
Case "3"
IP = IP & "13."
Case "4"
IP = IP & "14."
Case "5"
IP = IP & "15."
Case "6"
IP = IP & "16."
Case "7"
IP = IP & "17."
Case "8"
IP = IP & "18."
Case "9"
IP = IP & "19."
End Select
Select Case (Host.Substring(1, 1))
Case "0"
'IP = IP & "0"
Case "1"
IP = IP & "1"
Case "2"
IP = IP & "2"
Case "3"
IP = IP & "3"
Case "4"
IP = IP & "4"
Case "5"
IP = IP & "5"
Case "6"
IP = IP & "6"
Case "7"
IP = IP & "7"
Case "8"
IP = IP & "8"
Case "9"
IP = IP & "9"
End Select
Select Case (Host.Substring(2, 1))
Case "0"
IP = IP & "0."
Case "1"
IP = IP & "1."
Case "2"
IP = IP & "2."
Case "3"
IP = IP & "3."
Case "4"
IP = IP & "4."
Case "5"
IP = IP & "5."
Case "6"
IP = IP & "6."
Case "7"
IP = IP & "7."
Case "8"
IP = IP & "8."
Case "9"
IP = IP & "9."
End Select
If Host = 100 Then
IP = "10.10.100."
End If
If Host = 200 Then
IP = "10.11.100."
End If
If Host = 300 Then
IP = "10.12.100."
End If
If Host = 400 Then
IP = "10.13.100."
End If
If Host = 500 Then
IP = "10.14.100."
End If
If Host = 600 Then
IP = "10.15.100."
End If
If Host = 700 Then
IP = "10.16.100."
End If
If Host = 800 Then
IP = "10.17.100."
End If
If Host = 900 Then
IP = "10.18.100."
End If
lblIPschemeCH.Text = IP & "X"
SonicWALL = IP & "1"
primary = IP & "2"
secondary = IP & "3"
Dim PingPublicTry As Thread = New Thread(AddressOf PingPublicTH)
Dim PingSWpublicTry As Thread = New Thread(AddressOf PingSWpublicTH)
Dim PingDotOneTry As Thread = New Thread(AddressOf PingDotOneTH)
Dim PingDotTwoTry As Thread = New Thread(AddressOf PingDotTwoTH)
Dim PingDotThreeTry As Thread = New Thread(AddressOf PingDotThreeTH)
PingPublicTry.IsBackground = True
PingSWpublicTry.IsBackground = True
PingDotOneTry.IsBackground = True
PingDotTwoTry.IsBackground = True
PingDotThreeTry.IsBackground = True
If ModemPublic = "DHCP" Or SonicWALLPublic = "DHCP" Then
PingDotOneTry.Start()
PingDotTwoTry.Start()
PingDotThreeTry.Start()
Else
PingPublicTry.Start()
PingSWpublicTry.Start()
PingDotOneTry.Start()
PingDotTwoTry.Start()
PingDotThreeTry.Start()
End If
End Sub
And this is my treads:
Private Sub PingPublicTH()
Dim pingactmodem As New System.Net.NetworkInformation.Ping
Dim pingretmodem As System.Net.NetworkInformation.PingReply
Dim speedmodem As Integer
Try
pingretmodem = pingactmodem.Send(ModemPublic)
speedmodem = pingretmodem.RoundtripTime
Catch ex As Exception
End Try
If (lblModCh.InvokeRequired) Then
Dim show As New PingPublicDel(AddressOf PingPublicTH)
Me.lblModCh.BeginInvoke(show)
Else
If speedmodem >= 1 And speedmodem <= 500 Then
lblModCh.BackColor = Color.Green
ElseIf speedmodem >= 501 And speedmodem <= 1500 Then
lblModCh.BackColor = Color.Orange
ElseIf speedmodem >= 1501 Then
lblModCh.BackColor = Color.Red
ElseIf speedmodem = 0 Then
lblModCh.BackColor = Color.Black
End If
End If
MessageBox.Show("Done modem")
End Sub
Private Sub PingSWpublicTH()
Dim pingactswp As New System.Net.NetworkInformation.Ping
Dim pingretswp As System.Net.NetworkInformation.PingReply
Dim speedswp As Integer
Try
pingretswp = pingactswp.Send(SonicWALLPublic)
speedswp = pingretswp.RoundtripTime
Catch ex As Exception
End Try
If (lbSWPCh.InvokeRequired) Then
Dim show As New PingSwPublicDel(AddressOf PingSWpublicTH)
Me.lbSWPCh.BeginInvoke(show)
Else
If speedswp >= 1 And speedswp <= 500 Then
lbSWPCh.BackColor = Color.Green
ElseIf speedswp >= 501 And speedswp <= 1500 Then
lbSWPCh.BackColor = Color.Orange
ElseIf speedswp >= 1501 Then
lbSWPCh.BackColor = Color.Red
ElseIf speedswp = 0 Then
lbSWPCh.BackColor = Color.Black
End If
End If
MessageBox.Show("Done swp")
End Sub
Private Sub PingDotOneTH()
Dim pingact1 As New System.Net.NetworkInformation.Ping
Dim pingret1 As System.Net.NetworkInformation.PingReply
Dim speed1 As Integer
pingret1 = pingact1.Send(SonicWALL)
speed1 = pingret1.RoundtripTime
If (lblSWch.InvokeRequired) Then
Dim show As New PingDotOneDel(AddressOf PingDotOneTH)
Me.lblSWch.BeginInvoke(show)
Else
If speed1 >= 1 And speed1 <= 500 Then
lblSWch.Text = (speed1)
lblSWch.BackColor = Color.Green
ElseIf speed1 >= 501 And speed1 <= 1500 Then
lblSWch.Text = (speed1)
lblSWch.BackColor = Color.Orange
ElseIf speed1 >= 1501 Then
lblSWch.Text = (speed1)
lblSWch.BackColor = Color.Red
ElseIf speed1 = 0 Then
lblSWch.Text = "Down"
lblSWch.BackColor = Color.Black
End If
End If
MessageBox.Show("Done .1")
End Sub
Private Sub PingDotTwoTH()
Dim pingact2 As New System.Net.NetworkInformation.Ping
Dim pingret2 As System.Net.NetworkInformation.PingReply
Dim Speed2 As Integer
pingret2 = pingact2.Send(primary)
Speed2 = pingret2.RoundtripTime
If (lblMainpcCH.InvokeRequired) Then
Dim show As New PingDotTwoDel(AddressOf PingDotTwoTH)
Me.lblMainpcCH.BeginInvoke(show)
Else
If Speed2 >= 1 And Speed2 <= 500 Then
lblMainpcCH.Text = (Speed2)
lblMainpcCH.BackColor = Color.Green
ElseIf Speed2 >= 501 And Speed2 <= 1500 Then
lblMainpcCH.Text = (Speed2)
lblMainpcCH.BackColor = Color.Orange
ElseIf Speed2 >= 1501 Then
lblMainpcCH.Text = (Speed2)
lblMainpcCH.BackColor = Color.Red
ElseIf Speed2 = 0 Then
lblMainpcCH.Text = "Down"
lblMainpcCH.BackColor = Color.Black
End If
End If
MessageBox.Show("Done .2")
End Sub
Private Sub PingDotThreeTH()
Dim pingact3 As New System.Net.NetworkInformation.Ping
Dim pingret3 As System.Net.NetworkInformation.PingReply
Dim speed3 As Integer
pingret3 = pingact3.Send(secondary)
speed3 = pingret3.RoundtripTime
If (lblSecondch.InvokeRequired) Then
Dim show As New PingDotThreeDel(AddressOf PingDotThreeTH)
Me.lblSecondch.BeginInvoke(show)
Else
If speed3 >= 1 And speed3 <= 500 Then
lblSecondch.Text = (speed3)
lblSecondch.BackColor = Color.Green
ElseIf speed3 >= 501 And speed3 <= 1500 Then
lblSecondch.Text = (speed3)
lblSecondch.BackColor = Color.Orange
ElseIf speed3 >= 1501 Then
lblSecondch.Text = (speed3)
lblSecondch.BackColor = Color.Red
ElseIf speed3 = 0 Then
lblSecondch.Text = "Down"
lblSecondch.BackColor = Color.Black
End If
End If
MessageBox.Show("Done .3")
End Sub
解决方案
The problem here is that you invoke the same methods once again, which are supposed to be run in threads. This causes the ping request to be sent yet another time, but this time the code runs on the UI thread (hence why it freezes). You should make sure to only invoke the code that updates the UI.
This is optional, but I recommend you to use an extension method to do the invocation check for you since it will improve readability but also decrease the amount of code you have to write:
Imports System.Runtime.CompilerServices
Public Module Extensions
<Extension()> _
Public Sub InvokeIfRequired(ByVal Control As Control, ByVal Method As [Delegate], ByVal ParamArray Parameters As Object())
If Parameters Is Nothing OrElse _
Parameters.Length = 0 Then Parameters = Nothing 'If Parameters is null or has a length of zero then no parameters should be passed.
If Control.InvokeRequired = True Then
Control.Invoke(Method, Parameters)
Else
Method.DynamicInvoke(Parameters)
End If
End Sub
End Module
Now, if you target .NET Framework 4.0 (or higher) you can use a lambda expression for a quick, inline delegate:
Me.InvokeIfRequired( _
Sub()
If speedmodem >= 1 AndAlso speedmodem <= 500 Then
lblModCh.BackColor = Color.Green
ElseIf speedmodem >= 501 And speedmodem <= 1500 Then
lblModCh.BackColor = Color.Orange
ElseIf speedmodem >= 1501 Then
lblModCh.BackColor = Color.Red
ElseIf speedmodem = 0 Then
lblModCh.BackColor = Color.Black
End If
End Sub)
However if you target .NET Framework 3.5 or lower you have to create delegates the normal way:
Private Delegate Sub UpdatePingStatusDelegate(ByVal speedmodem As Integer)
Private Sub PingPublicTH()
...your code...
Me.InvokeIfRequired(New UpdatePingStatusDelegate(AddressOf UpdateStatusPublicTH), speedmodem)
End Sub
Private Sub UpdateStatusPublicTH(ByVal speedmodem As Integer)
If speedmodem >= 1 AndAlso speedmodem <= 500 Then
lblModCh.BackColor = Color.Green
ElseIf speedmodem >= 501 And speedmodem <= 1500 Then
lblModCh.BackColor = Color.Orange
ElseIf speedmodem >= 1501 Then
lblModCh.BackColor = Color.Red
ElseIf speedmodem = 0 Then
lblModCh.BackColor = Color.Black
End If
End Sub
Note:
When using the extension method
InvokeIfRequiredyou don't need to checkControl.InvokeRequiredin the rest of your code. You only require the one call to the extension method and it will do the checking for you.If you use my second method you only need the one
UpdatePingStatusDelegatedelegate if all you need is one integer to update the status from all the threads.
Please also see the difference between And and AndAlso.
这篇关于多线程处理主线程，按顺序进行.的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持！