vb.net - 将行添加到数据源后，当垂直滚动条出现在数据绑定数据网格视图中时程序挂起

Question

由于我没有正确提出问题，因此重新发布。
用 VB.NET 4.6 编写的是我的 POS Scan 项目。
它旨在通过 com 端口处理来自扫描仪的扫描。
当扫描某些东西时，事件处理程序（subSerialDataHandler）会调用 subHandleScan，它会根据大小写决定如何处理扫描。
扫描将显示在 dgBarcodes 中。
您还可以通过 btnManuallyAdd 手动将项目添加到 dgBarcodes 的数据源 (dtBarcodes)，这将调用相同的 subHandleScan。

现在这是我正在努力解决的问题；
当扫描足够多的项目以使滚动条需要出现在 datagridview 中时，程序会挂起。
通过按钮手动添加项目时，即使需要出现滚动条，程序也不会挂起。
扫描足够少的项目以使滚动条不需要出现，程序不会挂起。
什么可能导致这种情况，我需要做些什么来防止程序挂起？

这是代码

     Imports System.IO.Ports
     Imports System.Configuration
     Imports System.Threading
    Imports System.Threading.Tasks
     Imports System.Text.RegularExpressions
     Imports Microsoft.Web.WebView2.Core
     Imports POS_Scan.clsUtilities
     
     Public Class frmPractice
         Public Shared frmRefund As New frmRefund 'create an instance of the form
         Public Shared frmExchangeIn As New frmExchangeIn 'create an instance of the form
         Public Shared frmExchangeOut As New frmExchangeOut 'create an instance of the form
         Public Delegate Sub dlgRefund(strBarcode As String) 'Delegates for other form access
         Public Delegate Sub dlgExchangeIn(strBarcode As String) 'Delegates for other form access
         Public Delegate Sub dlgExchangeOut(strBarcode As String) 'Delegates for other form access
         Dim mySerialPort() As SerialPort
         Dim dtBarcodes As New DataTable
         Public Shared strAction As String = "Sale" 'Semaphore to dictate how to process a barcode scan event.
     
         Private Sub frmPractice_Load(sender As Object, e As EventArgs) Handles MyBase.Load
             dtBarcodes.Columns.Add("dScan", Type.GetType("System.String")) 'create a column with a string input
             dtBarcodes.Columns.Add("strBarcode", Type.GetType("System.String")) 'create a column with a string input
             dtBarcodes.Columns.Add("strMethod", Type.GetType("System.String")) 'create a column with a string input
             dtBarcodes.Columns.Add("strAmount", Type.GetType("System.String")) 'create a column with a string input
     
             subSerialListener()
     
             dgBarcodes.DataSource = dtBarcodes.DefaultView 'bind it
         End Sub
     
         Private Sub subSerialListener()
             Dim strPorts() As String
             strPorts = fnGetSerialPorts() 'get all serial ports of this computer
     
             Dim intNumberOfPorts As Integer = strPorts.Count - 1
             ReDim mySerialPort(intNumberOfPorts) 'create a 0 based array of serial ports with the right size
             For i = 0 To intNumberOfPorts
                 mySerialPort(i) = New SerialPort(strPorts(i))
                 mySerialPort(i).BaudRate = 9600
                 mySerialPort(i).Parity = Parity.None
                 mySerialPort(i).StopBits = StopBits.One
                 mySerialPort(i).DataBits = 8
                 mySerialPort(i).Handshake = Handshake.None
                 mySerialPort(i).RtsEnable = True
     
                 AddHandler mySerialPort(i).DataReceived, AddressOf subSerialDataHandler
                 mySerialPort(i).Open()
                 'mySerialPort(i).Close()
             Next i
         End Sub
     
         Private Function fnGetSerialPorts() As String()
             Dim strPorts As String() = SerialPort.GetPortNames() 'get an array of port names of this computer
             Return strPorts
         End Function
     
         Private Sub subSerialDataHandler(sender As Object, e As SerialDataReceivedEventArgs)
             Dim sp As SerialPort = CType(sender, SerialPort) 'convert the sender into a serialport
             Dim strInData As String = sp.ReadExisting() 'take the data in the serialport and put it in a string
             subHandleScan(DateTime.Now.ToString("yyyy/MM/dd HH:mm:ss.ff"), strInData, "Scan") 'pass it to the scan
         End Sub
     
         Private Sub subHandleScan(strDScan As String, strBarcode As String, strMethod As String)
             Dim strNow As String = DateTime.Now.ToString("yyyy/MM/dd HH:mm:ss")
             Select Case strAction
                 Case "Sale" 'if the scan was a sale
                     subWriteDebugLog(strNow, strMethod, strBarcode) 'write debuglog for a Sale scan
                     Dim row1 As DataRow = dtBarcodes.NewRow() 'make a new row
                     row1("dScan") = strDScan 'set the date
                     row1("strBarcode") = strBarcode 'set the barcode
                     row1("strMethod") = strMethod 'set the method
                     dtBarcodes.Rows.Add(row1) 'add the row
     
                 Case "Refund" 'if the scan was a refund 
                     subWriteDebugLog(strNow, "RefundScan", strBarcode) 'write debuglog for a Refund scan
                     If frmRefund.txtReturnedBarcode.InvokeRequired Then 'Calling from another thread
                         Dim dlgRefund As New dlgRefund(AddressOf frmRefund.subScan) 'sets frmRefund.txtReturnedBarcode.Text =
 strBarcode
                         Me.Invoke(dlgRefund, strBarcode) 'Execute delegate in the UI thread, pass args as an array
                     End If
     
                 Case "ExchangeIn"
                     subWriteDebugLog(strNow, "ExchangeInScan", strBarcode) 'write debuglog for a ExchangeIn scan
                     If frmExchangeIn.txtReturnedBarcode.InvokeRequired Then 'Calling from another thread 
                         Dim dlgExchangeIn As New dlgExchangeIn(AddressOf frmExchangeIn.subScan) 'sets
 frmExchangeIn.txtReturnedBarcode.Text = strBarcode
                         Me.Invoke(dlgExchangeIn, strBarcode) 'Execute delegate in the UI thread, pass args as an array
                     End If
     
                 Case "ExchangeOut"
                     subWriteDebugLog(strNow, "ExchangeOutScan", strBarcode) 'write debuglog for a ExchangeOut scan
                     If frmExchangeOut.txtExchangedBarcode.InvokeRequired Then 'Calling from
 another thread
                         Dim dlgExhangeOut As New dlgExchangeOut(AddressOf frmExchangeOut.subScan) 'sets
 frmExchangeOut.txtExchangedBarcode.Text = strBarcode 
                         Me.Invoke(dlgExhangeOut, strBarcode) 'Execute delegate in the UI thread, pass args as an array
                     End If
             End Select
         End Sub
     
         Private Sub btnManuallyAdd_Click(sender As Object, e As EventArgs) Handles btnManuallyAdd.Click
             Dim strBarcode As String = Trim(txtManualBarcode.Text)
             If strBarcode <> "" Then 'if the clean string pulled from the textbox isn't empty
                 Dim dateTrans As DateTime = Now
                 subHandleScan(dateTrans.ToString("yyyy/MM/dd HH:mm:ss.ff"), strBarcode, "Manual") 'handle the scan
                 subWriteDebugLog(dateTrans.ToString("yyyy/MM/dd HH:mm:ss"), "btnManuallyAdd", strBarcode) 'write to the debug log
                 Me.txtManualBarcode.Text = "" 'clear the textbox
             End If
         End Sub



Private Sub btnExchange_Click(sender As Object, e As EventArgs) Handles btnExchange.Click
        frmExchangeIn.frmExchangeOut = frmExchangeOut 'pass the instance to the child
        strAction = "ExchangeIn" 'set the mode
        subWriteDebugLog(DateTime.Now.ToString("yyyy/MM/dd HH:mm:ss"), "btnExchange", "")  'write to the debug log
        frmExchangeIn.txtReturnedBarcode.Text = "" 'clear the control
        frmExchangeIn.ShowDialog(Me) 'show it
        If frmExchangeIn.DialogResult = Windows.Forms.DialogResult.OK Then 'if the child form saved something
            Dim strReturnedBarcode As String = frmExchangeIn.strReturnedBarcode 'get the barcode
            Dim strExchangedBarcode As String = frmExchangeIn.strExchangedBarcode 'get the barcode
            Dim row1 As DataRow = dtBarcodes.NewRow() 'make a new row
            Dim row2 As DataRow = dtBarcodes.NewRow() 'make a new row
            Dim dateNow As DateTime = DateTime.Now.ToString("yyyy/MM/dd HH:mm:ss.ff") 'grab the time so its the exact same for both rows
            'new item
            row1("dScan") = dateNow 'set the date
            row1("strBarcode") = strExchangedBarcode 'set the barcode
            row1("strMethod") = "-Exchange" 'set the method
            'Returned item
            row2("dScan") = dateNow 'set the date
            row2("strBarcode") = strReturnedBarcode 'set the barcode
            row2("strMethod") = "+Exchange" 'set the method
            dtBarcodes.Rows.Add(row1) 'add the row
            dtBarcodes.Rows.Add(row2) 'add the row
        End If
        strAction = "Sale" 'reset the mode
    End Sub

    Private Sub btnRefund_Click(sender As Object, e As EventArgs) Handles btnRefund.Click
        strAction = "Refund" 'set the mode
        subWriteDebugLog(DateTime.Now.ToString("yyyy/MM/dd HH:mm:ss"), "btnRefund", "")  'write to the debug log

        frmRefund.txtDate.Text = "" 'clear the control
        frmRefund.txtTime.Text = "" 'clear the control
        frmRefund.txtTotalValue.Text = "" 'clear the control
        frmRefund.txtReturnedBarcode.Text = "" 'clear the control
        frmRefund.txtReturnedValue.Text = "" 'clear the control
        frmRefund.ShowDialog(Me) 'show it
        If frmRefund.DialogResult = Windows.Forms.DialogResult.OK Then 'if the child form saved something
            Dim strReturnedBarcode As String = frmRefund.strReturnedBarcode 'get the barcode
            Dim decValue As Decimal = frmRefund.decValue 'get the value
            Dim row As DataRow = dtBarcodes.NewRow() 'make a new row
            row("dScan") = DateTime.Now.ToString("yyyy/MM/dd HH:mm:ss.ff") 'set the date
            row("strBarcode") = strReturnedBarcode 'set the barcode
            row("strMethod") = "Refund" 'set the method
            row("strAmount") = "-" & CStr(decValue) 'set the amount
            dtBarcodes.Rows.Add(row) 'add the row
        End If
        strAction = "Sale" 'reset the mode
    End Sub

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