Question

I created a VB.Net application that will read from excel file and put the data into a table.
I used an excel sheet which has 3 columns and 65000 rows.
Before starts reading the excel my machine’s CPU Usage is around 15%, but during reading the CPU Usage jumps upto 95%.
I don’t know why it is happening? Can someone help me in this issue?
The following is the code i’d written:

Private Sub readFromExcel(ByVal fileName As String, ByVal sheetName As String)
    Dim connString As String = "data source=XE; user=test; password=test"
    Dim con As New OracleConnection(connString)
    Dim str1 As String
    Dim str2 As String
    Dim str3 As String
    Dim xlApp As Excel.Application
    Dim xlWorkBook As Excel.Workbook
    Dim xlWorkSheet As Excel.Worksheet
    xlApp = New Excel.ApplicationClass
    xlWorkBook = xlApp.Workbooks.Open(fileName)
    xlWorkSheet = xlWorkBook.Worksheets(sheetName)
    Dim x As Integer
    Dim y As Integer
    Dim i As Integer
    x = xlWorkSheet.Rows.Count()
    y = xlWorkSheet.Columns.Count()
    Try
        For i = 1 To x - 1
            'MsgBox(xlWorkSheet.Cells(i, 0).value)
            str1 = xlWorkSheet.Cells(i, 1).value
            str2 = xlWorkSheet.Cells(i, 2).value
            str3 = xlWorkSheet.Cells(i, 3).value
            insertData()
        Next
    Catch ex As Exception
        MsgBox(ex.Message())
    Finally
        con.Close()
        xlWorkBook.Close()
    End Try
End Sub

Private Sub insertData()
    Dim str As String
    str = "insert into test_import values('" + str1 + "'," + str2 + "," + str3 + ")"
    Dim cmd As New OracleCommand()
    cmd.CommandText = str
    cmd.Connection = con
    cmd.ExecuteNonQuery()
End Sub

thx in advance.

Answer 1

This is entirely normal. A program only doesn’t burn 100% core when it gets bogged down by I/O. Reading from a disk or network card, that blocks a program while the operating system supplies the data. Your code doesn’t bog down like that, you are asking it to do a bunch of work. Getting 195,000 cell values one by one just takes a while. Excel is an out-of-process COM server so every cell read requires two CPU context switches. You can optimize it a bit by using a Range instead. Or by running it on a machine with a two-core CPU so it only shoots up to 50%.

Feature, not a bug.