filestream锁住文件无法读取？

[kukumaiwu]

用filestream写的一个生成文件的方法
该方法被循环调用
偶尔会出现文件正在使用中的错误提示（很少出现）
跟踪后发现停在new filestream这一句
用gc.collect都不行
请问是什么原因？

Public Function outputFile(ByVal strFilePath As String, ByVal str As String) As Boolean
        Dim strPath As String = strFilePath
        Dim strmFile As Stream
        Dim ecdgSJIS As System.Text.Encoding = System.Text.Encoding.GetEncoding("shift_jis")
        Dim strmwriWriter As StreamWriter
        Dim intByteCnt As Integer = 0
        Dim strMsg As String
        Dim strFile As String = ""
        Dim intCnt As Integer
        Try
            strmFile = New FileStream(strPath, FileMode.OpenOrCreate, FileAccess.Read, FileShare.ReadWrite)

            If (File.GetAttributes(strPath) And FileAttributes.ReadOnly) = FileAttributes.ReadOnly Then
                strMsg = MessageManager.GetString("E000028", CommonSyori.MsgPath, strPath, "", "", "")
                MessageBox.Show(strMsg, CommonSyori.MsgTitle, MessageBoxButtons.OK, MessageBoxIcon.Hand)
                strmFile.Close()
                Return False
            Else
                Try
                    strmFile = New FileStream(strPath, FileMode.Truncate, FileAccess.ReadWrite)
                Catch ex As Exception
                    strMsg = MessageManager.GetString("E000027", CommonSyori.MsgPath, strPath, "", "", "")
                    MessageBox.Show(strMsg, CommonSyori.MsgTitle, MessageBoxButtons.OK, MessageBoxIcon.Hand)
                    strmFile.Close()
                    strmFile.Dispose()
                    GC.Collect()
                    Return False
                End Try
            End If
            If Me.setRenFileData(str) = False Then
                strmFile.Close()
                strmFile.Dispose()
                GC.Collect()
                Throw New Exception()
            End If
            strmwriWriter = New StreamWriter(strmFile, ecdgSJIS)
            For intCnt = 0 To arrlKjFile.Count - 1
                strmwriWriter.WriteLine(arrlKjFile(intCnt))
            Next
            strmwriWriter.Flush()
            strmwriWriter.Close()
            strmFile.Close()
            strmFile.Dispose()
            GC.Collect()
        Catch ex As Exception
            Return False
        End Try
        Return True
    End Function

[kukumaiwu]

读取位置代码

If Not outputFile(strOptRenPath, strOptNm) Then
                    
                    strMsg = MessageManager.GetString("E000014", CommonSyori.MsgPath, "****文件生成", "", "", "")
                    MessageBox.Show(strMsg, CommonSyori.MsgTitle, MessageBoxButtons.OK, MessageBoxIcon.Hand)
                End If