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Extreme slowdown when accessing files over the network through VB when using an XP machine.

Posted on 2003-03-24
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Last Modified: 2010-05-01
One part of my program checks the status of various files on other machines over a corporate network as a means of tracking progress on on a centralized machine. One of the issues that I never was able to resolve when using a Win98 box was having to manually open a connection to each machine (open a folder on each machine even though the folder share passwords were stored). When trying to access files in shared folders it would just come up as unavailable if I tried doing from within the VB program if I had not yet manually opened the shared folder.

Well now with WinXP it no longer does this, however that issue has now been replaced with a much more annoying one. Where before access was instant, it now takes 20-30 seconds to open a connection to any of the other machines (that is it no longer makes me manually open a folder, but now it basically locks up while it waits for 20+ seconds for the network connection to complete and the files to become accessible).

I realize this may not be the best forum to ask this question, since I also experience the slowdown when trying to open a shared folder outside of VB using an XP machine, but I thought perhaps someone might know a more direct way of checking a file across the network than what I'm using which would bypass this slowdown (or ideally something to reduce the lag). While I would like to read data from text files instantly without delay, it would suffice if I could at least know whether a named file exists in a given shared folder. Oddly this delay also crops up if there isn't constant communication as well. That is if a few minutes pass without accessing the shared folder, I incurr the long delay once again on the next attempt at access.



Public Function FileExist(strPath As String) As Boolean
    'Check whether a file exists/can be accessed
    Dim X As Integer
    X = FreeFile
    On Error Resume Next
    Open strPath For Input As X
    If Err = 0 Then
        FileExist = True
    Else: FileExist = False
    End If
    Close X
End Function
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Question by:JamesKillian
5 Comments
 
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Expert Comment

by:GERTJAN
ID: 8198866
Maybe its quicker when you use a window api to check off the file exist. I am not sure about that. You can try the code below.
Please let me now if you've got a question about the code or let me now how this is working for you.

Gertjan

Public Const INVALID_HANDLE_VALUE = -1
Public Type WIN32_FIND_DATA
   dwFileAttributes As Long
   ftCreationTime As FILETIME
   ftLastAccessTime As FILETIME
   ftLastWriteTime As FILETIME
   nFileSizeHigh As Long
   nFileSizeLow As Long
   dwReserved0 As Long
   dwReserved1 As Long
   cFileName As String * MAX_PATH
   cAlternate As String * 14
End Type

Public Declare Function FindFirstFile Lib "kernel32" _
   Alias "FindFirstFileA" _
  (ByVal lpFileName As String, _
   lpFindFileData As WIN32_FIND_DATA) As Long
   
Public Declare Function FindClose Lib "kernel32" _
  (ByVal hFindFile As Long) As Long

Public Function FileExists(strPath As String) As Boolean

   Dim WFD As WIN32_FIND_DATA
   Dim hFile As Long
   
   hFile = FindFirstFile(strPath, WFD)
   FileExists = hFile <> INVALID_HANDLE_VALUE
   
   Call FindClose(hFile)
   
End Function
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Author Comment

by:JamesKillian
ID: 8205974
Thanks for the reply, it has the same amount of delay though, I made a quick test and it takes the same amount of time either way.
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Expert Comment

by:GERTJAN
ID: 8209405
I'am sorry but i don't now what else you can try.
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Accepted Solution

by:
Passerby earned 150 total points
ID: 8280100
James,

I've seen delays like this and they were always due to a network issue.

It could be something like a subnet mask mismatch, or NetBEUI taking preference to TCP/IP and not hearing anything. I've even seen the TCP/IP stack being loaded twice and competing. All resulting in a timeout or rerouting which takes a lot of time.

So take a look at your network settings and those of the other machine.
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Expert Comment

by:CleanupPing
ID: 8531703
Hi JamesKillian,
This old question (QID 20561323) needs to be finalized -- accept an answer, split points, or get a refund.  Please see http://www.cityofangels.com/Experts/Closing.htm for information and options.
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