Program slows down and eventually stops.


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Thread: Program slows down and eventually stops.

  1. #1
    James Guest

    Program slows down and eventually stops.


    I have a VB program that is processing 700,000 + records.
    I put in some code that writes the current time to an
    output file and noticed that the program processes the
    first few 1000 records fine. But eventually processing
    begins to slow down and than stops. I have check for
    looping and have no idea what else could be causing this
    or how to continue debugging. I'm using VB 6 in an
    NT environment.

    Would some point me the right direction.

    Thanks in advance for any help.

    James


  2. #2
    Arthur Wood Guest

    Re: Program slows down and eventually stops.


    James,
    Sounds like you have a MAJOR Memory Leak somewhere in your code.

    Arthur Wood


    "James" <tbt102@hotmail.com> wrote:
    >
    >I have a VB program that is processing 700,000 + records.
    >I put in some code that writes the current time to an
    >output file and noticed that the program processes the
    >first few 1000 records fine. But eventually processing
    >begins to slow down and than stops. I have check for
    >looping and have no idea what else could be causing this
    >or how to continue debugging. I'm using VB 6 in an
    >NT environment.
    >
    >Would some point me the right direction.
    >
    >Thanks in advance for any help.
    >
    >James
    >



  3. #3
    Urs Guest

    Re: Program slows down and eventually stops.


    Are you using Excel in any way?
    I had a similar problem while sorting
    10000+ files and make kind of an index in
    Excel. After the first 500- 1000 entries it
    went slower an slower and eventually the
    system crashed. Really sounds like a memory
    leak but my code was doublececked by two
    differnt persons who weren't able to figure
    this problem out either... I don't know, a bug?

    Urs

  4. #4
    Patrick Marshall Guest

    Re: Program slows down and eventually stops.


    "James" <tbt102@hotmail.com> wrote:
    >
    >I have a VB program that is processing 700,000 + records.
    >I put in some code that writes the current time to an
    >output file and noticed that the program processes the
    >first few 1000 records fine. But eventually processing
    >begins to slow down and than stops. I have check for
    >looping and have no idea what else could be causing this
    >or how to continue debugging. I'm using VB 6 in an
    >NT environment.
    >


    Are you concatenating any big strings?

    For example:

    dim i as long
    dim s as string

    for i = 0 to 100000
    s = s & "abc"
    if (i mod 1000) = 0 then
    debug.print time
    end if
    next

    This will get slower and slower and eventually appear to stop (though it
    is still running). The problem here is that when you are concatinating to
    a very large string, the time for a single operation gets longer and longer.

    The workaround is to create a variable dimension array and create the big
    string in blocks of 1000 loops then concatinating the array back into a single
    string, e.g.:

    Dim i As Long
    Dim s As String
    Dim strArr() As String
    Dim SizeOfStrArrInt As Integer

    For i = 0 To 100000
    's = s & "abc"
    If (i Mod 1000) = 0 Then
    ReDim Preserve strArr(SizeOfStrArrInt)
    SizeOfStrArrInt = SizeOfStrArrInt + 1
    Debug.Print Time
    End If
    strArr(SizeOfStrArrInt - 1) = strArr(SizeOfStrArrInt - 1) & "abc"
    Next
    For i = 0 To SizeOfStrArrInt - 1
    'put it back together from the pieces
    s = s & strArr(i)
    Next
    Debug.Print s

    Hope this helps,

    <Patrick>








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