Re: Memory Problem

From: Mike Mc (MikeMc_at_discussions.microsoft.com)
Date: 01/08/05 

Date: Sat, 8 Jan 2005 09:27:03 -0800

Good question and thanks for the reply -- I should have included more info.
I am using a 64MB device -- and have been pinvoking GlobalMemoryStatusCE for
memory info. Here are some stats on the sample program with my first message:
* Available determined from AvailablePhysical returned from
GlobalMemoryStatusCE
** % Load from Memory Load returned from GlobalMemoryStatusCE

Before first run: ~36MB Available, 17% Load
After first allocation of array: ~31MB Avaialable, 29% Load
2nd allocation: ~26MB Available, 41% Load

Each time I see the 5MB array allocation reflected properly.
After the third -- I don't get an error (in my sample program below) and it
just repeats the 2nd allocation stats. My guess is the the garbage collector
is freeing up memory at this point -- but why does it not go back to the
~36MB before the first run? Net, net -- I believe I have plenty of memory --
the real question is --- why are my previous memory allocations not freeing
up? Any thoughts?

"Daniel Moth" wrote:

> > ReDim baConv(5000000)
> The obvious question: Is that much memory (>4.5MB) available on the target?
>
> E.g. try in the WinCE emulator and in Settings>ControlPanel->System under
> the Memory tab configure the available Program Memory and you can get the
> same results (or not if you move it far to the left)
>
> Programmatically try calling GlobalMemoryStatus to see how much memory is
> free
>
> Cheers
> Daniel
> --
> http://www.danielmoth.com/Blog/
>
>
> "Mike Mc" <MikeMc@discussions.microsoft.com> wrote in message
> news:104EF3DA-5A7F-4608-A103-1885499456E3@microsoft.com...
> >I am using VS 2003 (VB.Net) on a PPC2003 SP2 device.
> >
> > My main program is having memory problems encrypting large byte arrays
> > that
> > are passed to/from a .Net webservice. When I create a 2nd byte array (for
> > the conversion) the memory is not freed up. Since we receive many of
> > these
> > arrays, I eventually get an OutofMemoryException and the gc.GetTotalMemory
> > call shows I am increasing the memory by the expected amount. After
> > researching and playing with the garbage collector (gc.collect), my
> > assumption is that somehow my byte array is still in scope (though I don't
> > understand how). I have created a very small program to reproduce the
> > problem -- any help from this community would be greatly appreciated. The
> > program has a button that creates a new 5MB array and two textboxes that
> > show
> > the gc.GetTotalMemory before and after the creation. Here is the code:
> > _________
> >
> > Imports testmemory.Class1
> >
> > Public Class Form1
> > Inherits System.Windows.Forms.Form
> > Friend WithEvents Button1 As System.Windows.Forms.Button
> > Friend WithEvents MainMenu1 As System.Windows.Forms.MainMenu
> >
> > #Region " Windows Form Designer generated code "
> >
> > Public Sub New()
> > MyBase.New()
> >
> > 'This call is required by the Windows Form Designer.
> > InitializeComponent()
> >
> > 'Add any initialization after the InitializeComponent() call
> >
> > End Sub
> >
> > 'Form overrides dispose to clean up the component list.
> > Protected Overloads Overrides Sub Dispose(ByVal disposing As Boolean)
> > MyBase.Dispose(disposing)
> > End Sub
> >
> > 'NOTE: The following procedure is required by the Windows Form Designer
> > 'It can be modified using the Windows Form Designer.
> > 'Do not modify it using the code editor.
> > Friend WithEvents Label1 As System.Windows.Forms.Label
> > Friend WithEvents Label2 As System.Windows.Forms.Label
> > Friend WithEvents TextBox1 As System.Windows.Forms.TextBox
> > Friend WithEvents TextBox2 As System.Windows.Forms.TextBox
> > Friend WithEvents Button2 As System.Windows.Forms.Button
> > Private Sub InitializeComponent()
> > Me.MainMenu1 = New System.Windows.Forms.MainMenu
> > Me.Button1 = New System.Windows.Forms.Button
> > Me.Label1 = New System.Windows.Forms.Label
> > Me.Label2 = New System.Windows.Forms.Label
> > Me.TextBox1 = New System.Windows.Forms.TextBox
> > Me.TextBox2 = New System.Windows.Forms.TextBox
> > Me.Button2 = New System.Windows.Forms.Button
> > '
> > 'Button1
> > '
> > Me.Button1.Location = New System.Drawing.Point(16, 192)
> > Me.Button1.Size = New System.Drawing.Size(64, 24)
> > Me.Button1.Text = "run test"
> > '
> > 'Label1
> > '
> > Me.Label1.Location = New System.Drawing.Point(24, 32)
> > Me.Label1.Size = New System.Drawing.Size(64, 24)
> > Me.Label1.Text = "Before "
> > '
> > 'Label2
> > '
> > Me.Label2.Location = New System.Drawing.Point(24, 72)
> > Me.Label2.Size = New System.Drawing.Size(56, 24)
> > Me.Label2.Text = "After"
> > '
> > 'TextBox1
> > '
> > Me.TextBox1.Location = New System.Drawing.Point(88, 32)
> > Me.TextBox1.Size = New System.Drawing.Size(104, 22)
> > Me.TextBox1.Text = ""
> > '
> > 'TextBox2
> > '
> > Me.TextBox2.Location = New System.Drawing.Point(88, 72)
> > Me.TextBox2.Size = New System.Drawing.Size(104, 22)
> > Me.TextBox2.Text = ""
> > '
> > 'Button2
> > '
> > Me.Button2.Location = New System.Drawing.Point(80, 240)
> > Me.Button2.Size = New System.Drawing.Size(64, 24)
> > Me.Button2.Text = "End"
> > '
> > 'Form1
> > '
> > Me.Controls.Add(Me.Button2)
> > Me.Controls.Add(Me.TextBox2)
> > Me.Controls.Add(Me.TextBox1)
> > Me.Controls.Add(Me.Label2)
> > Me.Controls.Add(Me.Label1)
> > Me.Controls.Add(Me.Button1)
> > Me.Menu = Me.MainMenu1
> > Me.Text = "Form1"
> >
> > End Sub
> >
> > #End Region
> >
> > Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As
> > System.EventArgs) Handles MyBase.Load
> >
> > End Sub
> >
> > Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As
> > System.EventArgs) Handles Button1.Click
> >
> > Me.TextBox1.Text = ""
> > Me.TextBox2.Text = ""
> > 'run memory test
> > Me.TextBox1.Text = System.GC.GetTotalMemory(False).ToString
> > BeginTest()
> > Me.TextBox2.Text = System.GC.GetTotalMemory(False).ToString
> >
> > End Sub
> >
> > Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As
> > System.EventArgs) Handles Button2.Click
> > Me.Close()
> > End Sub
> > End Class
> >
> >
> > Public Class Class1
> >
> > Friend Shared Sub BeginTest()
> > 'Call routine to allocate memory
> >
> > Try
> > Dim baTest() As Byte = New Byte() {1}
> >
> > Callfunct(baTest)
> >
> > Catch ex As OutOfMemoryException
> > MessageBox.Show("BeginTest: " & ex.ToString)
> >
> > Catch ex As Exception
> > MessageBox.Show("BeginTest: " & ex.ToString)
> > End Try
> >
> >
> > End Sub
> >
> > Friend Shared Function Callfunct(ByVal batest As Byte()) As Byte()
> >
> > Try
> > Dim baConv() As Byte
> >
> > ReDim baConv(5000000)
> >
> > Catch ex As OutOfMemoryException
> > MessageBox.Show("Callfunct: " & ex.ToString)
> >
> > Catch ex As Exception
> > MessageBox.Show("Callfunct: " & ex.ToString)
> > End Try
> >
> > Return (batest)
> > End Function
> > End Class
> > ____
> >
> > Thanks again for your help!
> > Mike
>
>
>

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