C# Mobile - Memory warning (clear memory)

Question

I'm currently working on an application which runs on Windows Mobile 6.1 (not WP). I built an application which synchronizes data from a remote server multiple times a day. But somehow it looks like this data is "remembered" after finishing. Task Manager shows that about 3MB is used at a regular start of the application, which increases with about 2MB everytime I run the synchronization. After multiple times I get a warning of the memory usage and I have to reset the device or restart the program.

What I'm looking for is some way to clear data after synchronization, a kind of garbage collector. In (regular) C# I've found Collect(), but I can't get this working in C# mobile.

Below is my code, which is working correctly, except at a certain point I get the message "Geheugentekort" ("Memory shortage").

Probably after the for{} code, I have to empty variables like doc, root, and the XmlNodeList, but the question is how...

My device: Pidion BIP-5000 OS: Windows Mobile 6.1

XmlDocument doc = new XmlDocument();
doc.Load(xmlUrl);
XmlElement root = doc.DocumentElement;

try
{
    totaal = Int32.Parse(doc.GetElementsByTagName("Totaal")[0].InnerText.ToString());

    // Create lists with values
    XmlNodeList namen = doc.GetElementsByTagName("naam");
    XmlNodeList ptypen = doc.GetElementsByTagName("ptype");
    XmlNodeList ids = doc.GetElementsByTagName("id");

    // Door het totaal heen itereren
    for (int i = 0; i < totaal; i++)
    {
        // Create variables of it
        int id = Int32.Parse(ids[i].InnerText.ToString());
        int ptype = Int32.Parse(ptypen[i].InnerText.ToString());
        string naam = namen[i].InnerText.ToString();

        // Check if ID exists
        int tot = this.tbl_klantTableAdapter.GetData(id).Count;
        if (tot == 0)
        {
            // New item, add
            this.tbl_klantTableAdapter.Insert(naam, ptype, id);
        }
        else
        {
            // Existing, update
            this.tbl_klantTableAdapter.Update(naam, ptype, id);
        }
    }
}
catch
{
    // Rest of code

Answer 1

Dispose Your nodelists after the loop may help

System.Xml.XmlNodeList tempNodelist = Your stuff;
                IDisposable disposeMe = tempNodelist as IDisposable;
                if (disposeMe != null)
                {
                   disposeMe.Dispose();
                }

Answer 2

XmlNodeList implements IDisposable, so you can call namen.Dispose() (also for the other XmlNodeList objects) to force the objects to be discarded and cleaned up.

Answer 3

Yes, you definitely should use the XML stuff locally and dispose after using the XML stuff. The xml stuff seems to ocupie large memory blocks.

You should use nameX.Dispose() and nameX=null to free up the memory used for these temporary xml objects.

You may use GC.Collect() to force memory collection: http://blogs.msdn.com/b/stevenpr/archive/2004/07/26/197254.aspx.

You may also use remote .Net performance viewer to get insides on memory usage: http://blogs.msdn.com/b/stevenpr/archive/2006/04/17/577636.aspx

If your app is consuming much memory before calling into the sync task, you may consider of creating a new application with a separate process for the sync stuff. You can also free up memory for your process when you move functions to a library. WM6.1 and higher have a new memory slot for compact Framework libraries, so the main process memory slot is not lowered: http://blogs.msdn.com/b/robtiffany/archive/2009/04/09/memmaker-for-the-net-compact-framework.aspx

If you need more help you should provide more details/code.