Memory Leak using StreamReader and XmlSerializer

Question

I've been googling for the past few hours and trying different things but can't seem to the bottom of this....

When I run this code, the memory usage continuously grows.

while (true)
{
    try
    {
        foreach (string sym in stringlist)
        {
            StreamReader r = new StreamReader(@"C:\Program Files\" + sym + ".xml");
            XmlSerializer xml = new XmlSerializer(typeof(XMLObj), new XmlRootAttribute("rootNode"));
            XMLObj obj = (XMLObj)xml.Deserialize(r);                       
            obj.Dispose();
            r.Dispose();
            r.Close();
        }
    }    
    catch(Exception ex) 
    {
        Console.WriteLine(ex.ToString()); 
    }
    Thread.Sleep(1000);
    Console.Clear();
}

XMLObj is a custom object

[Serializable()]
public class XMLObj: IDisposable
{
    [XmlElement("block")]
    public List<XMLnode> nodes{ get; set; }

    public XMLObj() { }

    public void Dispose()
    {
        nodes.ForEach(n => n.Dispose());
        nodes= null;

        GC.SuppressFinalize(this);
    }
}

I've tried adding in GC.Collect(); but that doesn't seem to do anything.

Answer 1

The leak is here:

new XmlSerializer(typeof(XMLObj), new XmlRootAttribute("rootNode"))

XmlSerializer uses assembly generation, and assemblies cannot be collected. It does some automatic cache/reuse for the simplest constructor scenarios (new XmlSerializer(Type), etc), but not for this scenario. Consequently, you should cache it manually:

static readonly XmlSerializer mySerializer =
    new XmlSerializer(typeof(XMLObj), new XmlRootAttribute("rootNode"))

and use the cached serializer instance.