Question

In short, I’ve got an application that converts a flat data file into an XML file. It does this by populating objects and then serializing them to XML.

The problem I’m running into is that the Garbage Collector does not seem to be taking care of the serialized strings. 3500 record files are running up to OutOfMemoryExceptions before they finish. Something is fishy, indeed.

When I take the serialization out of the mix and simply pass an empty string, the memory consumption remains as expected, so I’ve ruled out the possibility that my intermediate objects (between flat file and xml) are the problem here. They seem to be collected as expected.

Can anyone help? How do I make sure these strings are disposed of properly?

Update: Some sample code

// myObj.Serialize invokes an XmlSerializer instance to handle its work    
string serialized = myObj.Serialize();
myXmlWriter.WriteRaw(serialized);

This is basically where the problem is ocurring–if I take the string serialized out of play, the memory problems go away, too, even though I’m still transforming the flat file into objects, one at a time.

Update 2: Serialize method

public virtual string Serialize()
{
      System.IO.StreamReader streamReader = null;
      System.IO.MemoryStream memoryStream = null;

      using (memoryStream = new MemoryStream())
      {
          memoryStream = new System.IO.MemoryStream();
          Serializer.Serialize(memoryStream, this);

          memoryStream.Seek(0, System.IO.SeekOrigin.Begin);
          using (streamReader = new System.IO.StreamReader(memoryStream))
          {
              return streamReader.ReadToEnd();
          }
      }
}

Answer 1

You need to make sure they aren’t referenced anywhere. Before an OutOfMemoryException is thrown, the GC is run. If it isn’t recovering that memory, that means something is still holding on to it. Like others said, if you post some code, we might be able to help. Otherwise you can use a profiler or WinDbg/SOS to help figure out what is holding onto your strings.