Memory leak while indexing more than 500.000 documents.

When I'm reindexing a hudge number of documents I've getting an out of memory exception after some hours.

using (IndexWriter writer = this.CreateIndexWriter(_directory))
{
writer.DeleteAll();

foreach (Product product in _service.GetAllProducts())

{ Document doc = CreateDocument(product); writer.AddDocument(doc); }

writer.Commit();
writer.Optimize();
}

This came up with version 3.0.3. Before it was ok.