StackOverflowError serializing POF objects

Question

Hi,
I have run into an issue while attempting to store objects in the cache that results in a StackOverflowError. The situation is that I have a number of classes that reference each other so while storing one the other is serialized which in turn attempts to serialize the other. An example is as follows:
public class DeskSerializer extends AbstractVersionedDomainEntitySerializer<DeskImpl> {
     private static final int NAME = 11;
     private static final int REGION = 12;
     private static final int COUNTRIES = 13;
     private static final int BOOKS = 14;
     private static final int DESK_ID = 15;
     @Override
     protected DeskImpl createInstance() {
          return new DeskImpl();
     public void serialize(PofWriter out, Object o) throws IOException {
          DeskImpl obj = (DeskImpl) o;
          super.serialize(out, obj);
          out.writeString(NAME, obj.getName());
          out.writeObject(REGION, obj.getRegion());
          out.writeCollection(COUNTRIES, obj.getCountries());
          out.writeCollection(BOOKS, obj.getBooks());
          out.writeLong(DESK_ID, obj.getDeskId());
          out.writeRemainder(null);
     @SuppressWarnings("unchecked")
     public Object deserialize(PofReader in) throws IOException {
          DeskImpl obj = (DeskImpl) super.deserialize(in);
          obj.setName(in.readString(NAME));
          obj.setRegion((Region) in.readObject(REGION));
          obj.setCountries((Set<Country>) in.readCollection(COUNTRIES, new HashSet<Country>()));
          obj.setBooks((Set<Book>) in.readCollection(BOOKS, new HashSet<Book>()));
          obj.setDeskId(in.readLong(DESK_ID));
          in.readRemainder();
          return obj;
public class BookSerializer extends AbstractVersionedDomainEntitySerializer<BookImpl> {
     private static final int NAME = 11;
     private static final int PORTFOLIO_SWAPS = 12;
     private static final int DESK = 13;
     private static final int LEGAL_ENTITY = 14;
     private static final int CLIENT = 15;
     private static final int BOOK_ID = 16;
     private static final int BUSINESS_UNIT_ID = 17;
     private static final int PORTFOLIO_ID = 18;
     private static final int NM_PRTF = 19;
     private static final int BOBOOK_ID = 20;
     @Override
     protected BookImpl createInstance() {
          return new BookImpl();
     public void serialize(PofWriter out, Object o) throws IOException {
          BookImpl obj = (BookImpl) o;
          super.serialize(out, obj);
          out.writeString(NAME, obj.getName());
          //out.writeCollection(PORTFOLIO_SWAPS, obj.getPortfolioSwaps());
          out.writeObject(DESK, obj.getDesk());
          //out.writeObject(LEGAL_ENTITY, obj.getLegalEntity());
          //out.writeObject(CLIENT, obj.getClient());
          out.writeLong(BOOK_ID, obj.getBookId());
          out.writeString(BUSINESS_UNIT_ID, obj.getBusinessUnitId());
          out.writeInt(PORTFOLIO_ID, obj.getPortfolioId());
          out.writeString(NM_PRTF, obj.getNmPrtf());
          out.writeString(BOBOOK_ID, obj.getBoBookId());
          out.writeRemainder(null);
     @SuppressWarnings("unchecked")
     public Object deserialize(PofReader in) throws IOException {
          BookImpl obj = (BookImpl) super.deserialize(in);
          obj.setName(in.readString(NAME));
          //obj.setPortfolioSwaps((Set<PortfolioSwap>) in.readCollection(PORTFOLIO_SWAPS, new HashSet<PortfolioSwap>()));
          obj.setDesk((Desk) in.readObject(DESK));
          //obj.setLegalEntity((LegalEntity) in.readObject(LEGAL_ENTITY));
          //obj.setClient((Client) in.readObject(CLIENT));
          obj.setBoBookId(in.readString(BOOK_ID));
          obj.setBusinessUnitId(in.readString(BUSINESS_UNIT_ID));
          obj.setPortfolioId(in.readInt(PORTFOLIO_ID));
          obj.setNmPrtf(in.readString(NM_PRTF));
          obj.setBoBookId(in.readString(BOBOOK_ID));
          in.readRemainder();
          return obj;
}in the above classes DeskSerializer tries to serialize a collection of Books which in turn try to serialize a Desk. This then just goes round and round until the exception is thrown.
Is there a neat solution to this situation? I can't change the domain objects as this is a legacy system so the only thing I could come up with would be to add a set of CoherenceDomainObjects that store the keys of the objects instead of the objest themselves and deconstruct the real objects into the Coherence version on the way in and reconstruct on the way out. Any ideas?

Answer 1

Hi Willy,
the problem is that you have a circle in your object graph which you are trying to serialize.
That needs to be broken, because POF does not support breaking the circle on its own, and you need to write custom PofSerializers for these classes which are able to deal with this problem. The problem is if you can not break the circle easily and traverse the full graph without entering into circles without recording references as you go then this is not going to be fast (this is the same reason why Java serialization is slow) or limit traversal of the graph.
Best regards,
Robert