JAXB creating context and marshallers cost

Question

The question is a bit theoretical, what is the cost of creating JAXB context, marshaller and unmarshaller?

I\'ve found that my code could benefit from keeping the sa

Answer 1

I solved this problem using:

• shared thread safe JAXBContext and thread local un/marschallers
• (so theoretically, there will be as many un/marshaller instances as there are threads which accessed them)
• with synchronization only on un/marshaller's initialization.

public class MyClassConstructor {
    private final ThreadLocal<Unmarshaller> unmarshallerThreadLocal = new ThreadLocal<Unmarshaller>() {
        protected synchronized Unmarshaller initialValue() {
            try {
                return jaxbContext.createUnmarshaller();
            } catch (JAXBException e) {
                throw new IllegalStateException("Unable to create unmarshaller");
            }
        }
    };
    private final ThreadLocal<Marshaller> marshallerThreadLocal = new ThreadLocal<Marshaller>() {
        protected synchronized Marshaller initialValue() {
            try {
                return jaxbContext.createMarshaller();
            } catch (JAXBException e) {
                throw new IllegalStateException("Unable to create marshaller");
            }
        }
    };

    private final JAXBContext jaxbContext;

    private MyClassConstructor(){
        try {
            jaxbContext = JAXBContext.newInstance(Entity.class);
        } catch (JAXBException e) {
            throw new IllegalStateException("Unable to initialize");
        }
    }
}

Answer 2

Even better!! Based on the good solution from the post above, create the context just-once in the constructor, and save it instead of the class.

Replace the line:

  private Class clazz;

with this one:

  private JAXBContext jc;

And the main constructor with this one:

  private Jaxb(Class clazz)
  {
     this.jc = JAXBContext.newInstance(clazz);
  }

so in the getMarshaller/getUnmarshaller you can remove this line:

  JAXBContext jc = JAXBContext.newInstance(clazz);

This improvement makes, in my case, that processing times drops from 60~70ms to just 5~10ms