DataTypeFactory usage in creating XMLGregorianCalendar hits performance badly

Question

Given a time in milliseconds, we can create XMLGregorianCalendar using the following snippet.

GregorianCalendar greCal = new GregorianCalendar();
greCal.setTimeInMillis(timeInMilliseconds);
XMLGregorianCalendar xmlCal = DatatypeFactory.newInstance().newXMLGregorianCalendar(greCal));

But the problem is, it hits the performance badly.

http://www.java.net/node/666491

There is a bug filed for this with SUN but they have not listed any workarounds. http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=6466177

Tried searching for some other alternative but in vain. Do any of you folks have an alternative to do the same?

Thanks

Raman

Answer 1

The expensive part is DatatypeFactory.newInstance(), it shows right on top when profiling the application. In our case we stored the DatatypeFactory as static variable and we were able to circumvent the repeated initialization. This should work because the DatatypeFactory implementation we use is supposed to be thread safe (as stated in the bug report). I agree that there's a chance that this may change depending on the implementation used. So I'll recommend to doublecheck.

private static DatatypeFactory datatypeFactory;
static{
    try {
        datatypeFactory = DatatypeFactory.newInstance();
    } catch (DatatypeConfigurationException e) {
        throw new RuntimeException("Init Error!", e);
    }
}

public void foo(long timeInMilliseconds){
    GregorianCalendar greCal = new GregorianCalendar(); greCal.setTimeInMillis(timeInMilliseconds); 
    XMLGregorianCalendar xmlGregorienCalendar = datatypeFactory.newXMLGregorianCalendar(greCal);
    // ...
}

Answer 2

Since as @VivaceVivo mentioned DataFactory.newInstance() is expensive and impl not guaranteed to be thread-safe, consider using a ThreadLocal:

final private static ThreadLocal<DatatypeFactory> datatypeFactoryHolder = new ThreadLocal<DatatypeFactory>()
    {
        @Override
        protected DatatypeFactory initialValue()
        {
            try
            {
                return DatatypeFactory.newInstance();
            } catch (DatatypeConfigurationException e)
            {
                throw new IllegalStateException("failed to create " + DatatypeFactory.class.getSimpleName(), e);
            }
        }
    };

    public static XMLGregorianCalendar dateToXMLGregorianCalendar(Date date)
    {
        GregorianCalendar c = new GregorianCalendar();
        c.setTime(date);
        return datatypeFactoryHolder.get().newXMLGregorianCalendar(c);
    }
}

..as long as you don't care if threads retain an extra object or have a way of clearing ThreadLocalMap when needed