Performance problem for XMLGregorianCalendar caused by ConstructionStrategies

[amohrig]

Whats your runtime?

• Dozer version: 6.2 - 6.5
• OS version: Windows, Linux
• JDK version: 8 - 11

Whats the problem?

We are using Dozer to map object trees resulting from a JAXB deserialization of XML documents containing lots of XMLGregorianCalendar values.
While processing large numbers of such objects (in the magnitude of tens of millions) we noticed that a lot of time is spent in calls to DatatypeFactory.newInstance() being issued from ConstructionStrategies.

Observed Results:

The inner class XmlGregorian in com.github.dozermapper.core.factory.ConstructionStrategies is creating a new instance of DatatypeFactory for each XMLGregorianCalendar object it is asked to create via calls to create(BeanCreationDirective directive).

Expected Results:

The overhead should be avoided so that creating XMLGregorianCalendar objects to map into remains reasonably cheap.

Link to GitHub repo with fix

We will provide a fix via https://github.com/kuehne-nagel/dozer/tree/datatypefactory and a pull request from there.