Frequent invocation of javax.xml.stream.XMLOutputFactory::newInstance negatively impacts performance

[robsman]

While profiling a client application, it showed that there are lots of javax.xml.stream.XMLOutputFactory.newInstance() invocations, specifically when a client retrieves extracted document data from search results. In our use case, this almost totaled to the same amount of CPU time as the actual search.

[robsman]

I have applied a hotfix in the client project but still need to beef it up into a proper pull request.

The problematic code in our use case is in Utilities::writeEvents. However, there are other places that retrieve XML factories, e.g. SearchHandle::receiveContent, StructuredQueryBuilder::makeSerializer and SearchResponseImpl::handleMetrics.

My suggestion is to consolidate retrieval and caching of expensive factories into a utility class (maybe XmlFactoriesAccess ?) and adjust client code accordingly.

[sammefford]

Thanks Rob!

[sammefford]

We'll let you submit your patch first, then we'll use that as a model for the rest.