Fixed #1824: Now caching TransformerFactory to prevent countless expensive factory creations

[mkarg]

Closing #1824

Introduces a simple softreference-based cache for TransformerFactory to prevent expensive creation of new factories unless the configuration (= setting of security and factory class) has changed or memory was exhausted meanwhile.

[mkarg]

While mvn validate passes successfully, I'd like to keep this PR in draft mode until I found the time to actually run a performance benchmark with SAXON, to see that the cache is actually effective and really solves the discovered problem. Will need some time, please stay tuned!

[mkarg]

As announced recently, here is the benchmark result (please find the source code, build script, and test data attached
). Results are test iterations per second:

• 4.0.6-RI without Saxon: 5 in 2.749302799 seconds
• 4.0.6-RI using Saxon: 5 in 103.770735 seconds
• PR-1855 without Saxon: 5 in 1.604390299 seconds
• PR-1855 using Saxon: 5 in 2.379313601 seconds

This clearly proofs that JAXB-RI unmarshalls much faster using PR-1855 compared to 4.0.6-RI's original code. Both, Saxon and the JRE's original implementation, clearly benefit from this contribution, and Saxon is becoming useable now.

Hence, I am hereby removing the draft state, and kindly ask for a merge. 🙂

[mkarg]

@lukasj Kindly requesting your review. :-)

[laurentschoelens]

Hard to make a more minimal MRE 😄
I'll look at this

[laurentschoelens]

gh-1824-diff.txt

@mkarg : this is what I would have done to fix your performance issue.

With actual 4.0.6 :

• With Saxon : 5 in 64.100840667 seconds
• Without : 5 in 0.632727292 seconds

With patched 4.0.7-SNAPSHOT :

• With Saxon : 5 in 0.731846333 seconds
• Without : 5 in 0.497841 seconds

[mkarg]

Feel free to open an alternative PR if you think that yours is in any case better than mine. In the end, I am happy with any solution, as long as it finally solves #1824. 🙂

[laurentschoelens]

Well I don't want to take over your PR since you find the issue and provide a PR

My solution (IMHO) offers a retro-compatibility way since we don't know how users would modify cached-instance that would be grabbed outside JaxbContext.

And also provide cache handling on XmlFactory.createTransformerFactory in method createTransformer as well as createTransformerHandler in JAXBContextImpl

[mkarg]

Again, I do not care which solution is picked, so I am okay with you opening another PR and closing mine in turn - as long as we see any solution in the next patch level release.

[laurentschoelens]

@mkarg : created #1872

[mkarg]

@eclipse-ee4j/ee4j-jaxb-impl-committers Kindly asking for review / merge. 🙂