xsl-fo transformation much slower with Java 11 instead of 1.8

Question

After updating my program to Java 11, the transformations of an XML using xsl-fo (AWT renderer) have become much slower: Java 11: 90 seconds Java 1.8: 5 seconds

I've not tried it with Java 9 or 10.

There was no code and no stylesheet change between the run with Java 11 and 1.8.

I'm using org.apache.xmlgraphics:fop in version 2.3.

Also with Saxon-HE 9.9.1-5 (instead of Xalan) there was unfortunately no performance improvement.

Via profiling and debugging it looks like the code line 284 in the class org.apache.fop.layoutmgr.table.TableContentLayoutManager consumes the time:

nextRowGroupElems = rowGroupLM.getNextKnuthElements(context, alignment, bodyType);

So the culprit is Apache FOP using AWT. Using MIME_PDF instead of MIME_FOP_AWT_PREVIEW is much faster: 5 seconds vs 90 seconds.

The profiler (JProfiler) shows java.awt.EventDispatchThread as hot spot for Java 11. So maybe it is an AWT problem.

The relevant Code to reproduce:

import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;

import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.transform.Result;
import javax.xml.transform.Source;
import javax.xml.transform.Transformer;
import javax.xml.transform.TransformerFactory;
import javax.xml.transform.dom.DOMResult;
import javax.xml.transform.dom.DOMSource;
import javax.xml.transform.sax.SAXResult;

import org.apache.fop.apps.FOUserAgent;
import org.apache.fop.apps.FopConfParser;
import org.apache.fop.apps.FopFactory;
import org.apache.fop.apps.FopFactoryBuilder;
import org.apache.fop.apps.MimeConstants;
import org.springframework.core.io.ClassPathResource;
import org.w3c.dom.Document;
import org.xml.sax.SAXException;

public class MyTransform {

    public static void main(String[] args) throws Exception {
        Document xmlDoc = DocumentBuilderFactory.newInstance().newDocumentBuilder().parse(new FileInputStream("my_xml.xml"));
        Document xslDoc = DocumentBuilderFactory.newInstance().newDocumentBuilder().parse(new File("my_xsl.xsl")); 

        Transformer transformer = TransformerFactory.newInstance().newTransformer(new DOMSource(xslDoc));

        DOMSource xmlDomSource = new DOMSource(xmlDoc);
        DOMResult domResult = new DOMResult();
        transformer.transform(xmlDomSource, domResult);

        Source src = new DOMSource(domResult.getNode());
        Result res = new SAXResult(createFopFactory().newFop(MimeConstants.MIME_FOP_AWT_PREVIEW, getDisplayAgent()).getDefaultHandler());

        TransformerFactory factory = javax.xml.transform.TransformerFactory.newInstance();
        transformer = factory.newTransformer();
        transformer.transform(src, res);

        transformer.transform(src, res); // took with Java 11 90 seconds and with Java 1.8 5 seconds
    }

    private static FopFactory createFopFactory() throws SAXException, IOException {
        ClassPathResource resource = new ClassPathResource("fop_configuration.xml");
        FopConfParser parser = new FopConfParser(resource.getInputStream(), resource.getURI()); //parsing configuration
        FopFactoryBuilder builder = parser.getFopFactoryBuilder(); //building the factory with the user options
        return builder.build();
    }

    private static FOUserAgent getDisplayAgent() throws SAXException, IOException {
        FopFactory fopFactory = createFopFactory();
        FOUserAgent displayAgent = fopFactory.newFOUserAgent();
        MyAWTRendererMaker maker = new MyAWTRendererMaker();
        displayAgent.getRendererFactory().addRendererMaker(maker);
        MyAWTRenderer displayRenderer = new MyAWTRenderer(displayAgent);
        displayAgent.setRendererOverride(displayRenderer);
        return displayAgent;
    }
}

Answer 1

I solved the problem by first generating a PDF and then displaying it in a dialog box of ICEpdf instead of Apache FOP. It seems that using the output format MIME_FOP_AWT_PREVIEW causes the problems, instead I now use MIME_PDF.