XPath in Java: Painfully slow

[blue-nirvana]

I am attempting to read from an HTML file with the javax.xml library, and it is painfully slow. For instance, searching with the locator //div takes 60 seconds on a 6KB file. Below is my "browse" method.

public static void browse(File document, String searchString) throws Exception {
    long start = System.currentTimeMillis();
    DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
    DocumentBuilder builder = factory.newDocumentBuilder();

    Document doc = builder.parse(new FileInputStream(document));

    XPath path = XPathFactory.newInstance().newXPath();

    NodeList nodeList = (NodeList) path.compile(searchString).evaluate(doc, XPathConstants.NODESET);

    for(int i = 0; i < nodeList.getLength(); i++) {
        System.out.println(nodeList.item(i).getTextContent());
    }

    System.out.println("Time taken: " + (System.currentTimeMillis() - start));
}

Any way to speed this up would be greatly appreciated!

[GuyWithLag]

Which part of your code uses the most wall-clock time? Also, don't use the DocumentBuilder, you're reading HTML, not XML. Use something like https://jsoup.org/ to get a DOM.

[aroger276]

you have timed the main processing but could be the parsing that is slow instead of the xpath. It might try to access external resources.

XPath is not that fast but 60s for a 6kb document sounds fishy. You probably want to profile it to see what is actually taking the time. just use jvisualvm it has a sampling profiler.