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    <p>There is no "memory leak" in this case. Memory leak are defined as instances where an application cannot reclaim memory. In this case there is no leak, as all <code>XObject</code> (and <code>XObject[]</code>) instances can be reclaimed at some point in time.</p> <p>A memory profiler snapshot obtained from VisualVM yields the following observations:</p> <ul> <li>All <code>XObject</code> (and <code>XObject[]</code>) instances are created when the <code>XPathExpression.evaluate</code> method is invoked.</li> <li><code>XObject</code> instances are reclaimed when they are no longer reachable from a GC root. In your case, the GC roots are the <code>result</code> and <code>testResult</code> local variables which are local to the stack of the main thread.</li> </ul> <p>Based on the above, I suppose that your application is experiencing or likely to experience a memory exhaustion as opposed to a memory leak. This is true when you have a large number of <code>XObject</code>/<code>XObject[]</code> instances from an XPath expression evaluation, that haven't been reclaimed by the garbage collector because </p> <ul> <li>they are either still reachable from a GC root,</li> <li>or the garbage collector hasn't come around to reclaiming them yet.</li> </ul> <p>The only solution to the first is to retain objects around in memory for the duration that they are required. You do not seem to be violating that in your code, but your code could certainly be made more efficient - you are retaining the result of the first XPath expression, to be used by the second, when certainly it could be performed more efficiently. <code>//Product/Test</code> can be used to retrieve the <code>Test</code> nodes, and also obtain the parent <code>Product</code> Nodes' id values are shown in the following snippet (which evaluates only one XPath expression instead of two):</p> <pre><code>expr = xpath.compile("//Product/Test"); nodes = (NodeList) expr.evaluate(doc, XPathConstants.NODESET); for (int i = 0; i &lt; nodes.getLength(); i++) { Node node = nodes.item(i); System.out.println(node.getParentNode().getAttributes().getNamedItem("id")); System.out.println(node.getTextContent()); } System.out.println(nodes.getLength()); </code></pre> <p>As far as the second observation is concerned, you ought to obtain GC logs (using the <code>verbose:gc</code> JVM startup flag). You could then decide to resize the young generation, if you have too many shortlived objects being created, as there is the possible likelihood that reachable objects will be moved to the tenured generation resulting in the likelihood that a major collection will be required to reclaim objects that are actually shortlived by nature. In an ideal scenario (considering your posted code), a young gen collection cycle should be done every few iterations of the for loop, as the <code>XObject</code> instances that are local to the loop, should be reclaimed as soon as the block's local variables go out of scope.</p>
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    1. COThe program included was just a test program to reproduce a problem that I found in my application. In the application I actually need to process <Product> fragments which are stored in a database and extract attributes from these fragments using XPath expressions. There could be potentially millions of product records, and this will require millions of Xpath expression evaluations. I can have a look into the GC suggestion, but I would have thought that the GC would be able to reclaim the memory if I left the application running for long enough.
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    2. CO@Bob, there are atleast two kinds of GC cycles. If your shortlived objects can live beyond several young generation GC cycles, they will be promoted to the tenured generation once the young generation fills up. At that point in time, you need a major collection and not a minor collection to reclaim these objects. That's why you'll need to resize the young generation to be larger (I believe the default is 4M), so that there is a higher possibility that a young gen cycle (that occurs more frequently in this case) will find most objects to be unreachable from the GC roots.
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