VTD-XML Benchmark Report for Version 2.0

(Part III) XPath Evaluation Performance

Objective

This articles reports the measurement of XPath evaluation performance for VTD-XML version 2.0, and compares with Xerces 2.7.1 DOM and XPath functions bundled with JDK 1.6 (which is Xalan), as well as Jaxen 1.1.

Methodology Discussion

The benchmark code performs the following steps:

  1. Read XML file into an in-memory buffer.
  2. Parse the document once.
  3. Evaluate a single pre-compiled XPath expression for a large number of iterations.

All benchmark programs first loop thru the XPath evaluation code a number of iterations so the server JVM compile them into native code to obtain optimal performance, before the real measurement of the average latency of subsequent XPath evaluations.

Test Setup

Hardware

Software

The XML files

Three XML files of similar structure, but different sizes, are used for the test.

<?xml version="1.0"?>
<purchaseOrder orderDate="1999-10-20">
    <shipTo country="US">
        <name>Alice Smith</name>
        <street>123 Maple Street</street>
        <city>Mill Valley</city>
        <state>CA</state>
        <zip>90952</zip>
    </shipTo>
    <billTo country="US">
        <name> Robert Smith </name>
        <street>8 Oak Avenue</street>
        <city>Old Town</city>
        <state>PA</state>
        <zip>95819</zip>
    </billTo>
    <comment>Hurry, my lawn is going wild!</comment>
    <items>
        <item partNum="872-AA">
            <productName>Lawnmower</productName>
            <quantity></quantity>
            <USPrice>148.95</USPrice>
            <comment>Confirm this is electric</comment>
        </item>
        <item partNum="926-AA">
            <productName>Baby Monitor</productName>
            <quantity>1</quantity>
            <USPrice>39.98</USPrice>
            <shipDate>1999-05-21</shipDate>
        </item>
        ...
    </items>
</purchaseOrder>

The respective file sizes are:

The following XPath expressions are used for the test

The Benchmark Code Comparison

DOM Code Jaxen Code VTD-XML Code
Document d = null;
k = total;
d = parser.parse(bais);
while (k > 0) {
        NodeList nodeList = (NodeList) xPathExpression.evaluate(d,
        XPathConstants.NODESET);
        k--;
}
long l=0,lt=0;
for (int j = 0; j < 10; j++) {
        l = System.currentTimeMillis();
        for (int i = 0; i < total; i++) {
            NodeList nodeList = (NodeList) xPathExpression.evaluate(d,
            XPathConstants.NODESET);
}
long l2 = System.currentTimeMillis();
lt = lt + (l2 - l);
}
System.out.println(" average XPath latency ==> "
+ ((double) (lt) / total / 10) + " ms");

 

  XPath expression = new org.jaxen.dom.DOMXPath(xpe);
System.out.println("====> update_jaxen1 ==>"+xpe);
//parse and xpath eval

Document d = null;
d = parser.parse(bais);
k = total;
while (k > 0) {
   List results = expression.selectNodes(d);
   k--;
}
long l=0,lt=0;
for (int j = 0; j < 10; j++) {
l = System.currentTimeMillis();
for (int i = 0; i < total; i++) {
   List results = expression.selectNodes(d);
}
long l2 = System.currentTimeMillis();
lt = lt + (l2 - l);
}
System.out.println(" average XPath latency ==> "
+ ((double) (lt) / total / 10) + " ms");

 

 k=total;
VTDNav vn = null;
while(k>0){
        while((i1=ap.evalXPath())!=-1){
        }
        ap.resetXPath();
        k--;
}
for (int j=0;j<10;j++){
        l = System.currentTimeMillis();
        for(int i = 0;i<total;i++)
        {
            while((i1=ap.evalXPath())!=-1){
            }
            ap.resetXPath();
        }
        long l2 = System.currentTimeMillis();
        lt = lt + (l2 - l);
        //System.out.println("j ==> "+j);
}
System.out.println(" average XPath latency ==> "+
((double)(lt)/total/10) + " ms");

 

Results

Notice that the table includes # of nodes returned from XPath evaluation.

Latency Number Comparison

/*/*/*[position() mod 2 = 0]

  Jaxen (ms) JDK (ms) VTD-XML (ms)
po_small.xml 0.0395 1.123 0.00994
po_medium.xml 0.524 6.552 0.115
po_big.xml 8.812 94.535 1.292

/purchaseOrder/items/item[USPrice <100]

  Jaxen (ms) JDK (ms) VTD-XML (ms)
po_small.xml 0.0857 1.204 0.048
po_medium.xml 1.498 9.381 0.854
po_big.xml 22.262 113.831 9.238

/*/*/*/quantity/text()

  Jaxen (ms) JDK (ms) VTD-XML (ms)
po_small.xml 0.107 1.0756 0.0317
po_medium.xml 1.922 7.0268 0.537
po_big.xml 32.181 106.7 6.339

//item/comment

  Jaxen (ms) JDK (ms) VTD-XML (ms)
po_small.xml 0.356 1.208 0.089
po_medium.xml 9.824 9.922 1.505
po_big.xml 197.319 138.45 17.825

//item/comment/../quantity

  Jaxen (ms) JDK (ms) VTD-XML (ms)
po_small.xml 0.374 1.274 0.105
po_medium.xml 11.147 10.298 1.787
po_big.xml 204.714 140.06 21.06

/*/*/*/* [position() mod 2 = 0]

  Jaxen (ms) JDK(ms) VTD-XML(ms)
po_small.xml 0.136 1.21 0.0353
po_medium.xml 2.7 8.216 0.604
po_big.xml 65.469 122.83 6.559

/purchaseOrder/items/item[USPrice > 100]/comment/text()

  Jaxen (ms) JDK (ms) VTD-XML (ms)
po_small.xml 0.113 1.262 0.06
po_medium.xml 2.082 9.154 1.061
po_big.xml 32.892 121.07 12.35

Graphical View

/*/*/*[position() mod 2 = 0]

/purchaseOrder/items/item[USPrice <100]

/*/*/*/quantity/text()

//item/comment

//item/comment/../quantity

/*/*/*/* [position() mod 2 = 0]

/purchaseOrder/items/item[USPrice > 100]/comment/text()