Hi Andrew,
Creating a new XML parser can be very expensive. The ClassLoader used to
create the parser and its internal components might block or spend a long
time searching its "classpath" for META-INF/services files. This is why
it's generally a good idea to cache and reuse [1] XML parser instances.
Thanks.
[1]
http://www.ibm.com/developerworks/xml/library/x-perfap2/index.html#reuse
Michael Glavassevich
XML Technologies and WAS Development
IBM Toronto Lab
E-mail: mrgla...@ca.ibm.com
E-mail: mrgla...@apache.org
Andrew Welch wrote on 11/12/2013 07:48:47 AM:
> Hi,
>
> A colleague was doing some performance testing and discovered some
> contention at this line of my code:
>
> XMLReaderFactory.createXMLReader("org.apache.xerces.parsers.SAXParser");
>
> ...which was surprising : ) He informed me it was doing a blocking
> operation every time.
>
> Anyway, he went away and went through the Xerces source and found that
> if the "org.apache.xerces.xni.parser.XMLParserConfiguration" system
> property is not set it does indeed do a blocking operation (in
> parsers.ObjectFactory)
>
> To demonstrate this, run the below code with and without the system
> property set:
>
> public static void main(String... args) throws Exception {
>
> //System.setProperty
> ("org.apache.xerces.xni.parser.XMLParserConfiguration",
> //"org.apache.xerces.parsers.XIncludeParserConfiguration");
>
> long start = System.nanoTime();
>
> for (int i = 0; i <= 1; i++) {
> XMLReaderFactory.createXMLReader
> ("org.apache.xerces.parsers.SAXParser");
> }
>
> long end = System.nanoTime();
> double millis = (end - start) * 1e-6;
>
> System.out.println(millis);
>
> }
>
> On my machine it consistently takes around ~2000ms without the system
> property, and ~1300ms with.
>
> This is present in both 2.9 and 2.11 as far as I can see.
>
>
>
>
> --
> Andrew Welch
> http://andrewjwelch.com
>
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