XMLReader : java.lang.OutOfMemoryError: Java heap space

Question

I'm using a XMLReader object to Parse XML files. About 20000 XML documents need to be parsed, so the parse(...) method is called about 20000 times in a loop.
The XML string to be parsed are all about 2500 bytes long. Java 1.5 is used.
import java.io.StringReader;
import org.xml.sax.XMLReader;
private final XMLReader parser;
private StringReader stringReader;
public void myParseMethod(final String xml) {          
try {
stringReader = new StringReader(xml);
parser.parse(new InputSource(stringReader));
stringReader.close();
} catch (final SAXParseException e) {
} catch (final SAXException e) {
} catch (final IOException e) {
Calling the method myParseMethod(final String xml) goes well till about 2000 times. Then the following exception is thrown:
java.lang.OutOfMemoryError: Java heap space
at java.io.BufferedWriter.<init>(Unknown Source)
at java.io.BufferedWriter.<init>(Unknown Source)
at java.io.PrintWriter.<init>(Unknown Source)
at java.io.PrintWriter.<init>(Unknown Source)
at com.sun.org.apache.xerces.internal.util.DefaultErrorHandler.<init>(Unknown Source)
at com.sun.org.apache.xerces.internal.impl.xs.XMLSchemaLoader.<init>(Unknown Source)
at com.sun.org.apache.xerces.internal.impl.xs.XMLSchemaLoader.<init>(Unknown Source)
at com.sun.org.apache.xerces.internal.impl.xs.XMLSchemaValidator.<init>(Unknown Source)
at com.sun.org.apache.xerces.internal.jaxp.validation.xs.InsulatedSchemaValidator.<init>(Unknown Source)
at com.sun.org.apache.xerces.internal.jaxp.validation.xs.SchemaImpl.newXNIValidator(Unknown Source)
at com.sun.org.apache.xerces.internal.jaxp.validation.XercesSchema._newValidatorHandler(Unknown Source)
at com.sun.org.apache.xerces.internal.jaxp.validation.XercesSchema.newValidatorHandler(Unknown Source)
at com.sun.org.apache.xerces.internal.parsers.JAXPConfiguration.configurePipeline(Unknown Source)
at com.sun.org.apache.xerces.internal.parsers.XML11Configuration.parse(Unknown Source)
at com.sun.org.apache.xerces.internal.parsers.XML11Configuration.parse(Unknown Source)
at com.sun.org.apache.xerces.internal.parsers.XMLParser.parse(Unknown Source)
at com.sun.org.apache.xerces.internal.parsers.AbstractSAXParser.parse(Unknown Source)
Many thanks for help,
Frank
Edited by: 863908 on Jun 6, 2011 8:09 AM
Edited by: 863908 on Jun 6, 2011 8:11 AM

Answer 1

Badly written code? Look into the Xerces API and you'll find out that I'm using the XML parser the normal way.Not at all. Those APIs deal with any stream. You have gone to a whole lot of extra and unnecessary trouble and expense to read the entire file, probably accumulate it into a StringBuffer, convert that to a String, and create a StringReader around it. Or else you have read the entire file into a char[] array and created a String directly from that. This strategy creates not one but two copies of the entire file in memory, and also wastes time. The normal way is to wrap an InputSource around a FileReader or InputStreamReader, probably with a BufferedReader in between. End of all that pointless and badly written code, end of the two copies of the file in memory, end of the wasting of time, and end of your memory problems too.
Full stop.