Folks,
I'm baffled.
I've been an avid user of dom4j for a while, and have used the
below-mentioned stategy successfully ever since to process/transform huge
XML files without consuming much memory. However, this new code I have
appears to be getting gradually slower. I'm not sure if I'm missing
anything.
Here are the timings per 10000 elements processed. Note that I want to
process documents that have over 5 million of these elements:
10000: 3
20000: 9
30000: 15
40000: 21
50000: 27
60000: 33
70000: 39
80000: 45
90000: 56
100000: 87
110000: 158
// Create a reader and add an Element handler to efficiently iterate
// through the large document
SAXReader reader = new SAXReader();
reader.addHandler("/n-extract-response/guid-info",
new ElementHandler() {
public void onStart(ElementPath path) {
// do nothing
}
public void onEnd(ElementPath path) {
// Get the guid of the document
Element guidInfoElement = path.getCurrent();
String guid = guidInfoElement.valueOf("guid");
// Get the document size, and possibly metadata size
int totalSize = 0, docSize = 0, metaSize = 0;
try {
docSize = Integer.parseInt(guidInfoElement
.valueOf("size"));
metaSize = Integer.parseInt(guidInfoElement
.valueOf("metadatasize"));
} catch (NumberFormatException nfe) {
// do nothing
}
// print as line
totalSize = docSize + metaSize;
writer.println(colID + delimiter + guid + delimiter
+ totalSize);
// for debugging purposes, track how long it takes per
// 10000 guid-info elements
count++;
if (count % 10000 == 0) {
end = System.currentTimeMillis();
System.out.println(count + ": "
+ ((end - start) / 1000));
start = System.currentTimeMillis();
}
// make sure to detach to save memory
guidInfoElement.detach();
}
});
// Set the start time, and begin reading
start = System.currentTimeMillis();
reader.read(nxoGuidsFile);
writer.close();
You can argue that the string-concatenation and/or Integer parsing is taking
up time, but it doesnt explain the gradual increase in the timings.
I've tried compiling and running in both Java 1.4, 1.5 with various
compilation settings, but to no avail.
Help!
Thanks
-Wali
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