From: Duncan, David (David.Duncan@bskyb.com)
Date: Fri Mar 05 2004 - 07:03:11 PST
Hi,
I have another performance question. In regard to my previous email
concerning multi-threading, i have discovered that using Oracle OCI driver
causes problems in a muli-threaded application. I believe this is the main
cause for my performance issues and not the xep driver. However i have a
question regarding xep internal transformation step. I use xep to transform
an xml file to xsl-fo and then render the pdf, so i use xep to perform 2
steps. I was wondering if performance gains could be achieved by separating
out the transform step? Perhaps I could use Xalan or Saxon to do the
transform and pass xep the xslfo to render? I beleive xep uses JAXP...and
maybe using another transformation engine (with freedom to optimise the
engine) woudl help. Im also looking at stylesheet improvement such as,
- Don't use "//" (descendant axes) patterns near the root of a
large document.
- Use xsl:key elements and the key() function as an efficient way
to retrieve node sets.
- Where possible, use pattern matching rather than xsl:if or
xsl:when statements.
- xsl:for-each is fast because it does not require pattern
matching.
- Keep in mind that xsl:sort prevents incremental processing.
- When you create variables,
- <xsl:variable name="fooElem" select="foo"/>
is usually faster than
- <xsl:variable
name="fooElem"><xsl:value-of-select="foo"/></xsl:variable>
- The use of index predicates within match patterns can be
expensive.
If anyone has any suggestions or comments that would be much appreciated.
Thanks,
David.
-----Original Message-----
From: owner-xep-support@renderx.com
[mailto:owner-xep-support@renderx.com]On Behalf Of Duncan, David
Sent: Tuesday, March 02, 2004 10:41 AM
To: 'xep-support@renderx.com'
Subject: [xep-support] XEP 371 multi-threading
Hi,
I am having a major performance problem when upgraded to xep 371. I may
have amde some code errors which ill investigate, but my initial finding
appear to show problems with multi-threading on a mulitiple cpu machine.
Basically i launch a single JVM which initialises XEP bu loading XEP system
properties and by calling com.renderx.xep.gen.backends.H4PDF.init().
Then ,multiple threads are spawned each creating a PrintPublisher class
(note this is a publisher per xsl file. ie we cache the print publisher
object for multiple transforms using the same xsl template),
class DMSPrintPublisher {
private static final Logger s_logger =
Logger.getLogger(BatchPublishingClient.class); // log4j is thread-safe
private static FOTransformer foTransformer;
private FormatterImpl formatter;
public DMSPrintPublisher(String template, Properties xepProps) throws
CorrespondenceException {
InputSource xsl = new InputSource();
InputStream templateInputStream = new
ByteArrayInputStream(template.getBytes());
xsl.setByteStream(templateInputStream);
SAXSource saxSource = new SAXSource(xsl);
try {
this.formatter = new FormatterImpl(xepProps,
com.renderx.xep.lib.Logger.NULL_LOGGER);
foTransformer = new FOTransformer(saxSource, formatter);
foTransformer.setLogger(com.renderx.xep.lib.Logger.NULL_LOGGER);
foTransformer.setParameter("signature_location",
System.getProperty(DMSConstants.SIGNATURE_LOCATION));
} catch (Exception e) {
throw new CorrespondenceException("Could not set up
transformation engine: " + e.getMessage(), e);
}
public void publish(String documentData, OutputStream dest) throws
PublishException {
try {
InputStream dataInputStream = new
ByteArrayInputStream(documentData.getBytes());
StreamSource xml = new StreamSource(dataInputStream);
FOTarget foTarget = new FOTarget(dest, "PDF");
foTransformer.transform(xml, foTarget);
dataInputStream.close();
dest.close();
formatter.cleanup();
} catch (Exception exc) {
throw new PublishException(ErrorCodes.RECOVERABLE_SYSTEM_ERROR,
"Failed to perform transform: " + exc.getMessage(), exc);
}
}
}
My main concern is that when using xep 361 interface we saw the
multi-threaded process being shared across a 4 cpu unix box (running
Solaris8). However, using xep371 (along with code changes due to new
interface), we see 1 cpu maxed out and the rest idle. This reduces
performance by 4 fold.
Perhaps I have made some errors in coding the publisher...maybe I should
create one FOTransformer (initialised by xep properties) instead of 1 for
each publisher object? Bu this seems to be a side issue. Are you aware of
any potential multi-threading issues with the new version of xep?
Many thanks for your support,
David.
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