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POSerious performance issues with Java SAX
 

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  1. POSerious performance issues with Java SAX
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    <p>I'm building an application that converts an SVG directly to a PDF. Because the SVGs can get quite large and they can be handled linearly, I decided to implement the XML parser with SAX. However, I am not getting the proper performance from the parser: It takes 20 seconds to handle a 45KB SVG file. <p> Profiling reveals that the CPU hog is in XMLParser's parse method. More specifically, it's taking all this time not to process the data, but just to read it in. It goes all the way down to java.net.SocketInputStream.socketRead0, where the CPU is spending 19 seconds. <p> Has anyone else had this problem? Does anyone know how to fix it? <p> The driver I'm using:</p> <pre><code>// Initialize SAX components SAXParserFactory spf = SAXParserFactory.newInstance(); SAXParser saxParser = spf.newSAXParser(); XMLReader xmlReader = saxParser.getXMLReader(); // Set System L&amp;F UIManager.setLookAndFeel( UIManager.getSystemLookAndFeelClassName()); // Create a new file chooser JFileChooser fileChooser = new JFileChooser(); fileChooser.setFileFilter( new FileNameExtensionFilter("SVG file", "svg")); // Let the user choose an SVG file and convert it if (fileChooser.showDialog(null, "Convert") == JFileChooser.APPROVE_OPTION) { File svgInput = fileChooser.getSelectedFile(); File pdfOutput = new File(svgInput.getPath().replace(".svg", ".pdf")); xmlReader.setContentHandler(new SVGToPDFConverter(pdfOutput)); URL inputURL = new URL(svgInput.toURI().toString()); System.out.println("Working..."); // Parse the file try (InputStream inputStream = inputURL.openStream()) { xmlReader.parse(new InputSource(inputStream)); } System.out.println("Done!"); } </code></pre> <p>The start of the SVG file I've been testing with:</p> <pre><code>&lt;?xml version="1.0" encoding="UTF-8"?&gt; &lt;!DOCTYPE svg PUBLIC "-//W3C//DTD SVG 1.0//EN" "http://www.w3.org/TR/2001/REC-SVG-20010904/DTD/svg10.dtd"&gt; &lt;svg xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" style="fill-opacity:1; color-rendering:auto; color-interpolation:auto; stroke:black; text-rendering:auto; stroke-linecap:square; stroke-miterlimit:10; stroke-opacity:1; shape-rendering:auto; fill:black; stroke-dasharray:none; font-weight:normal; stroke-width:1; font-family:'Dialog'; font-style:normal; stroke-linejoin:miter; font-size:12; stroke-dashoffset:0; image-rendering:auto;" preserveAspectRatio="xMidYMid meet" zoomAndPan="magnify" version="1.0" contentScriptType="text/ecmascript" contentStyleType="text/css"&gt; &lt;!--Generated by the Batik Graphics2D SVG Generator--&gt; &lt;defs id="genericDefs" /&gt; &lt;g&gt; &lt;g style="font-size:14; fill:white; text-rendering:optimizeLegibility; color-rendering:optimizeQuality; image-rendering:optimizeQuality; font-family:'Calibri'; color-interpolation:linearRGB; stroke:white; font-weight:bold;"&gt; &lt;rect x="68" width="54" height="17" y="2" style="stroke:none;" /&gt; &lt;text x="73.4" xml:space="preserve" y="15" style="fill:black; stroke:none;"&gt;Dates (Ma)&lt;/text&gt; &lt;rect x="447" width="40" height="17" y="2" style="stroke:none;" /&gt; &lt;text x="452.7" xml:space="preserve" y="15" style="fill:black; stroke:none;"&gt;Composition&lt;/text&gt; &lt;rect x="604" width="54" height="17" y="2" style="stroke:none;" /&gt; &lt;text x="609.5001" xml:space="preserve" y="15" style="fill:black; stroke:none;"&gt;Isotopic Ratios&lt;/text&gt; &lt;text x="5" xml:space="preserve" y="32" style="fill:black; stroke:none;" /&gt; &lt;text x="5" xml:space="preserve" y="43" style="fill:black; stroke:none;" /&gt; &lt;text x="5" xml:space="preserve" y="54" style="fill:black; stroke:none;"&gt;Fraction &lt;/text&gt; &lt;line x1="70" x2="70" y1="18" style="fill:none; stroke:gray; stroke-width:0.5;" y2="76" /&gt; &lt;text x="73.4" y="32" style="fill:black; stroke-width:0.5; stroke:none;" xml:space="preserve" /&gt; &lt;text x="73.4" y="43" style="fill:black; stroke-width:0.5; stroke:none;" xml:space="preserve"&gt;206Pb/&lt;/text&gt; &lt;text x="73.4" y="54" style="fill:black; stroke-width:0.5; stroke:none;" xml:space="preserve"&gt;238U&lt;/text&gt; &lt;/g&gt; </code></pre>
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    1. COWhere is the SVG being read from, and what happens if you read that data directly (without even processing it)? Is SAX reading a byte at a time, perhaps - wrap it in BufferedInputStream?
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      1. USJon Skeet
    2. COIt's being read from an SVG file on my hard drive. I'm really not doing any processing right now (I'm in the middle of switching architectures). It's using BufferedInputStream.read down at the lower levels of SAX, I don't know if it's trying to read it byte by byte, though.
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    3. COIf it's being read from your hard drive, why is there a SocketInputStream involved?
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