Problem

• When exporting a page or space to PDF, it doesn't succeed and causes a high load on Confluence until it triggers an OutOfMemory Error.

• When exporting a single page, the process hangs and ultimately fails. The "System Error" page is displayed and the following appears in the atlassian-confluence.log:

  2012-04-19 17:22:06,698 ERROR [http-8080-3] [[Standalone].[localhost].[/confluence].[action]] log Servlet.service() for servlet action threw exception
  java.lang.OutOfMemoryError: Java heap space
      at java.util.LinkedList.addBefore(LinkedList.java:778)
      at java.util.LinkedList.add(LinkedList.java:198)
      at org.xhtmlrenderer.css.newmatch.CascadedStyle.addProperties(CascadedStyle.java:148)
      at org.xhtmlrenderer.css.newmatch.CascadedStyle.<init>(CascadedStyle.java:135)
      at org.xhtmlrenderer.css.newmatch.Matcher.getPageCascadedStyle(Matcher.java:121)
      at org.xhtmlrenderer.context.StyleReference.getPageStyle(StyleReference.java:203)
      at org.xhtmlrenderer.layout.Layer.createPageBox(Layer.java:794)
      at org.xhtmlrenderer.layout.Layer.addPage(Layer.java:764)
      at org.xhtmlrenderer.layout.Layer.addPagesUntilPosition(Layer.java:875)
      at org.xhtmlrenderer.layout.Layer.getPage(Layer.java:861)
      at org.xhtmlrenderer.layout.Layer.getFirstPage(Layer.java:805)
      at org.xhtmlrenderer.render.BlockBox.layout(BlockBox.java:774)
      at org.xhtmlrenderer.render.BlockBox.layout(BlockBox.java:735)
      at org.xhtmlrenderer.pdf.ITextRenderer.layout(ITextRenderer.java:209)
      at com.atlassian.confluence.extra.flyingpdf.FlyingSaucerXmlToPdfConverter.convertXhtmlToPdf(FlyingSaucerXmlToPdfConverter.java:92)
      at com.atlassian.confluence.extra.flyingpdf.FlyingSaucerXmlToPdfConverter.convertXhtmlToPdf(FlyingSaucerXmlToPdfConverter.java:38)
      at com.atlassian.confluence.extra.flyingpdf.FlyingSaucerPdfExporterService.createPdfForPage(FlyingSaucerPdfExporterService.java:78)
      at com.atlassian.confluence.extra.flyingpdf.ExportPageAsPdfAction.execute(ExportPageAsPdfAction.java:28)
  ....

• When exporting a space to PDF, it becomes stuck at Begin conversion of intermediate HTML to PDF:
  
  The following appears in the atlassian-confluence.log:

  2012-04-19 17:02:40,878 ERROR [Long running task: PDF Space Export] [content.render.xhtml.DefaultRenderer] render Error rendering content for view: RuntimeException occurred while performing an XHTML storage transformation (null)
   -- referer: http://localhost:8080/confluence/spaces/flyingpdf/flyingpdf.action?key=SBX | url: /confluence/spaces/flyingpdf/doflyingpdf.action | userName: admin | action: doflyingpdf
  com.atlassian.confluence.content.render.xhtml.XhtmlException: RuntimeException occurred while performing an XHTML storage transformation (null)
      at com.atlassian.confluence.content.render.xhtml.storage.StorageXhtmlTransformer.transform(StorageXhtmlTransformer.java:60)
      at com.atlassian.confluence.content.render.xhtml.TransformerChain.transform(TransformerChain.java:41)
      at com.atlassian.confluence.content.render.xhtml.PluggableTransformerChain.transform(PluggableTransformerChain.java:53)
      at com.atlassian.confluence.content.render.xhtml.DefaultRenderer.render(DefaultRenderer.java:63)
      at com.atlassian.confluence.content.render.xhtml.DefaultRenderer.render(DefaultRenderer.java:51)
      at com.atlassian.confluence.extra.flyingpdf.html.RenderedXhtmlBuilder.renderToHtml(RenderedXhtmlBuilder.java:377)
      at com.atlassian.confluence.extra.flyingpdf.html.RenderedXhtmlBuilder.renderContentTreeNodes(RenderedXhtmlBuilder.java:346)
      at com.atlassian.confluence.extra.flyingpdf.html.RenderedXhtmlBuilder.buildHtml(RenderedXhtmlBuilder.java:134)
      at com.atlassian.confluence.extra.flyingpdf.FlyingSaucerPdfExporterService.createPdfForSpace(FlyingSaucerPdfExporterService.java:50)
      at com.atlassian.confluence.extra.flyingpdf.PdfExportLongRunningTask$1.doInTransactionWithoutResult(PdfExportLongRunningTask.java:70)
      at org.springframework.transaction.support.TransactionCallbackWithoutResult.doInTransaction(TransactionCallbackWithoutResult.java:33)
      at org.springframework.transaction.support.TransactionTemplate.execute(TransactionTemplate.java:128)
      at com.atlassian.confluence.extra.flyingpdf.PdfExportLongRunningTask.runInternal(PdfExportLongRunningTask.java:52)
      at com.atlassian.confluence.util.longrunning.ConfluenceAbstractLongRunningTask.run(ConfluenceAbstractLongRunningTask.java:21)
      at com.atlassian.confluence.util.longrunning.ManagedTask.run(ManagedTask.java:35)
      at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:441)
      at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:303)
      at java.util.concurrent.FutureTask.run(FutureTask.java:138)
      at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886)
      at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908)
      at java.lang.Thread.run(Thread.java:662)
  Caused by: java.lang.NullPointerException
      at com.atlassian.confluence.content.render.xhtml.editor.macro.DefaultPlaceholderUrlFactory.getUrlForErrorPlaceholder(DefaultPlaceholderUrlFactory.java:73)
      at com.atlassian.confluence.content.render.xhtml.transformers.TransformErrorToHtmlPlaceholder.handle(TransformErrorToHtmlPlaceholder.java:54)
      at com.atlassian.confluence.content.render.xhtml.transformers.DefaultFragmentTransformer.transform(DefaultFragmentTransformer.java:124)
      at com.atlassian.confluence.content.render.xhtml.storage.StorageXhtmlTransformer.transform(StorageXhtmlTransformer.java:43)
      ... 20 more

Cause

This is normally caused by an incompatible or problematic PDF stylesheet. Particularly the following CSS, if the value for margin is bigger than 5in:

@page 
{
    margin: 5.5in;
}

This bug is being tracked at CONFSERVER-25278 - Page margin CSS in PDF Stylesheet can OOME and cause high load on Confluence during space export to pdf.

Workaround

Remove or reset the PDF stylesheets. You can base your customisations on the default CSS rules of the PDF stylesheet: confluencedefaultpdf.css.