The PDF Export Application can now be configured to:

• limit the amount of content that can be included in a single PDF export; this can be done either from the PDF Export wiki administration section using the "Maximum content size" property or, globally, from xwiki.properties
  # [Since 14.10]
  # The maximum content size, in kilobytes (KB), an user is allowed to export to PDF; in order to compute the content size
  # we sum the size of the HTML rendering for each of the XWiki documents included in the export; the size of external
  # resources, such as images, style sheets, JavaScript code is not taken into account; 0 means no limit;
  export.pdf.maxContentSize=100
• limit the number of PDF exports that can be done in parallel; this can be specified only globally, from xwiki.properties
  # [Since 14.10]
  # The maximum number of PDF exports that can be executed in parallel (each PDF export needs a separate thread).
  export.pdf.threadPoolSize=3