<META HTTP-EQUIV="Content-Type" CONTENT="text/html; charset=iso-8859-1">
<html xmlns:v="urn:schemas-microsoft-com:vml" xmlns:o="urn:schemas-microsoft-com:office:office" xmlns:w="urn:schemas-microsoft-com:office:word" xmlns:x="urn:schemas-microsoft-com:office:excel" xmlns:p="urn:schemas-microsoft-com:office:powerpoint" xmlns:a="urn:schemas-microsoft-com:office:access" xmlns:dt="uuid:C2F41010-65B3-11d1-A29F-00AA00C14882" xmlns:s="uuid:BDC6E3F0-6DA3-11d1-A2A3-00AA00C14882" xmlns:rs="urn:schemas-microsoft-com:rowset" xmlns:z="#RowsetSchema" xmlns:b="urn:schemas-microsoft-com:office:publisher" xmlns:ss="urn:schemas-microsoft-com:office:spreadsheet" xmlns:c="urn:schemas-microsoft-com:office:component:spreadsheet" xmlns:odc="urn:schemas-microsoft-com:office:odc" xmlns:oa="urn:schemas-microsoft-com:office:activation" xmlns:html="http://www.w3.org/TR/REC-html40" xmlns:q="http://schemas.xmlsoap.org/soap/envelope/" xmlns:rtc="http://microsoft.com/officenet/conferencing" xmlns:D="DAV:" xmlns:Repl="http://schemas.microsoft.com/repl/" xmlns:mt="http://schemas.microsoft.com/sharepoint/soap/meetings/" xmlns:x2="http://schemas.microsoft.com/office/excel/2003/xml" xmlns:ppda="http://www.passport.com/NameSpace.xsd" xmlns:ois="http://schemas.microsoft.com/sharepoint/soap/ois/" xmlns:dir="http://schemas.microsoft.com/sharepoint/soap/directory/" xmlns:ds="http://www.w3.org/2000/09/xmldsig#" xmlns:dsp="http://schemas.microsoft.com/sharepoint/dsp" xmlns:udc="http://schemas.microsoft.com/data/udc" xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:sub="http://schemas.microsoft.com/sharepoint/soap/2002/1/alerts/" xmlns:ec="http://www.w3.org/2001/04/xmlenc#" xmlns:sp="http://schemas.microsoft.com/sharepoint/" xmlns:sps="http://schemas.microsoft.com/sharepoint/soap/" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:udcs="http://schemas.microsoft.com/data/udc/soap" xmlns:udcxf="http://schemas.microsoft.com/data/udc/xmlfile" xmlns:udcp2p="http://schemas.microsoft.com/data/udc/parttopart" xmlns:wf="http://schemas.microsoft.com/sharepoint/soap/workflow/" xmlns:dsss="http://schemas.microsoft.com/office/2006/digsig-setup" xmlns:dssi="http://schemas.microsoft.com/office/2006/digsig" xmlns:mdssi="http://schemas.openxmlformats.org/package/2006/digital-signature" xmlns:mver="http://schemas.openxmlformats.org/markup-compatibility/2006" xmlns:m="http://schemas.microsoft.com/office/2004/12/omml" xmlns:mrels="http://schemas.openxmlformats.org/package/2006/relationships" xmlns:spwp="http://microsoft.com/sharepoint/webpartpages" xmlns:ex12t="http://schemas.microsoft.com/exchange/services/2006/types" xmlns:ex12m="http://schemas.microsoft.com/exchange/services/2006/messages" xmlns:pptsl="http://schemas.microsoft.com/sharepoint/soap/SlideLibrary/" xmlns:spsl="http://microsoft.com/webservices/SharePointPortalServer/PublishedLinksService" xmlns:Z="urn:schemas-microsoft-com:" xmlns:st="&#1;" xmlns="http://www.w3.org/TR/REC-html40">

<head>

<meta name=Generator content="Microsoft Word 12 (filtered medium)">
<style>
<!--
 /* Font Definitions */
 @font-face
        {font-family:"Cambria Math";
        panose-1:2 4 5 3 5 4 6 3 2 4;}
@font-face
        {font-family:Calibri;
        panose-1:2 15 5 2 2 2 4 3 2 4;}
 /* Style Definitions */
 p.MsoNormal, li.MsoNormal, div.MsoNormal
        {margin:0cm;
        margin-bottom:.0001pt;
        font-size:11.0pt;
        font-family:"Calibri","sans-serif";}
a:link, span.MsoHyperlink
        {mso-style-priority:99;
        color:blue;
        text-decoration:underline;}
a:visited, span.MsoHyperlinkFollowed
        {mso-style-priority:99;
        color:purple;
        text-decoration:underline;}
span.E-MailFormatvorlage17
        {mso-style-type:personal;
        font-family:"Calibri","sans-serif";
        color:windowtext;}
span.E-MailFormatvorlage18
        {mso-style-type:personal-reply;
        font-family:"Calibri","sans-serif";
        color:#1F497D;}
.MsoChpDefault
        {mso-style-type:export-only;
        font-size:10.0pt;}
@page Section1
        {size:612.0pt 792.0pt;
        margin:70.85pt 70.85pt 2.0cm 70.85pt;}
div.Section1
        {page:Section1;}
-->
</style>
<!--[if gte mso 9]><xml>
 <o:shapedefaults v:ext="edit" spidmax="1026" />
</xml><![endif]--><!--[if gte mso 9]><xml>
 <o:shapelayout v:ext="edit">
  <o:idmap v:ext="edit" data="1" />
 </o:shapelayout></xml><![endif]-->
</head>

<body lang=DE link=blue vlink=purple>

<div class=Section1>

<p class=MsoNormal>Dear all,<o:p></o:p></p>

<p class=MsoNormal><o:p>&nbsp;</o:p></p>

<p class=MsoNormal><span lang=EN-US>Recently we reproducible got an
OutOfMemoryException after executing many different queries one after another. <o:p></o:p></span></p>

<p class=MsoNormal><span lang=EN-US>Looking at the heap dump taken on OOME or
after a certain amount of queries showed a suspicious schema object referencing
<o:p></o:p></span></p>

<p class=MsoNormal><span lang=EN-US>multiple hundred megabytes growing on each
query. The GC seems not to be able to remove these objects <o:p></o:p></span></p>

<p class=MsoNormal><span lang=EN-US>although - I thought that - these objects
are softly referenced in Mondrian&#8217;s cache. <o:p></o:p></span></p>

<p class=MsoNormal><span lang=EN-US><o:p>&nbsp;</o:p></span></p>

<p class=MsoNormal><span lang=EN-US>Further investigation showed that the whole
object tree is hard referenced from a threadlocal variable. Since we <o:p></o:p></span></p>

<p class=MsoNormal><span lang=EN-US>run Mondrian within an application server
that &nbsp;uses an thread pool there were many of these dangling threadlocals
and <o:p></o:p></span></p>

<p class=MsoNormal><span lang=EN-US>the GC was never able to clean the cache. <o:p></o:p></span></p>

<p class=MsoNormal><span lang=EN-US><o:p>&nbsp;</o:p></span></p>

<p class=MsoNormal><span lang=EN-US>To further stress our hypothesis we removed
the threadlocal after each request/query and run our test again. Now we <o:p></o:p></span></p>

<p class=MsoNormal><span lang=EN-US>could clearly see that the GC freed the
heap, the OOME disappeared and a heap dump showed no hard <o:p></o:p></span></p>

<p class=MsoNormal><span lang=EN-US>referenced objects from Mondrian anymore. <o:p></o:p></span></p>

<p class=MsoNormal><span lang=EN-US><o:p>&nbsp;</o:p></span></p>

<p class=MsoNormal><span lang=EN-US>The problematic threadlocal variable is
mondrian.rolap.RolapStar.localAggregations. The AggregationKey object holds a <o:p></o:p></span></p>

<p class=MsoNormal><span lang=EN-US>reference path to the RolapStar object
which references the threadlocal. This reference chain prevents the GC from <o:p></o:p></span></p>

<p class=MsoNormal><span lang=EN-US>removing the threadlocal (threadlocal
referenced by threadlocal&#8217;s value). <o:p></o:p></span></p>

<p class=MsoNormal><span lang=EN-US><o:p>&nbsp;</o:p></span></p>

<p class=MsoNormal><span lang=EN-US>Is this threadlocal variable intended to be
removed after each request? <o:p></o:p></span></p>

<p class=MsoNormal><span lang=EN-US>Does removing the threadlocal variable
after each request yield another behavior? <o:p></o:p></span></p>

<p class=MsoNormal><span lang=EN-US>Are the query results guaranteed to be the
same as before (our tests let us assume so)?<o:p></o:p></span></p>

<p class=MsoNormal><span lang=EN-US><o:p>&nbsp;</o:p></span></p>

<p class=MsoNormal><span lang=EN-US>&nbsp;<o:p></o:p></span></p>

<p class=MsoNormal><span lang=EN-US>Kind regards,<o:p></o:p></span></p>

<p class=MsoNormal><span lang=EN-US><o:p>&nbsp;</o:p></span></p>

<p class=MsoNormal><span lang=EN-US>Henning<o:p></o:p></span></p>

</div>

</body>

</html>