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<p class="MsoNormal">I’m in the middle of trying to upgrade our application to Drools 5.2 from 5.1 however I keep facing out of memory issues (I’ve also tried on the current 5.3 beta).<o:p></o:p></p>
<p class="MsoNormal">I’ve simplified my code into the following test case which on my machine after about 600 or so iterations gives an Out of memory exception:<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:10.0pt;font-family:Consolas;color:#646464">@Test</span><span style="font-size:10.0pt;font-family:Consolas"><o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:10.0pt;font-family:Consolas;color:black">
</span><b><span style="font-size:10.0pt;font-family:Consolas;color:#7F0055">public</span></b><span style="font-size:10.0pt;font-family:Consolas;color:black">
</span><b><span style="font-size:10.0pt;font-family:Consolas;color:#7F0055">void</span></b><span style="font-size:10.0pt;font-family:Consolas;color:black"> testCase()
</span><b><span style="font-size:10.0pt;font-family:Consolas;color:#7F0055">throws</span></b><span style="font-size:10.0pt;font-family:Consolas;color:black"> InterruptedException</span><span style="font-size:10.0pt;font-family:Consolas"><o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:10.0pt;font-family:Consolas;color:black"> {</span><span style="font-size:10.0pt;font-family:Consolas"><o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:10.0pt;font-family:Consolas;color:black"> KnowledgeBuilder kbuilder = KnowledgeBuilderFactory.<i>newKnowledgeBuilder</i>();</span><span style="font-size:10.0pt;font-family:Consolas"><o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:10.0pt;font-family:Consolas;color:black"> KnowledgeBase kbase = KnowledgeBaseFactory.<i>newKnowledgeBase</i>();</span><span style="font-size:10.0pt;font-family:Consolas"><o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:10.0pt;font-family:Consolas;color:black"> kbase.addKnowledgePackages(kbuilder.getKnowledgePackages());</span><span style="font-size:10.0pt;font-family:Consolas"><o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:10.0pt;font-family:Consolas;color:black">
</span><span style="font-size:10.0pt;font-family:Consolas"><o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:10.0pt;font-family:Consolas;color:black">
</span><b><span style="font-size:10.0pt;font-family:Consolas;color:#7F0055">for</span></b><span style="font-size:10.0pt;font-family:Consolas;color:black">(</span><b><span style="font-size:10.0pt;font-family:Consolas;color:#7F0055">int</span></b><span style="font-size:10.0pt;font-family:Consolas;color:black">
i = 0; i < 1000; i++) {</span><span style="font-size:10.0pt;font-family:Consolas"><o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:10.0pt;font-family:Consolas;color:black"> System.</span><i><span style="font-size:10.0pt;font-family:Consolas;color:#0000C0">out</span></i><span style="font-size:10.0pt;font-family:Consolas;color:black">.println(</span><span style="font-size:10.0pt;font-family:Consolas;color:#2A00FF">"Run
"</span><span style="font-size:10.0pt;font-family:Consolas;color:black"> + i);</span><span style="font-size:10.0pt;font-family:Consolas"><o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:10.0pt;font-family:Consolas;color:black"> StatefulKnowledgeSession session = kbase.newStatefulKnowledgeSession();</span><span style="font-size:10.0pt;font-family:Consolas"><o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:10.0pt;font-family:Consolas;color:black">
</span><b><span style="font-size:10.0pt;font-family:Consolas;color:#7F0055">for</span></b><span style="font-size:10.0pt;font-family:Consolas;color:black">(</span><b><span style="font-size:10.0pt;font-family:Consolas;color:#7F0055">int</span></b><span style="font-size:10.0pt;font-family:Consolas;color:black">
j = 0; j < 100; j++) {</span><span style="font-size:10.0pt;font-family:Consolas"><o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:10.0pt;font-family:Consolas;color:black"> session.insert(</span><b><span style="font-size:10.0pt;font-family:Consolas;color:#7F0055">new</span></b><span style="font-size:10.0pt;font-family:Consolas;color:black">
</span><b><span style="font-size:10.0pt;font-family:Consolas;color:#7F0055">byte</span></b><span style="font-size:10.0pt;font-family:Consolas;color:black">[10240]);</span><span style="font-size:10.0pt;font-family:Consolas"><o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:10.0pt;font-family:Consolas;color:black"> }</span><span style="font-size:10.0pt;font-family:Consolas"><o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:10.0pt;font-family:Consolas;color:black">
</span><span style="font-size:10.0pt;font-family:Consolas"><o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:10.0pt;font-family:Consolas;color:black"> session.dispose();</span><span style="font-size:10.0pt;font-family:Consolas"><o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:10.0pt;font-family:Consolas;color:black"> session =
</span><b><span style="font-size:10.0pt;font-family:Consolas;color:#7F0055">null</span></b><span style="font-size:10.0pt;font-family:Consolas;color:black">;</span><span style="font-size:10.0pt;font-family:Consolas"><o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:10.0pt;font-family:Consolas;color:black"> System.<i>gc</i>();</span><span style="font-size:10.0pt;font-family:Consolas"><o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:10.0pt;font-family:Consolas;color:black"> }
</span><span style="font-size:10.0pt;font-family:Consolas"><o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:10.0pt;font-family:Consolas;color:black"> }</span><span style="font-size:10.0pt;font-family:Consolas"><o:p></o:p></span></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Am I missing anything here – I’m calling session.dispose() which is all I believe is necessary when finishing the session, however using a profiler shows that all the StatefulKnowledgeSessionImpl and ReteooStatefulSessions are still present
and therefore keeping hold of all the byte arrays and memory.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Using a profiler it shows that the GC roots of the StatefulKnowledgeSessionImpl are
<o:p></o:p></p>
<p class="MsoNormal">kruntime of org.jbpm.process.instance.ProcessRuntimeImpl<o:p></o:p></p>
<p class="MsoNormal">kruntime of org.jbpm.process.instance.event.DefaultSignalManager<o:p></o:p></p>
<p class="MsoNormal">kruntime of org.jbpm.process.instance.timer.TimerManager<o:p></o:p></p>
<p class="MsoNormal">kruntime of org.drools.reteoo.ReteooStatefulSession<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Similarly for the ReteooStatefulSession:<o:p></o:p></p>
<p class="MsoNormal">session of org.drools.impl.StatefulKnowledgeSessionImpl<o:p></o:p></p>
<p class="MsoNormal">session of org.drools.impl.StatefulKnowledgeSessionImpl<o:p></o:p></p>
<p class="MsoNormal">workingMemory of org.jbpm.process.instance.ProcessRuntimeImpl<o:p></o:p></p>
<p class="MsoNormal">workingMemory of org.jbpm.process.instance.ProcessRuntimeImpl<o:p></o:p></p>
<p class="MsoNormal">workingMemory of org.jbpm.process.instance.ProcessRuntimeImpl<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Is this a known issue? Am I missing anything in my code above.<o:p></o:p></p>
<p class="MsoNormal">I guess the alternative is to reuse my sessions – what is the most efficient way to remove all the facts from the working memory and get it back into a pristine state?<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Thanks,<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Thomas<o:p></o:p></p>
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