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MQSeries.net Forum Index » WebSphere Message Broker (ACE) Support » Garbage Collection in WMB

Garbage Collection in WMB

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logonaniket

Posted: Thu Jan 28, 2016 7:26 am Post subject: Garbage Collection in WMB

Novice

Joined: 12 Dec 2013
Posts: 17

Hi Guys

I have been asked by my manager to study about Garbage Collection in WMB and come up with an analysis about memory leaks happening in the broker.

I found an article on the web which very nicely describes about GC in WMB: https://www.ibm.com/developerworks/community/blogs/aimsupport/entry/important_facts_about_garbage_collection_in_websphere_message_broker?lang=en

I was also able to execute this command:
mqsichangeproperties BK.T2 -e CONSUMER_EG -o ComIbmJVMManager -n jvmSystemProperty -v"-verbose:gc -Xverbosegclog:/var/mqsi/gc.trc"

It worked perfectly. But gc.trc which is an XML file is very difficult to understand... This is what it says:

Code:

<?xml version="1.0" ?>
<verbosegc version="20110519_AA">
<initialized>
   <attribute name="gcPolicy" value="-Xgcpolicy:optthruput" />
   <attribute name="maxHeapSize" value="0xe4e000" />
   <attribute name="initialHeapSize" value="0xe4e000" />
   <attribute name="compressedRefs" value="false" />
   <attribute name="pageSize" value="0x1000" />
   <attribute name="requestedPageSize" value="0x1000" />
</initialized>
<af type="tenured" id="1" timestamp="Jan 28 14:40:48 2016" intervalms="0.000">
   <minimum requested_bytes="56" />
   <time exclusiveaccessms="301.805" meanexclusiveaccessms="151.873" threads="1" lastthreadtid="0x000000001466C300" />
   <refs soft="114" weak="17" phantom="0" dynamicSoftReferenceThreshold="32" maxSoftReferenceThreshold="32" />
   <tenured freebytes="749568" totalbytes="14999552" percent="4" >
      <soa freebytes="0" totalbytes="14249984" percent="0" />
      <loa freebytes="749568" totalbytes="749568" percent="100" />
   </tenured>
   <gc type="global" id="1" totalid="1" intervalms="0.000">
      <classunloading classloaders="0" classes="0" timevmquiescems="0.000" timetakenms="0.152" />
      <finalization objectsqueued="16" />
      <timesms mark="15.386" sweep="0.400" compact="0.000" total="15.976" />
      <tenured freebytes="11771768" totalbytes="14999552" percent="78" >
         <soa freebytes="11022200" totalbytes="14249984" percent="77" />
         <loa freebytes="749568" totalbytes="749568" percent="100" />
      </tenured>
   </gc>
   <tenured freebytes="11770792" totalbytes="14999552" percent="78" >
      <soa freebytes="11021224" totalbytes="14249984" percent="77" />
      <loa freebytes="749568" totalbytes="749568" percent="100" />
   </tenured>
   <refs soft="114" weak="15" phantom="0" dynamicSoftReferenceThreshold="25" maxSoftReferenceThreshold="32" />
   <time totalms="317.840" />
</af>

Can someone explain me the XML or tell me a tool (I tried ISA but too confusing) which can upload this kind XML and tell us what is happening?

mqjeff

Posted: Thu Jan 28, 2016 8:24 am Post subject:

Grand Master

Joined: 25 Jun 2008
Posts: 17447

How have you determined that they are memory leaks, and not just a normal part of the WMB memory management process?

What issue is your manager trying to solve by having you alter the GC of an EG?
_________________
chmod -R ugo-wx /

joebuckeye

Posted: Thu Jan 28, 2016 9:25 am Post subject:

Partisan

Joined: 24 Aug 2007
Posts: 364
Location: Columbus, OH

Proper use of clearMessage() in JCN's cleared up our Java memory leaks. We didn't mess with GC at all.

PeterPotkay

Posted: Thu Jan 28, 2016 10:09 am Post subject:

Poobah

Joined: 15 May 2001
Posts: 7717

IBM Integration Bus and WebSphere Message Broker FAQ for Memory
http://www-01.ibm.com/support/docview.wss?uid=swg21665926&myns=swgws&mynp=OCSSNQK6&mynp=OCSSKM8N&mync=E
_________________
Peter Potkay
Keep Calm and MQ On

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