WebLogic MemorySessionContext

We had some PROD OutOfMemory recently.... done a heap dump and seen that we were in this situation: http://xmlandmore.blogspot.ch/2013/03/analyzing-performance-issue-caused-by.html

One instance of "weblogic.servlet.internal.session.MemorySessionContext" loaded by "sun.misc.Launcher$AppClassLoader @ 0x7818fbb60" occupies 732'427'648 (82.97%) bytes. The memory is accumulated in one instance of "java.util.Hashtable$Entry[]" loaded by "".

Keywords
weblogic.servlet.internal.session.MemorySessionContext
java.util.Hashtable$Entry[]
sun.misc.Launcher$AppClassLoader @ 0x7818fbb60

and this is the "Shortest Paths to the Accumulation Point" in Eclipse MAT:

java.util.Hashtable$Entry[383] @ 0x7b0455fd8
 1'552 732'427'400 
\table java.util.Hashtable @ 0x7823d6118
 48 732'427'488 
.\openSessions weblogic.servlet.internal.session.MemorySessionContext @ 0x7823d60e8
 48 732'427'648 
..+sessionContext weblogic.servlet.internal.WebAppServletContext @ 0x782310e88
 208 452'632 
..|+[0] java.lang.Object[1] @ 0x7812d7e28
 24 24 
..||\array java.util.concurrent.CopyOnWriteArrayList @ 0x7812d7de0
 24 96 
..||.\initializedContexts com.sun.faces.config.ConfigManager @ 0x7812d7dd0
 16 112 
..||..\CONFIG_MANAGER class com.sun.faces.config.ConfigManager @ 0x776ab8198
 64 100'560 
..||...\[17] java.lang.Object[2560] @ 0x78235eb90
 10'256 10'256 
..||....\elementData java.util.Vector @ 0x78235ae78
 32 10'288 
..||.....\classes weblogic.utils.classloaders.ChangeAwareClassLoader @ 0x78233c758
 104 9'648'032 
..||......+contextClassLoader com.iona.corba.art.workqueue.AutomaticWorkQueueThreadPool$WorkQueueThread @ 0x783f0a9f0 [ORB=_it_orb_id_1,Pool=1]::id-10 Thread
 120 2'184 
..||......+contextClassLoader com.iona.corba.art.workqueue.AutomaticWorkQueueThreadPool$WorkQueueThread @ 0x783f0b2d8 [ORB=_it_orb_id_1,Pool=1]::id-9 Thread
 120 2'184 
..||......+contextClassLoader com.iona.corba.art.workqueue.AutomaticWorkQueueThreadPool$WorkQueueThread @ 0x783f0bb60 [ORB=_it_orb_id_1,Pool=1]::id-8 Thread
 120 2'192 
..||......+contextClassLoader com.iona.corba.art.workqueue.AutomaticWorkQueueThreadPool$WorkQueueThread @ 0x783f12410 [ORB=_it_orb_id_1,Pool=1]::id-7 Thread
 120 2'192 
..||......+contextClassLoader com.iona.corba.art.workqueue.AutomaticWorkQueueThreadPool$WorkQueueThread @ 0x783f12cd8 [ORB=_it_orb_id_1,Pool=1]::id-6 Thread
 120 2'192 
..||......+contextClassLoader com.iona.corba.art.workqueue.AutomaticWorkQueueThreadPool$WorkQueueThread @ 0x783f13560 [ORB=_it_orb_id_1,Pool=1]::id-5 Thread
 120 2'304 
..||......+contextClassLoader com.iona.corba.art.workqueue.AutomaticWorkQueueThreadPool$WorkQueueThread @ 0x783f13e60 [ORB=_it_orb_id_1,Pool=1]::id-4 Thread
 120 2'232 
..||......+contextClassLoader com.iona.corba.art.workqueue.AutomaticWorkQueueThreadPool$WorkQueueThread @ 0x783f1a680 [ORB=_it_orb_id_1,Pool=1]::id-3 Thread
 120 2'160 
..||......+contextClassLoader com.iona.corba.art.workqueue.AutomaticWorkQueueThreadPool$WorkQueueThread @ 0x783f1aef0 [ORB=_it_orb_id_1,Pool=1]::id-2 Thread
 120 2'304 
..||......+contextClassLoader com.iona.corba.art.workqueue.AutomaticWorkQueueThreadPool$WorkQueueThread @ 0x783f1b7a0 [ORB=_it_orb_id_1,Pool=1]::id-1 Thread
 120 2'304 
..||......+contextClassLoader java.lang.Thread @ 0x7da0b6650 Keep-Alive-Timer »
 112 176 
..||......+classloader java.security.ProtectionDomain @ 0x78235b0b0 »
 40 232 
..||......\Total: 12 entries
   
..|+context weblogic.servlet.internal.WebAppRuntimeMBeanImpl @ 0x7824209f8 »
 

It turned out indeed that the session timeout was indeed waaay too long...