Re: NullPointerException when using shared cache

From: Andrus Adamchik (andru..bjectstyle.org)
Date: Sun Sep 24 2006 - 20:32:29 EDT

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    Ayhan, Wolfgang and others who have this synchronization issue - I
    posted a patched version of 1.2.1 Cayenne:

    http://dev.objectstyle.org/~andrus/cayenne-1.2.1-CAY-565-patched.tar.gz

    I would appreciate very much if you could test it in your environment
    and let me know whether it fixes the problem. I posted more comments
    and the exact patches that were applies on Jira:

    http://issues.apache.org/cayenne/browse/CAY-565

    Thanks
    Andrus

    On Sep 12, 2006, at 9:35 AM, Andrus Adamchik wrote:

    > CAY-565 was closed as "Can not reproduce", so there was no fix. I
    > reopened this issue, bumping the priority to "Critical". I will add
    > synchronization, even though I can't test it.
    >
    > Andrus
    >
    >
    > On Sep 12, 2006, at 5:51 AM, Ayhan Kondoz wrote:
    >> Hello,
    >>
    >>
    >>
    >> I am getting NullPointerExceptions when I am trying to use the
    >> shared caching feature of cayenne.
    >>
    >>
    >>
    >> I have 3 servers. Each server has it's own tomcat / axis
    >> webservice and I have an avarage access of about 4 - 5 connections
    >> per second. Each connection results in about 3 - 4 select queries
    >> and about 20% of the connections result in an additional 2 - 3
    >> insert / update queries. So the servers are working at pretty
    >> heavy load.
    >>
    >>
    >>
    >> Yesterday I implemented the usage of cayenne's (remote) shared
    >> caching feature using JavaGroups and at first everything seemed to
    >> work just fine. But after about 1 hour, one of the servers started
    >> to produce NullPointerExceptions on every connection. i found this
    >> bug ( http://issues.apache.org/cayenne/browse/CAY-565 ) which
    >> seems to address my problem but the status is resolved?!
    >>
    >>
    >>
    >> i tried cayenne 1.2 and 1.2B1 and in both cases got this
    >> exceptions but only if shared caching is activated. When I
    >> deactivate caching everything seems to work fine again.
    >>
    >> It seems that there is a problem with the syncronization. This
    >> error occursed when under heavy load and a lot of threads are
    >> active at the same time. But if it is really a syncronization
    >> problem the same error could occure on every system (even if much
    >> more unlikely) even if not under heavy load.
    >>
    >>
    >>
    >> Cheers
    >>
    >> Ayhan Kondoz
    >>
    >>
    >>
    >>
    >>
    >> The exception when using common-collections 3.2
    >>
    >>
    >>
    >> [11.09.06 21:30:32] (ERROR): Entry.next=null, data[removeIndex]
    >> =<ObjectId:Customer,
    >> id=534080>=org.objectstyle.cayenne.DataRo..da158[values=
    >> {suspended=false, login=christian.hantke1, rec_create=Tue May 02
    >> 00:00:00 CEST 2006, rec_change=Tue May 02 20:18:34 CEST 2006,
    >> last_updated=Mon Sep 11 21:28:26 CEST 2006, cid=709779451,
    >> id=534080, mandant_id=3}, version=-9223372036854422785,
    >> replaces=-9223372036854775808] previous=<ObjectId:Customer,
    >> d=534080>=org.objectstyle.cayenne.DataRo..da158[values=
    >> {suspended=false, login=christian.hantke1, rec_create=Tue May 02
    >> 00:00:00 CEST 2006, rec_change=Tue May 02 20:18:34 CEST 2006,
    >> last_updated=Mon Sep 11 21:28:26 CEST 2006, cid=709779451,
    >> id=534080, mandant_id=3}, version=-9223372036854422785,
    >> replaces=-9223372036854775808] key=<Ob
    >>
    >> jectId:Customer, id=364956>
    >> value=org.objectstyle.cayenne.DataRo..26844[values=
    >> {suspended=false, login=nadda89, rec_create=Thu Mar 30 00:00:00
    >> CEST 2006, rec_change=Thu Mar 30 22:19:00 CEST 2006,
    >> last_updated=Fri Aug 04 16:09:35 CEST 2006, cid=705229711,
    >> id=364956, mandant_id=3}, version=-9223372036854407476,
    >> replaces=-9223372036854775808] size=10000 maxSize=10000 Please
    >> check that your keys are immutable, and that you have used
    >> synchronization properly. If so, then please report this to
    >> commons-de..akarta.apache.org as a bug.
    >>
    >> java.lang.IllegalStateException: Entry.next=null, data[removeIndex]
    >> =<ObjectId:Customer,
    >> id=534080>=org.objectstyle.cayenne.DataRo..da158[values=
    >> {suspended=false, login=christian.hantke1, rec_create=Tue May 02
    >> 00:00:00 CEST 2006, rec_change=Tue May 02 20:18:34 CEST 2006,
    >> last_updated=Mon Sep 11 21:28:26 CEST 2006, cid=709779451,
    >> id=534080, mandant_id=3}, version=-9223372036854422785,
    >> replaces=-9223372036854775808] previous=<ObjectId:Customer,
    >> id=534080>=org.objectstyle.cayenne.DataRo..da158[values=
    >> {suspended=false, login=christian.hantke1, rec_create=Tue May 02
    >> 00:00:00 CEST 20 06, rec_change=Tue May 02 20:18:34 CEST 2006,
    >> last_updated=Mon Sep 11 21:28:26 CEST 2006, cid=709779451,
    >> id=534080, mandant_id=3}, version=-9223372036854422785,
    >> replaces=-9223372036854775808] key=<ObjectId:Customer, id=364956>
    >> value=org.objectstyle.cayenne.DataRo..26844[values=
    >> {suspended=false, login=nadda89, rec_create=Thu Mar 30 00:00:00
    >> CEST 2006, rec_change=Thu Mar 30 22:19:00 CEST 2006,
    >> last_updated=Fri Aug 04 16:09:35 CEST 2006, cid=705229711,
    >> id=364956, mandant_id=3}, version=-9223372036854407476,
    >> replaces=-9223372036854775808] size=10000 maxSize=10000 Please
    >> check that your keys are immutable, and that you have used
    >> synchronization properly. If so, then please report this to
    >> commons-de..akarta.apache.org as a bug.
    >>
    >> at org.apache.commons.collections.map.LRUMap.reuseMapping
    >> (LRUMap.java:300)
    >>
    >> at org.apache.commons.collections.map.LRUMap.addMapping
    >> (LRUMap.java:266)
    >>
    >> at org.apache.commons.collections.map.AbstractHashedMap.put
    >> (AbstractHashedMap.java:283)
    >>
    >> at
    >> org.objectstyle.cayenne.access.DataRowStore.processUpdatedSnapshots
    >> (DataRowStore.java:537)
    >>
    >> at
    >> org.objectstyle.cayenne.access.DataRowStore.processSnapshotChanges
    >> (DataRowStore.java:496)
    >>
    >> at
    >> org.objectstyle.cayenne.access.ObjectStore.snapshotsUpdatedForObjects
    >> (ObjectStore.java:559)
    >>
    >> at
    >> org.objectstyle.cayenne.access.ObjectResolver.objectsFromDataRows
    >> (ObjectResolver.java:162)
    >>
    >> at
    >> org.objectstyle.cayenne.access.ObjectResolver.synchronizedObjectsFrom
    >> DataRows(ObjectResolver.java:137)
    >>
    >> at
    >> org.objectstyle.cayenne.access.DataDomainQueryAction.interceptObjectC
    >> onversion(DataDomainQueryAction.java:363)
    >>
    >> at
    >> org.objectstyle.cayenne.access.DataDomainQueryAction.execute
    >> (DataDomainQueryAction.java:151)
    >>
    >> at org.objectstyle.cayenne.access.DataDomain.onQuery
    >> (DataDomain.java:715)
    >>
    >> at
    >> org.objectstyle.cayenne.util.ObjectContextQueryAction.runQuery
    >> (ObjectContextQueryAction.java:249)
    >>
    >> at
    >> org.objectstyle.cayenne.access.DataContextQueryAction.execute
    >> (DataContextQueryAction.java:90)
    >>
    >> at org.objectstyle.cayenne.access.DataContext.onQuery
    >> (DataContext.java:1320)
    >>
    >> at org.objectstyle.cayenne.access.DataContext.performQuery
    >> (DataContext.java:1309)
    >>
    >>
    >>
    >> The exception when using common-collections 3.1
    >>
    >>
    >>
    >> [11.09.06 15:29:13] (ERROR):
    >>
    >> java.lang.NullPointerException
    >>
    >> at org.apache.commons.collections.map.LRUMap.reuseMapping
    >> (LRUMap.java:272)
    >>
    >> at org.apache.commons.collections.map.LRUMap.addMapping
    >> (LRUMap.java:243)
    >>
    >> at org.apache.commons.collections.map.AbstractHashedMap.put
    >> (AbstractHashedMap.java:282)
    >>
    >> at
    >> org.objectstyle.cayenne.access.DataRowStore.processUpdatedSnapshots
    >> (DataRowStore.java:612)
    >>
    >> at
    >> org.objectstyle.cayenne.access.DataRowStore.processSnapshotChanges
    >> (DataRowStore.java:571)
    >>
    >> at
    >> org.objectstyle.cayenne.access.DataRowStore.snapshotsUpdatedForObject
    >> s(DataRowStore.java:313)
    >>
    >> at
    >> org.objectstyle.cayenne.access.ObjectResolver.objectsFromDataRows
    >> (ObjectResolver.java:159)
    >>
    >> at
    >> org.objectstyle.cayenne.access.ObjectResolver.synchronizedObjectsFrom
    >> DataRows(ObjectResolver.java:134)
    >>
    >> at
    >> org.objectstyle.cayenne.access.DataDomainQueryAction.interceptObjectC
    >> onversion(DataDomainQueryAction.java:373)
    >>
    >> at
    >> org.objectstyle.cayenne.access.DataDomainQueryAction.execute
    >> (DataDomainQueryAction.java:151)
    >>
    >> at org.objectstyle.cayenne.access.DataDomain.onQuery
    >> (DataDomain.java:766)
    >>
    >> at
    >> org.objectstyle.cayenne.util.ObjectContextQueryAction.runQuery
    >> (ObjectContextQueryAction.java:253)
    >>
    >> at
    >> org.objectstyle.cayenne.access.DataContextQueryAction.execute
    >> (DataContextQueryAction.java:90)
    >>
    >> at org.objectstyle.cayenne.access.DataContext.onQuery
    >> (DataContext.java:1422)
    >>
    >> at org.objectstyle.cayenne.access.DataContext.performQuery
    >> (DataContext.java:1411)
    >>
    >>
    >>
    >>
    >>
    >>
    >>
    >> Ayhan Kondoz
    >>
    >>
    >>
    >> Software-Entwicklung
    >>
    >>
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