Re: NullPointerException when using shared cache

Mon, 25 Sep 2006 07:09:20 -0700 

Thanks Bryan! This is certainly helpful.

Andrus

On Sep 25, 2006, at 10:05 AM, Bryan Lewis wrote:

Okay, I installed the patched jar on our production servers.  It'll be
difficult to say for sure that the problem was fixed, seeing as how it
happened to us only once this year.  The absence of a report from me
will mean that things at least didn't get any worse. :-)


Andrus Adamchik wrote:

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>[EMAIL PROTECTED] {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>[EMAIL PROTECTED] {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>
[EMAIL PROTECTED] {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 [email protected] as a bug.

java.lang.IllegalStateException: Entry.next=null,
data[removeIndex]=<ObjectId:Customer,
id=534080>[EMAIL PROTECTED] {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>[EMAIL PROTECTED] {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>
[EMAIL PROTECTED] {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 [email protected] 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.snapshotsUpdatedForObjec ts(ObjectStore.java:559) 


        at
org.objectstyle.cayenne.access.ObjectResolver.objectsFromDataRows (ObjectResolver.java:162) 


        at
org.objectstyle.cayenne.access.ObjectResolver.synchronizedObjectsFr omDataRows(ObjectResolver.java:137) 


        at
org.objectstyle.cayenne.access.DataDomainQueryAction.interceptObjec tConversion(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.snapshotsUpdatedForObje cts(DataRowStore.java:313) 


        at
org.objectstyle.cayenne.access.ObjectResolver.objectsFromDataRows (ObjectResolver.java:159) 


        at
org.objectstyle.cayenne.access.ObjectResolver.synchronizedObjectsFr omDataRows(ObjectResolver.java:134) 


        at
org.objectstyle.cayenne.access.DataDomainQueryAction.interceptObjec tConversion(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



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