[Beginner's Corner] - Re: Singletons in a J2EE application server
by Bernd Eckenfels
Bernd Eckenfels [http://community.jboss.org/people/b.eckenfels] created the discussion
"Re: Singletons in a J2EE application server"
To view the discussion, visit: http://community.jboss.org/message/627987#627987
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According to the Java EE 6 and EJB 3.1 Specification a Stateless Session Bean with the @Singleton Annotation is created once for an Application. If the Application is deployed on multiple VMs (in a Cluster) you have one Instance for each VM.
Of courxe you can have multiple different Singleton Beans.
If the locking and processing of a singleton bean is a problem for application performance, it could make sense to have multiple. But strictly speaking you wont have a real singleton anymore. This would be more like Statefull Session Beans. It is not addressed by the spec, but you could implement it conformant with the Spec by having multiple Singletons (same class, different name). In that case you would have to care for pooling andsynchronizing yourself.
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13 years, 3 months
[Beginner's Corner] - Jboss Clusters
by Hari Ganesh
Hari Ganesh [http://community.jboss.org/people/hariganesh] created the discussion
"Jboss Clusters"
To view the discussion, visit: http://community.jboss.org/message/621584#621584
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Hi All,
I am a System Admin and a newbie to Jboss. But unfortunately,i am in charge of managing a Jboss Cluster.
I am managing a Two node cluster in a corporate environment and i find that when i start up JBOSS, the number of Members in cluster is shown as 4 as seen in below log, although i am managing only two nodes (16.181.233.127 & 16.181.233.128):
I don't know why my Jboss server is binding with other all Jboss servers in my network. Attaching the full server.log herewith. Not sure whether this is the normal scenario.
I request your help in resolving this. Request replies to be a little explanatory.
Thanks in advance.
HG
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GMS: address is 16.181.233.127:53312
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2011-08-17 15:44:13,913 DEBUG [org.jboss.ha.framework.interfaces.HAPartition.DefaultPartition] ViewAccepted: initial members set
2011-08-17 15:44:13,916 DEBUG [org.jboss.ha.framework.server.ClusterPartition] Starting channel
2011-08-17 15:44:13,916 DEBUG [org.jboss.ha.framework.interfaces.HAPartition.DefaultPartition] get nodeName
2011-08-17 15:44:13,917 DEBUG [org.jboss.ha.framework.interfaces.HAPartition.DefaultPartition] Get current members
2011-08-17 15:44:13,917 INFO [org.jboss.ha.framework.interfaces.HAPartition.DefaultPartition] Number of cluster members: 4
2011-08-17 15:44:15,371 INFO [org.jboss.cache.TreeCache] viewAccepted(): [16.181.233.119:20259|648] [16.181.233.119:20259, 16.181.237.202:46037 , 16.181.233.128:42572, 16.181.233.127:34248]
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13 years, 3 months
[jBPM] - Help wanted debugging jbpm 3.3
by oxbow_lakes
oxbow_lakes [http://community.jboss.org/people/oxbow_lakes] created the discussion
"Help wanted debugging jbpm 3.3"
To view the discussion, visit: http://community.jboss.org/message/627946#627946
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I find myself supporting an application which I didn't write and which makes heavy use of JBPM 3.3. Occasionally it starts spewing exceptions non-stop
java.lang.NullPointerException
at org.jbpm.graph.def.GraphElement.getRuntimeActionsForEvent(GraphElement.java:310)
at org.jbpm.graph.def.GraphElement.fireAndPropagateEvent(GraphElement.java:217)
at sun.reflect.GeneratedMethodAccessor55.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:601)
at org.hibernate.proxy.pojo.cglib.CGLIBLazyInitializer.invoke(CGLIBLazyInitializer.java:157)
at org.jbpm.taskmgmt.def.Task$$EnhancerByCGLIB$$8cd382f6.fireAndPropagateEvent(<generated>)
at org.jbpm.job.Timer.execute(Timer.java:51)
at sun.reflect.GeneratedMethodAccessor53.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:601)
at org.hibernate.proxy.pojo.cglib.CGLIBLazyInitializer.invoke(CGLIBLazyInitializer.java:157)
at org.jbpm.job.Job$$EnhancerByCGLIB$$7ab55e8c.execute(<generated>)
at be.jorambarrez.jbpm3_spring_integration.FixExceptionLengthJobExecutorThread.executeJob(FixExceptionLengthJobExecutorThread.java:164)
at be.jorambarrez.jbpm3_spring_integration.SpringJobExecutorThread.access$101(SpringJobExecutorThread.java:24)
at be.jorambarrez.jbpm3_spring_integration.SpringJobExecutorThread$2.doInTransactionWithoutResult(SpringJobExecutorThread.java:64)
at org.springframework.transaction.support.TransactionCallbackWithoutResult.doInTransaction(TransactionCallbackWithoutResult.java:33)
at org.springframework.transaction.support.TransactionTemplate.execute(TransactionTemplate.java:128)
at be.jorambarrez.jbpm3_spring_integration.SpringJobExecutorThread.executeJob(SpringJobExecutorThread.java:59)
I have no source code for the GraphElement, don't know where to find it and there is not a single class in there from my application. I don't know where to start trying to get to the bottom of this. Any help greatly appreciated - is this a bug in JBPM? Was it fixed in a different version? Can anyone point me to a workaround?
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13 years, 3 months