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https://issues.apache.org/jira/browse/AMQ-3103?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12974842#action_12974842
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Swapnonil Mukherjee edited comment on AMQ-3103 at 12/24/10 12:48 AM:
---------------------------------------------------------------------

Hi Everybody,

Another observation. This is one is funny.

We are observing that the Job Scheduler component *shuts down everyday 
precisely at 01:48 hours GMT.*
As mentioned earlier, the way we recover from these failures is by
* Stopping the broker using $> ./activemq stop
* Deleting the db.redo file from the kahadb directory
* Restarting the broker using $> ./activemq start

Are we missing doing something for the recovery?

I am re-attaching another log file named activemq-1.log. This one is from our 
staging servers where you would observe that the Job Scheduler shuts itself 
precisely at 01:48 hours.


      was (Author: swapnonil):
    Hi Everybody,

Another observation. This is one is funny.

We are observing that the Job Scheduler component *shuts down everyday 
precisely at 01:48 hours GMT.*
As mentioned earlier, the way we recover from these failures is by
* Stopping the broker using $> ./activemq stop
* Deleting the db.redo file from the kahadb directory
* Restarting the broker using $> ./activemq start

Are we missing doing something for the recovery?

I am re-attaching another activemq.log file. This one is from our staging 
servers. 

  
> Queue stalls after Job Scheduler component shuts down.
> ------------------------------------------------------
>
>                 Key: AMQ-3103
>                 URL: https://issues.apache.org/jira/browse/AMQ-3103
>             Project: ActiveMQ
>          Issue Type: Bug
>          Components: Broker
>    Affects Versions: 5.4.2
>         Environment: Redhat Enterprise Linux 5.X, 
> JDK 1.5 32-bit
> JDK 1.6 64-bit
>            Reporter: Swapnonil Mukherjee
>         Attachments: activemq-1.log, activemq.log, activemq.xml
>
>
> Observation
> ----
> Active MQ stops accepting all incoming messages destined for a particular 
> queue, after the scheduler component processing scheduled messages on that 
> queue encounters an Null Pointer Exception.
> Environment
> ----
> We are using the Spring JMSTemplate component to post messages onto a queue. 
> We also place a delay of 30 seconds on each message before posting
> {noformat}
> message.setLongProperty(ScheduledMessage.AMQ_SCHEDULED_DELAY, 
> Integer.parseInt("30") * 1000);
> {noformat}
> We use the Spring Default Message Listener Container to receive messages.
> Normally the broker runs fine and we have seen messages appear under the 
> "Scheduled" tab on the Active MQ Console, after which they processed normally 
> and we can tally using the "Messages Enqueued" and  the "Messages Dequeued" 
> numbers. But occasionally the Job Scheduler fails with the following 
> exception.
> {code:xml}
> 2010-12-10 16:31:38,522 | ERROR | JMS Failed to schedule job | 
> org.apache.activemq.broker.scheduler.JobSchedulerImpl | JobScheduler:JMS
> java.lang.NullPointerException
>         at org.apache.kahadb.index.BTreeIndex.loadNode(BTreeIndex.java:264)
>         at org.apache.kahadb.index.BTreeNode.getChild(BTreeNode.java:225)
>         at org.apache.kahadb.index.BTreeNode.remove(BTreeNode.java:330)
>         at org.apache.kahadb.index.BTreeIndex.remove(BTreeIndex.java:194)
>         at 
> org.apache.activemq.broker.scheduler.JobSchedulerImpl.remove(JobSchedulerImpl.java:347)
>         at 
> org.apache.activemq.broker.scheduler.JobSchedulerImpl$4.execute(JobSchedulerImpl.java:125)
>         at org.apache.kahadb.page.Transaction.execute(Transaction.java:728)
>         at 
> org.apache.activemq.broker.scheduler.JobSchedulerImpl.remove(JobSchedulerImpl.java:123)
>         at 
> org.apache.activemq.broker.scheduler.JobSchedulerImpl.mainLoop(JobSchedulerImpl.java:515)
>         at 
> org.apache.activemq.broker.scheduler.JobSchedulerImpl.run(JobSchedulerImpl.java:429)
>         at java.lang.Thread.run(Thread.java:619)
> 2010-12-10 16:31:39,561 | INFO  | 
> JobSchedulerStore:activemq-data/primary/scheduler stopped | 
> org.apache.activemq.broker.scheduler.JobSchedulerStore | JobScheduler:JMS
> {code}
> Why does the Job Scheduler fail? One possible reason we have found is that 
> the clock time settings on the VMs producing the messages and the broker as 
> well as the consumers are all different. So the Job Scheduler may be shutting 
> itself down arbitrarily due to this difference in clock. We are in the 
> process of syncing all clocks but we are not sure whether this will solve the 
> problem.
> Bug
> ----
> But the Bug really is, even if the Job Scheduler encounters an Null Pointer, 
> why should it shutdown? Even more problematic is the fact that the queue 
> itself stalls and does not accept anymore messages after the Job Scheduler 
> shuts down.
> We have tried to delete the db.redo log to recover from this type of 
> shutdown. The broker recovers fine, but all messages posted to this queue 
> after the Job Scheduler shut itself down were lost. We have not been able to 
> recover those messages.
> I am attaching the activemq log and activemq configuration file.

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