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From "Swapnonil Mukherjee (JIRA)" <>
Subject [jira] Commented: (AMQ-3103) Active MQ Queue stalls after the Job Scheduler component shuts down.
Date Fri, 24 Dec 2010 05:42:46 GMT


Swapnonil Mukherjee commented on AMQ-3103:

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. 

> Active MQ Queue stalls after the Job Scheduler component shuts down.
> --------------------------------------------------------------------
>                 Key: AMQ-3103
>                 URL:
>             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.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
> 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 |
| JobScheduler:JMS
> java.lang.NullPointerException
>         at org.apache.kahadb.index.BTreeIndex.loadNode(
>         at org.apache.kahadb.index.BTreeNode.getChild(
>         at org.apache.kahadb.index.BTreeNode.remove(
>         at org.apache.kahadb.index.BTreeIndex.remove(
>         at
>         at$4.execute(
>         at
>         at
>         at
>         at
>         at
> 2010-12-10 16:31:39,561 | INFO  | JobSchedulerStore:activemq-data/primary/scheduler stopped
| | 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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