#ActiveMq #Artemis – Fix phantom messages issue

Sometimes we end up with phantom messages in ActiveMq or Artemis engines.

This is usually the case when due to some network issue/ database issue and inconsistent commit was done.

I have no idea if this is a bug of the engine or a known case that can happen because of external causes.  

The issue with the “phantom messages” manifests like this. The counter associated with a queue has a diferent value than the actual number of messages from that queue.

The bellow example shows a case where the counter reported that amessage is still there but in fact the queue is empty. This is a problem when a client application is using the counter API call to estimate if all the queued message were processed.

List message reports no message:

[standalone@localhost:9992 /] /subsystem=messaging-activemq/server=default/jms-queue=myQueue:list-messages
{
    "outcome" => "success",
    "result" => []
}

Count message reports 1 message:

[standalone@localhost:9992 /] /subsystem=messaging-activemq/server=default/jms-queue=myQueue:count-messages
{
    "outcome" => "success",
    "result" => 1L
}

Solution:

Step 1:
Stop any consumer or producer applications. The easiest way is to simply undeploy the application.

[standalone@localhost:9992 /] /deployment=my_app.ear:undeploy
{
    "outcome" => "success",
    "result" => 1L
}

Step 2:

Reset the counter:

[standalone@localhost:9992 /] /subsystem=messaging-activemq/server=default/jms-queue=accountingSpace:reset-message-counter

Step 3:

Start consumer or producer applications

[standalone@localhost:9992 /] /deployment=my_app.ear:deploy
{
    "outcome" => "success",
    "result" => 1L
}

Interesting enough that there is an API call for counter reset. That means that the possibility of a corrupt counter is somehow accounted for in the API design.