jack patwork created AMQ-6555:
---------------------------------
Summary: Failed to browse topic warnings caused by orphaned expire
message tasks in Sceduler
Key: AMQ-6555
URL: https://issues.apache.org/jira/browse/AMQ-6555
Project: ActiveMQ
Issue Type: Bug
Affects Versions: 5.14.1
Reporter: jack patwork
When using a FixedCountSubscriptionRecoveryPolicy on a topic I get millions of
warnings when the topic is gc'd after inactivity. The impact is that warn
logging has to be turned off which is not ideal. Looking in detail it seems
this is caused by a couple of things. Firstly the Topic start method can be
invoked twice, once when adding the destination to the RegionBroker and second
when the regionBroker is started.
That causes the same expireMessagesTask to get scheduled twice which reveals
the crux of the problem. The Scheduler allows the same task to be scheduled
again in new TimerTasks, even though it will use the same key and ophan any
existing (and running) TimerTasks. This is what's happening here. When the
topic gets stopped, the orphaned tasks continue to run causing these spurious
warnings that clog up the logs.
My suggestion would be for the scheduler to check if the task has already been
registered using a putIfAbsent and fail if it already exists:
https://github.com/apache/activemq/blob/d9350912984f12356e9d51b0f00b5a28f5cfa58d/activemq-client/src/main/java/org/apache/activemq/thread/Scheduler.java#L42
These are the warnings we see:
2017-01-10 11:36:13,885 [host] Scheduler] - WARN Topic
- Failed to browse Topic: myTopic
java.lang.NullPointerException
at
org.apache.activemq.broker.region.policy.FixedCountSubscriptionRecoveryPolicy.browse(FixedCountSubscriptionRecoveryPolicy.java:103)
at
org.apache.activemq.broker.region.policy.RetainedMessageSubscriptionRecoveryPolicy.browse(RetainedMessageSubscriptionRecoveryPolicy.java:111)
at org.apache.activemq.broker.region.Topic.doBrowse(Topic.java:677)
at org.apache.activemq.broker.region.Topic.access$1(Topic.java:639)
at org.apache.activemq.broker.region.Topic$2.run(Topic.java:791)
at
org.apache.activemq.thread.SchedulerTimerTask.run(SchedulerTimerTask.java:33)
at java.util.TimerThread.mainLoop(Timer.java:555)
at java.util.TimerThread.run(Timer.java:505
--
This message was sent by Atlassian JIRA
(v6.3.4#6332)
