Details
Major Description
We just migrated from ActiveMQ 5.4.2 to ActiveMQ 5.5.0. So far so good, with one exception (pun not intended). In one case where we have an embedded broker, we're seeing this exception get logged on occasion:
WARNING; 08-Apr-2011 11:11:41; tid:45931; TransportConnection stopAsync; cannot create async transport stopper thread.. not waiting for stop to complete, reason:
java.util.ConcurrentModificationException
at java.util.HashMap$HashIterator.nextEntry(HashMap.java:793)
at java.util.HashMap$EntryIterator.next(HashMap.java:834)
at java.util.HashMap$EntryIterator.next(HashMap.java:832)
at java.util.HashMap.putAllForCreate(HashMap.java:435)
at java.util.HashMap.<init>(HashMap.java:225)
at org.slf4j.helpers.BasicMDCAdapter.getCopyOfContextMap(BasicMDCAdapter.java:130)
at org.slf4j.MDC.getCopyOfContextMap(MDC.java:182)
at org.apache.activemq.util.MDCHelper.getCopyOfContextMap(MDCHelper.java:30)
at org.apache.activemq.broker.TransportConnection.stopAsync(TransportConnection.java:946)
at org.apache.activemq.broker.TransportConnection.processShutdown(TransportConnection.java:353)
at org.apache.activemq.command.ShutdownInfo.visit(ShutdownInfo.java:35)
at org.apache.activemq.broker.TransportConnection.service(TransportConnection.java:306)
at org.apache.activemq.broker.TransportConnection$1.onCommand(TransportConnection.java:179)
at org.apache.activemq.transport.ResponseCorrelator.onCommand(ResponseCorrelator.java:116)
at org.apache.activemq.transport.TransportFilter.onCommand(TransportFilter.java:69)
at org.apache.activemq.transport.vm.VMTransport.iterate(VMTransport.java:218)
at org.apache.activemq.thread.PooledTaskRunner.runTask(PooledTaskRunner.java:127)
at org.apache.activemq.thread.PooledTaskRunner$1.run(PooledTaskRunner.java:48)
at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908)
at java.lang.Thread.run(Thread.java:662)
Up until this morning, I had only seen that logged during shutdown of the app context. But just now, it popped out independently, out of the blue.
For what it's worth, here's the app context config:
<broker xmlns="http://activemq.apache.org/schema/core"
id="embeddedActivemqBroker"
useJmx="true"
persistent="true"
schedulerSupport="false"
advisorySupport="false"
enableStatistics="true">
<destinationPolicy>
<policyMap>
<policyEntries>
<policyEntry queue=">" producerFlowControl="false" memoryLimit="20mb"/>
</policyEntries>
</policyMap>
</destinationPolicy>
<persistenceAdapter>
<kahaDB directory="${EmbeddedBroker.dataDirectory}"
concurrentStoreAndDispatchQueues="false"/>
</persistenceAdapter>
</broker>
Has anybody else seen this ConcurrentModificationException happening with 5.5.0 (or otherwise)? Any ideas?
I suppose I should also mention that we're using slf4j 1.6.1. Not sure if that has anything to do with this, since the stack trace does show it happening in slf4j land...
<dependency>
<groupId>org.slf4j</groupId>
<artifactId>slf4j-api</artifactId>
<version>1.6.1</version>
<scope>runtime</scope>
</dependency>
<dependency>
<groupId>org.slf4j</groupId>
<artifactId>slf4j-jdk14</artifactId>
<version>1.6.1</version>
<scope>runtime</scope>
</dependency>