ConnectionDotFileInterceptor not thread safe.

• Key: AMQ-749
• Type: Bug
• Status: Resolved
• Resolution: Fixed
• Priority: Critical
• Assignee: Hiram Chirino
• Reporter: Ning Li
• Affects Version/s: 4.0
• Fix Version/s: 4.1.0, 4.0.1

Description

Unable to run multithreaded MQ application, even for the simplest case.

This is the peudo code, modified the ProducerTool.java

For ( thread 1 to 30 )
{
Connection connection = createConnection();
Session session = createSession(connection);
Producer producer = createProducer(session);
sendMessages(producer, 20); //send 20 messages to broker using all default settings
}

these are the exceptions from broker:
Caught: javax.jms.JMSException: java.util.ConcurrentModificationException
[cp://localhost/127.0.0.1:61616] ActiveMQConnection WARN Async exception with no exception listener: java.util.ConcurrentModificationException
java.util.ConcurrentModificationException
at java.util.HashMap$HashIterator.nextEntry(HashMap.java:787)
at java.util.HashMap$EntryIterator.next(HashMap.java:829)
at java.util.HashMap$EntryIterator.next(HashMap.java:827)
at org.apache.activemq.broker.view.ConnectionDotFileInterceptor.printProducers(ConnectionDotFileInterceptor.java:157)
at org.apache.activemq.broker.view.ConnectionDotFileInterceptor.generateFile(ConnectionDotFileInterceptor.java:140)
at org.apache.activemq.broker.view.DotFileInterceptorSupport.generateFile(DotFileInterceptorSupport.java:47)
at org.apache.activemq.broker.view.ConnectionDotFileInterceptor.addProducer(ConnectionDotFileInterceptor.java:85)
at org.apache.activemq.broker.MutableBrokerFilter.addProducer(MutableBrokerFilter.java:90)
at org.apache.activemq.broker.AbstractConnection.processAddProducer(AbstractConnection.java:397)
at org.apache.activemq.command.ProducerInfo.visit(ProducerInfo.java:100)
at org.apache.activemq.broker.AbstractConnection.service(AbstractConnection.java:201)
at org.apache.activemq.broker.TransportConnection$1.onCommand(TransportConnection.java:62)
at org.apache.activemq.transport.ResponseCorrelator.onCommand(ResponseCorrelator.java:97)
at org.apache.activemq.transport.TransportFilter.onCommand(TransportFilter.java:63)
at org.apache.activemq.transport.WireFormatNegotiator.onCommand(WireFormatNegotiator.java:114)
at org.apache.activemq.transport.InactivityMonitor.onCommand(InactivityMonitor.java:122)
at org.apache.activemq.transport.TransportSupport.doConsume(TransportSupport.java:87)
at org.apache.activemq.transport.tcp.TcpTransport.run(TcpTransport.java:143)
at java.lang.Thread.run(Thread.java:595)

and exception in the client side:
javax.jms.JMSException: java.util.ConcurrentModificationException
at org.apache.activemq.util.JMSExceptionSupport.create(JMSExceptionSupport.java:45)
at org.apache.activemq.ActiveMQConnection.syncSendPacket(ActiveMQConnection.java:1137)
at org.apache.activemq.AdvisoryConsumer.<init>(AdvisoryConsumer.java:45)
at org.apache.activemq.ActiveMQConnection.ensureConnectionInfoSent(ActiveMQConnection.java:1227)
at org.apache.activemq.ActiveMQConnection.start(ActiveMQConnection.java:435)
at com.businessobjects.framework.services.mq.ToolSupport.createConnection(ToolSupport.java:51)
at com.businessobjects.framework.services.mq.ProducerTool.run(ProducerTool.java:106)

Comments

[Hiram Chirino]

As a simple workaround, disable the dot file broker plugin.

[Hiram Chirino]

Added synchronization to make thread safe.