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From "Luca Zenti (Created) (JIRA)" <j...@apache.org>
Subject [jira] [Created] (AMQ-3593) Messages with empty marshalledProperties
Date Mon, 14 Nov 2011 19:06:51 GMT
Messages with empty marshalledProperties
----------------------------------------

                 Key: AMQ-3593
                 URL: https://issues.apache.org/jira/browse/AMQ-3593
             Project: ActiveMQ
          Issue Type: Bug
    Affects Versions: 5.5.1, 5.4.2
         Environment: * OS: Linux version 2.6.9-67.0.4.ELlargesmp (brewbuilder@hs20-bc1-6.build.redhat.com)
(gcc version 3.4.6 20060404 (Red Hat 3.4.6-9)) #1 SMP Fri Jan 18 05:10:01 EST 2008

* JVM (-server option in use): Java(TM) SE Runtime Environment (build 1.6.0_24-b07) Java HotSpot(TM)
Server VM (build 19.1-b02, mixed mode)


            Reporter: Luca Zenti


Sometimes messages arrive on the client with an empty "marshalledProperties" field. This causes
an exception trying to unmarshall them.
This happens very rarely, but we've got at least 2-3 cases a day per subscriber in our production
environment.
We use a broker embedded with a server component that publishes messages on topics. The subscribers
are remote.
I was unable to replicate the problem on my Windows workstation, nor to reproduce it precisely.

Attached you can find a simple pair of programs (the publisher and the subscriber) that can
reproduce the issue within 5 minutes at most on my environment. This happens only if at least
one of the subscribers runs on a remote machine and it seems to happen quickly with more clients
connected.
The publishing program has a command line arguments that allows to adjust the publishing rate,
in my case with 10,000 messages per second and 2 clients the problem happens within a couple
of minutes.

I also found a workaround for this problem: as far as I can understand, my original message
is copied as a Java object to the broker (the broker is embedded, so there is no need to serialize
it), then it is copied using its copy method to one or more new ActiveMQMessage instances
and these are pushed into the consumer queues and then serialized to be sent over tcp.
I think that under some particular conditions the properties are not serialized into the marshalledProperties
field or this happens after the message has been actually sent.
My workaround is to force the marshalling of properties into the marshalledProperties field
when the message is copied using the copy method.
This is not very clean, but still acceptable. The problem is that, in order for this to work,
I need to create messages of a subclass of ActiveMqBytesMessage using an explicit constructor
call rather that session.createBytesMessage() and I need to set the connection into them.
Here is the code of my redefined class (this is the BytesMessage version, but the same is
applicable to other kinds of messages):

{noformat}
import java.io.DataOutputStream;
import java.io.IOException;

import javax.jms.Session;

import org.apache.activemq.ActiveMQSession;
import org.apache.activemq.command.ActiveMQBytesMessage;
import org.apache.activemq.command.Message;
import org.apache.activemq.util.ByteArrayOutputStream;
import org.apache.activemq.util.MarshallingSupport;

public class EarlySerializingBytesMessage extends ActiveMQBytesMessage
{
    private static final org.apache.log4j.Logger logger = org.apache.log4j.Logger.getLogger(EarlySerializingBytesMessage.class);
    
    public EarlySerializingBytesMessage(Session session)
    {
        ActiveMQSession activeMqSession = (ActiveMQSession)session;
        setConnection(activeMqSession.getConnection());
    }
    
    /*
     * We redefine <code>copy</code> to force the marshalling of properties here
and avoid a problem we've found with serialized properties 
     * arriving empty on the client side.
     * This is a workaround to make sure the properties are already serialized when ActiveMQ
actually sends the message to
     * the client.
     * This happens very rarely and it is very difficult to spot this error in a "normal"
testing session.
     * To have reasonable changes to reproduce it, we use a stress test tool that sends 5000
messages a second and at that rate
     * the error happens usually within 10 minutes, so we can say that one message every million
is typically affected.
     * The actual problem is probably due to a bug in the ActiveMQ broker. Basically, it serializes
every message just before
     * sending it and it happens that the marshalled properties are missing the resulting
message, so we get an error on the client
     * as soon as we try to read them.
     * Since we use an embedded broker, our original message is never serialized, it is passed
into the publishing queue as a Java object,
     * then it is copied into a new message of the same base type (ActiveMQBytesMessage, in
this case) and pushed into the subscribers' 
     * queues (a topic is actually implemented as a series of queues, one for each subscriber).
In order to do this, the <code>copy</code>
     * method is invoked, we redefine it to early serialize the properties and make sure that
this step is not skipped.
     */
    @Override
    public Message copy()
    {
        try
        {
            ByteArrayOutputStream baos = new ByteArrayOutputStream();
            DataOutputStream os = new DataOutputStream(baos);
            MarshallingSupport.marshalPrimitiveMap(properties, os);
            os.close();
            marshalledProperties = baos.toByteSequence();
        }
        catch(IOException exc)
        {
            logger.error("Error marhalling message properties, message was " + this, exc);
        }
        
        return super.copy();
    }
}
{noformat}


The problem happens both on Java and C# clients, with the following stacktraces:

Java:
{noformat}
javax.jms.JMSException: java.io.EOFException
        at org.apache.activemq.util.JMSExceptionSupport.create(JMSExceptionSupport.java:62)
        at org.apache.activemq.filter.PropertyExpression.evaluate(PropertyExpression.java:199)
        at org.apache.activemq.command.ActiveMQMessage.getObjectProperty(ActiveMQMessage.java:509)
        at org.apache.activemq.command.ActiveMQMessage.getStringProperty(ActiveMQMessage.java:604)
        at activemq.emptypropertiestest.Subscriber$1.onMessage(Subscriber.java:65)
        at org.apache.activemq.ActiveMQMessageConsumer.dispatch(ActiveMQMessageConsumer.java:1230)
        at org.apache.activemq.ActiveMQSessionExecutor.dispatch(ActiveMQSessionExecutor.java:134)
        at org.apache.activemq.ActiveMQSessionExecutor.iterate(ActiveMQSessionExecutor.java:205)
        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:619)
Caused by: java.io.EOFException
        at java.io.DataInputStream.readInt(DataInputStream.java:375)
        at org.apache.activemq.util.MarshallingSupport.unmarshalPrimitiveMap(MarshallingSupport.java:83)
        at org.apache.activemq.util.MarshallingSupport.unmarshalPrimitiveMap(MarshallingSupport.java:73)
        at org.apache.activemq.command.Message.unmarsallProperties(Message.java:202)
        at org.apache.activemq.command.Message.getProperty(Message.java:159)
        at org.apache.activemq.filter.PropertyExpression.evaluate(PropertyExpression.java:197)
        ... 11 more
{noformat}

C#:

{noformat}
System.IO.EndOfStreamException: Unable to read beyond the end of the stream.
   at System.IO.MemoryStream.InternalReadInt32()
   at System.IO.BinaryReader.ReadInt32()
   at Apache.NMS.Util.EndianBinaryReader.ReadInt32()
   at Apache.NMS.Util.PrimitiveMap.UnmarshalPrimitiveMap(BinaryReader dataIn)
   at Apache.NMS.Util.PrimitiveMap.UnmarshalPrimitiveMap(Byte[] data)
   at Apache.NMS.Util.PrimitiveMap.Unmarshal(Byte[] data)
   at Apache.NMS.ActiveMQ.Commands.ActiveMQMessage.get_Properties()
...
{noformat}

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