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From "Albert Strasheim (JIRA)" <>
Subject [jira] Reopened: (AMQCPP-90) Openwire Session doesn't run its MessageListeners from a single thread
Date Sun, 18 Mar 2007 18:04:34 GMT


Albert Strasheim reopened AMQCPP-90:

Revision 519590 seems to have broken our library's one unit test.

The test does the following:

- creates a connection
- sets an exception listener on the connection
- creates an asynchronous session
- uses the session to create one producer and one consumer associated with a topic
- sets a message listener on the consumer
- starts the connection

The test then uses the producer to send a BytesMessage to the consumer. The BytesMessage contains
a single integer. The message listener tries to read two integers from the BytesMessage.

In revision 519589 this triggered the exception listener, which signals our test method through
a latch and the test completes normally.

With revision 519590, reading the second integer causes the test to print:

Reached the end of the buffer
        FILE: ..\src\main\activemq\io\ByteArrayInputStream.cpp, LINE: 104
        FILE: ..\src\main\activemq\io\DataInputStream.cpp, LINE: 314
        FILE: ..\src\main\activemq\io\DataInputStream.cpp, LINE: 104
        FILE: ..\src\main\activemq\io\DataInputStream.cpp, LINE: 181
        FILE: ..\src\main\activemq\core\ActiveMQConsumer.cpp, LINE: 378

to the console and then the program hangs. We also see this behaviour with the latest HEAD
revision (519654).

I'm also seeing an intermittent segfault (can't reproduce it reliably yet). The stack trace
looks like this:

>	unittests.exe!activemq::core::ActiveMQConsumer::dispatch(activemq::core::DispatchData
& data={...})  Line 368 + 0x16 bytes	C++
& data={...})  Line 140	C++
 	unittests.exe!activemq::core::ActiveMQSessionExecutor::dispatchAll()  Line 185	C++
 	unittests.exe!activemq::core::ActiveMQSessionExecutor::run()  Line 152	C++
 	unittests.exe!activemq::concurrent::Thread::runCallback(void * param=0x008d3748)  Line 152
+ 0x13 bytes	C++
 	[Frames below may be incorrect and/or missing, no symbols loaded for msvcr80d.dll]	

This seems to also have caused by a recent change, as I've never seen this before today.

> Openwire Session doesn't run its MessageListeners from a single thread
> ----------------------------------------------------------------------
>                 Key: AMQCPP-90
>                 URL:
>             Project: ActiveMQ C++ Client
>          Issue Type: Bug
>          Components: Openwire
>    Affects Versions: 2.0
>            Reporter: Albert Strasheim
>         Assigned To: Nathan Mittler
>             Fix For: 2.0
>         Attachments: MultipleConsumerTest.cpp,
> According to the JMS 1.1 specification, section 4.4.14 Serial Execution of Client Code:
> For this reason, JMS does not cause concurrent execution of client code unless
> a client explicitly requests it. One way this is done is to define that a session
> serializes all asynchronous delivery of messages.
> To receive messages asynchronously, a client registers an object that
> implements the JMS MessageListener interface with a MessageConsumer. In effect,
> a Session uses a single thread to run all its MessageListeners. While the thread is
> busy executing one listener, all other messages to be asynchronously delivered
> to the session must wait.
> In the attached code I have 5 consumers created from the same session, all with the same
message listener instance that receives a message, prints something and then sleeps for a
while. When running the C++ code, one sees that 5 messages (there are 5 consumers) are delivered
at approximately the same time. Under Java, one only sees 1 message delivered per interval.
> This seems to indicate that the Openwire Session doesn't run its MessageListeners from
a single thread. This can cause problems if the user's MessageListener isn't thread safe.

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