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https://issues.apache.org/activemq/browse/AMQNET-289?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Morgan Martinet updated AMQNET-289:
-----------------------------------
Attachment: SessionExecutor.cs
deadlock fix.
> Deadlock while sending a message after failover within a consumer
> -----------------------------------------------------------------
>
> Key: AMQNET-289
> URL: https://issues.apache.org/activemq/browse/AMQNET-289
> Project: ActiveMQ .Net
> Issue Type: Bug
> Components: ActiveMQ
> Affects Versions: 1.4.1
> Environment: Windows 7 64 bits
> Reporter: Morgan Martinet
> Assignee: Jim Gomes
> Priority: Critical
> Attachments: SessionExecutor.cs
>
>
> Scenario:
> - I have one producer that sends a request (with a temporary queue specified
> in the Reply-to attribute) to a consumer, in a separate process.
> - both, the producer and the consumer, use the following connection string:
> failover:(tcp://localhost:61616)?timeout=3000
> - the consumer, when processing the request, waits 10 seconds then sends a
> response back, using the Reply-To attribute.
> - immediately after the message has been sent, while the consumer is waiting
> for 10 secs, I restart the ActiveMQ broker.
> - once the the consumer wakes up and tries to send its reply, it will
> deadlock because of the failover.
> We have managed to identify the resources that deadlock:
> Thread1 - lock(reconnectMutex)
> (c:\Temp\Apache\NMS.ActiveMQ\1.4.1\src\main\csharp\Transport\Failover\FailoverTransport.cs:
> line 366)
> Thread1 - wait on lock(this.consumers.SyncRoot)
> (c:\Temp\Apache\NMS.ActiveMQ\1.4.1\src\main\csharp\Session.cs: line 830)
> Thread2 - lock(this.consumers.SyncRoot)
> (c:\Temp\Apache\NMS.ActiveMQ\1.4.1\src\main\csharp\SessionExecutor.cs: line
> 147)
> Thread2 - wait on lock(reconnectMutex)
> (c:\Temp\Apache\NMS.ActiveMQ\1.4.1\src\main\csharp\Transport\Failover\FailoverTransport.cs:
> line 531)
> Patch:
> I managed to find a simple fix for this, by moving the consumer dispatch out
> of the this.consumers.SyncRoot lock in SessionExecutor.cs:
> {{
> public void Dispatch(MessageDispatch dispatch)
> {
> try
> {
> MessageConsumer consumer = null;
> lock(this.consumers.SyncRoot)
> {
> if(this.consumers.Contains(dispatch.ConsumerId))
> {
> consumer = this.consumers[dispatch.ConsumerId] as
> MessageConsumer;
> }
> // Note that consumer.Dispatch(...) was moved below, outside of the lock.
> }
> // If the consumer is not available, just ignore the message.
> // Otherwise, dispatch the message to the consumer.
> if(consumer != null) {
> consumer.Dispatch(dispatch);
> }
> }
> catch(Exception ex)
> {
> Tracer.DebugFormat("Caught Exception While Dispatching: {0}",
> ex.Message );
> }
> }
> }}
> Note that I ran the unit tests before my patch and I got 3 failures. Then I
> got the same failures with my patch. So, I hope it didn't break anything but
> I'll let you find the best solution...
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