Deadlocks can occur with even with sync sends since they share a connection.

• Key: AMQ-1183
• Type: Bug
• Status: Resolved
• Resolution: Fixed
• Priority: Major
• Assignee: Hiram Chirino
• Reporter: Hiram Chirino
• Component/s: Broker
• Fix Version/s: 4.1.1

Description

If a producer sends to a queue and blocks, any other producer sharing the same connection even if he would be sending to an empty queue would also block. This in effect can cause a deadlock if the right message processing flow is set up.

Comments

[Hiram Chirino]

Workaround fix has been implemented in http://svn.apache.org/viewvc?view=rev&revision=511078 in the 4.1 branch.

Basically, if producer uses sync sends, he now can not block another producer on the shared connection. To force all sends to be done sync, a new 'useSyncSend' option has been add to the ActiveMQConnectionFactory.

We should consider implementing a more robust soultion that will work even with async sends in 5.0. This could be done by using producer flow control with acks similar to how we flow control consumers.

[Hiram Chirino]

The following revision was also part of the fix: http://svn.apache.org/viewvc?view=rev&rev=511093

[Nathan Mittler]

Is this an AMQCPP Issue? The comments seem to imply a patch to the broker.

[Hiram Chirino]

fixed.