Possible problem with autorecovery and thread safety

[Keruspe]

Hi,

In an application I'm working on, I ended up having two threads using the same channel, and one of the threads closed the channel while the other was issuing a basicGet.
I'm using the version 3.3.3 of the client.
It seems that the basicGet thread doesn't get the information that the close was intentional, and tries to recover.
I got a couple of these stacks:

Caught an exception when recovering topology Caught an exception while recovering queue edis.32: channel is already closed due to clean channel shutdown; protocol method: #method<channel.close>(reply-code=200, reply-text=OK, class-id=0, method-id=0)
com.rabbitmq.client.TopologyRecoveryException: Caught an exception while recovering queue edis.32: channel is already closed due to clean channel shutdown; protocol method: #method<channel.close>(reply-code=200, reply-text=OK, class-id=0, method-id=0)
at com.rabbitmq.client.impl.recovery.AutorecoveringConnection.recoverQueues(AutorecoveringConnection.java:461)
at com.rabbitmq.client.impl.recovery.AutorecoveringConnection.recoverEntities(AutorecoveringConnection.java:422)
at com.rabbitmq.client.impl.recovery.AutorecoveringConnection.beginAutomaticRecovery(AutorecoveringConnection.java:365)
at com.rabbitmq.client.impl.recovery.AutorecoveringConnection.access$000(AutorecoveringConnection.java:48)
at com.rabbitmq.client.impl.recovery.AutorecoveringConnection$1.shutdownCompleted(AutorecoveringConnection.java:345)
at com.rabbitmq.client.impl.ShutdownNotifierComponent.notifyListeners(ShutdownNotifierComponent.java:75)
at com.rabbitmq.client.impl.AMQConnection$MainLoop.run(AMQConnection.java:572)
at java.lang.Thread.run(Thread.java:744)
Caused by: com.rabbitmq.client.AlreadyClosedException: channel is already closed due to clean channel shutdown; protocol method: #method<channel.close>(reply-code=200, reply-text=OK, class-id=0, method-id=0)
at com.rabbitmq.client.impl.AMQChannel.ensureIsOpen(AMQChannel.java:190)
at com.rabbitmq.client.impl.AMQChannel.rpc(AMQChannel.java:223)
at com.rabbitmq.client.impl.AMQChannel.privateRpc(AMQChannel.java:209)
at com.rabbitmq.client.impl.AMQChannel.exnWrappingRpc(AMQChannel.java:118)
at com.rabbitmq.client.impl.ChannelN.queueDeclare(ChannelN.java:779)
at com.rabbitmq.client.impl.recovery.AutorecoveringChannel.queueDeclare(AutorecoveringChannel.java:231)
at com.rabbitmq.client.impl.recovery.RecordedQueue.recover(RecordedQueue.java:36)
at com.rabbitmq.client.impl.recovery.AutorecoveringConnection.recoverQueues(AutorecoveringConnection.java:448)
... 7 more

[michaelklishin]

Channels should not be shared between threads (not because recovery doesn't try to synchronize with other operations but for many reasons). Channel#basicGet does not kick off connection recovery,
something has closed the connection underneath the thread that uses basic.get.

It's not realistic for a client library to handle such scenarios, they are application-specific.