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From "Gary Tully (JIRA)" <>
Subject [jira] [Commented] (AMQ-4935) Deadlock caused by Re-entrant lock with no locking thread
Date Fri, 13 Dec 2013 13:17:07 GMT


Gary Tully commented on AMQ-4935:

you can only avoid serialization if both ends are inVM; Seems like you are producing to a
topic over vm transport but you have more than one subscription over tcp and they are contending
for access when they want to serialize.

> Deadlock caused by Re-entrant lock with no locking thread
> ---------------------------------------------------------
>                 Key: AMQ-4935
>                 URL:
>             Project: ActiveMQ
>          Issue Type: Bug
>          Components: Broker
>    Affects Versions: 5.9.0
>         Environment: Oracle JRE 1.7.0 update 45
>            Reporter: Michael Yara
> We have a distributed application that uses ActiveMQ for communication between nodes.
We are currently using ActiveMQ 5.9.0 running with Oracle JRE 1.7.0 update 45. 
> We are seeing some strange deadlock behavior in the ActiveMQ ThreadPoolExecutor when
trying to serialize instances of ConcurrentHashMap. The thread dump can be seen at the following
> We can see that there are two threads that are blocked waiting for a lock on some of
the segments in a ConcurrentHashMap yet the thread dump does not indicate any threads that
currently hold a lock on those objects. This lock does not occur all the time and can take
around 5-10 messages before the deadlock occurs. I have been able to recreate this issue on
two different physical machines.
> Our test environment that generated this thread dump is as follows. Node A is the instance
that thread dump was taken from. For testing both nodes are on the same physical machine.
> Node A:
> * In its own JVM instance.
> * Runs an embedded ActiveMQ broker.
> * Performs communication via vm transport and sends ObjectMessages via a TopicConnection.
> * Has copyMessageOnSend=false
> * Has ObjectMessageSerializationDefered=true
> Node B:
> * In its own JVM instance.
> * Connects to Node A's broker via tcp transport.
> * Sends BytesMessages serialized with Kryo and sent via a TopicConnection.
> * Has copyMessageOnSend=false
> * Has ObjectMessageSerializationDefered=false
> Both nodes are set up to detect the type of incoming messages and deserialize them appropriately
with kryo if it receives a BytesMessage or default serialization if it receives an ObjectMessage
(handled by ActiveMQ).
> The only thing I have found resembling this issue is the following link. I am no sure
if it is related to this exact problem or not.

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