Its there for message exclusive consumers - will look at changing ;)
On Feb 8, 2008, at 4:09 PM, David Sitsky wrote:
In my application, I have a large number of threads in the broker,
which are calling dispatchPending() on their subscriptions, but are
unable to make fast progress, as can be seen in the following stack
trace:
"ActiveMQ Transport: tcp:///192.168.222.75:56495" daemon prio=4
tid=0x4be82000 n
id=0x1028 waiting for monitor entry [0x54fdf000..0x54fdfb00]
java.lang.Thread.State: BLOCKED (on object monitor)
at org.apache.activemq.broker.region.Queue.lock(Queue.java:166)
- locked <0x0a60bf58> (a java.lang.Object)
at
org
.apache
.activemq
.broker
.region.IndirectMessageReference.lock(IndirectMessageReference.java:
143)
at
org
.apache
.activemq
.broker.region.QueueSubscription.canDispatch(QueueSubscription.java:
119)
at
org
.apache
.activemq
.broker
.region
.PrefetchSubscription.dispatchPending(PrefetchSubscription.java:466)
- locked <0x0b55bd78> (a java.lang.Object)
at
org
.apache
.activemq
.broker
.region.PrefetchSubscription.acknowledge(PrefetchSubscription.java:
347)
at
org
.apache
.activemq
.broker.region.AbstractRegion.acknowledge(AbstractRegion.java:342)
at
org
.apache
.activemq.broker.region.RegionBroker.acknowledge(RegionBroker.java:
461)
at
org
.apache
.activemq
.broker.TransactionBroker.acknowledge(TransactionBroker.java:194)
at
org
.apache.activemq.broker.BrokerFilter.acknowledge(BrokerFilter.java:73)
at
org
.apache.activemq.broker.BrokerFilter.acknowledge(BrokerFilter.java:73)
at
org
.apache
.activemq
.broker.MutableBrokerFilter.acknowledge(MutableBrokerFilter.java:87)
at
org
.apache
.activemq
.broker
.TransportConnection.processMessageAck(TransportConnection.java:440)
at
org.apache.activemq.command.MessageAck.visit(MessageAck.java:196)
....
I am trying to understand why IndirectMessageReference.lock() would
require synchronisation on the entire Queue object it is associated
with?
This is why the performance in my application is grinding... each
time a prefetch/queue subscription is testing to see if they can
dispatch a message, we are effectively serialising on the Queue
object.
Any ideas on how we can fix this? I have some ideas, but thought
the experts are better qualified. :)
This became evident when I had 20 consumers hammering away. With 2,
you'd never see this.
Cheers,
David
