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https://issues.apache.org/jira/browse/AMQ-3720?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13208861#comment-13208861
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Timothy Bish commented on AMQ-3720:
-----------------------------------
I don't think that this is needed, the session commit or message acknowledge
won't cause any deadlocks if called while a receive is blocked waiting as far
as I can tell, the locking on the session is unnecessary.
> ActiveMqMessageConsumer should have a blocking message wait that does not
> require Session synchronization
> ---------------------------------------------------------------------------------------------------------
>
> Key: AMQ-3720
> URL: https://issues.apache.org/jira/browse/AMQ-3720
> Project: ActiveMQ
> Issue Type: Improvement
> Components: JMS client
> Reporter: Martin Serrano
> Fix For: 5.6.0
>
>
> According to the documentation I've read and response to message
> [posts|http://activemq.2283324.n4.nabble.com/are-session-commit-and-consumer-receive-allowed-simultaneously-in-separate-threads-tt4387875.html],
> I've concluded that a call to consumer.receive(long) must guard against
> another thread using the session the consumer was created with.
> This makes it difficult to write performant code because a busy-wait idiom
> must be used in order to not hold a lock on session access while waiting for
> new messages. I've implemented a new method that will block until messages
> are available but does not require a session lock (it does not return any
> messages):
> {code:java}
> /**
> * Waits until messages are available. Unless the caller is interrupted,
> there will be a message available when this
> * method returns.
> */
> public void waitUntilMessagesAvailable() {
> while (unconsumedMessages.isEmpty()) {
> synchronized (unconsumedMessages.getMutex()) {
> try {
> unconsumedMessages.getMutex().wait(2000); // the dispatch channel
> notifies when a message arrives
> } catch (InterruptedException e) {
> break;
> }
> }
> }
> }
> {code}
> I'll be happy to submit as a patch with associated unit test if there is
> consensus that this is needed and useful.
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