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https://issues.apache.org/jira/browse/AMQ-5077?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13985618#comment-13985618
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Gary Tully commented on AMQ-5077:
---------------------------------
For 2, even with async sends, we were serialising store writes. I have changed
that in http://git-wip-us.apache.org/repos/asf/activemq/commit/ad1f751a
A client can now fill the destination cache (essentially consume all the
destination memory resources) without waiting on a disk write. The transport
reader thread does a cursor/cache update (which is serialised) and goes back to
read which gives a marked improvement.
Once the cache is exhausted, the write revert to sync so the read thread
blocks. This makes sense because there are no broker resources to store pending
writes.
For the composite case, the virtual topic send waits for each of the fanout
sends to complete. Otherwise, there would be no way to limit the broker
resources for pending composite sends.
So the key point to dealing with bursts (and getting them to the broker asap)
is to ensure that the destination memory limits can accommodate it.
> Improve performance of ConcurrentStoreAndDispatch
> -------------------------------------------------
>
> Key: AMQ-5077
> URL: https://issues.apache.org/jira/browse/AMQ-5077
> Project: ActiveMQ
> Issue Type: Wish
> Components: Message Store
> Affects Versions: 5.9.0
> Environment: 5.9.0.redhat-610343
> Reporter: Jason Shepherd
> Assignee: Gary Tully
> Attachments: Test combinations.xlsx, compDesPerf.tar.gz,
> topicRouting.zip
>
>
> We have publishers publishing to a topic which has 5 topic -> queue routings,
> and gets a max message rate attainable of ~833 messages/sec, with each
> message around 5k in size.
> To test this i set up a JMS config with topic queues:
> Topic
> TopicRouted.1
> ...
> TopicRouted.11
> Each topic has an increasing number of routings to queues, and a client is
> set up to subscribe to all the queues.
> Rough message rates:
> routings messages/sec
> 0 2500
> 1 1428
> 2 2000
> 3 1428
> 4 1111
> 5 833
> This occurs whether the broker config has producerFlowControl="false" set to
> true or false , and KahaDB disk synching is turned off. We also tried
> experimenting with concurrentStoreAndDispatch, but that didn't seem to help.
> LevelDB didn't give any notable performance improvement either.
> We also have asyncSend enabled on the producer, and have a requirement to use
> persistent messages. We have also experimented with sending messages in a
> transaction, but that hasn't really helped.
> It seems like producer throughput rate across all queue destinations, all
> connections and all publisher machines is limited by something on the broker,
> through a mechanism which is not producer flow control. I think the prime
> suspect is still contention on the index.
> We did some test with Yourkit profiler.
> Profiler was attached to broker at startup, allowed to run and then a topic
> publisher was started, routing to 5 queues.
> Profiler statistics were reset, the publisher allowed to run for 60 seconds,
> and then profiling snapshot was taken. During that time, ~9600 messages were
> logged as being sent for a rate of ~160/sec.
> This ties in roughly with the invocation counts recorded in the snapshot (i
> think) - ~43k calls.
> From what i can work out, in the snapshot (filtering everything but
> org.apache.activemq.store.kahadb),
> For the 60 second sample period,
> 24.8 seconds elapsed in
> org.apache.activemq.store.kahadb.KahaDbTransactionStore$1.removeAsyncMessage(ConnectionContext,
> MessageAck).
> 18.3 seconds elapsed in
> org.apache.activemq.store.kahadb.KahaDbTransactionStore$1.asyncAddQueueMessage(ConnectionContext,
> Message, boolean).
> From these, a further large portion of the time is spent inside
> MessageDatabase:
> org.apache.activemq.store.kahadb.MessageDatabase.process(KahaRemoveMessageCommand,
> Location) - 10 secs elapsed
> org.apache.activemq.store.kahadb.MessageDatabase.process(KahaAddMessageCommand,
> Location) - 8.5 secs elapsed.
> As both of these lock on indexLock.writeLock(), and both take place on the
> NIO transport threads, i think this accounts for at least some of the message
> throughput limits. As messages are added and removed from the index one by
> one, regardless of sync type settings, this adds a fair amount of overhead.
> While we're not synchronising on writes to disk, we are performing work on
> the NIO worker thread which can block on locks, and could account for the
> behaviour we've seen client side.
> To Reproduce:
> 1. Install a broker and use the attached configuration.
> 2. Use the 5.8.0 example ant script to consume from the queues,
> TopicQueueRouted.1 - 5. eg:
> ant consumer -Durl=tcp://localhost:61616 -Dsubject=TopicQueueRouted.1
> -Duser=admin -Dpassword=admin -Dmax=-1
> 3. Use the modified version of 5.8.0 example ant script (attached) to send
> messages to topics, TopicRouted.1 - 5, eg:
> ant producer
> -Durl='tcp://localhost:61616?jms.useAsyncSend=true&wireFormat.tightEncodingEnabled=false&keepAlive=true&wireFormat.maxInactivityDuration=60000&socketBufferSize=32768'
> -Dsubject=TopicRouted.1 -Duser=admin -Dpassword=admin -Dmax=1 -Dtopic=true
> -DsleepTime=0 -Dmax=10000 -DmessageSize=5000
> This modified version of the script prints the number of messages per second
> and prints it to the console.
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