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https://issues.apache.org/jira/browse/AMQ-7132?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16743471#comment-16743471
 ] 

Jamie goodyear commented on AMQ-7132:
-------------------------------------

Those tests passed for me as well.

-------------------------------------------------------
 T E S T S
-------------------------------------------------------
Running org.apache.activemq.broker.RecoveryStatsBrokerTest
Tests run: 3, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 21.901 sec - in 
org.apache.activemq.broker.RecoveryStatsBrokerTest

Results :

Tests run: 3, Failures: 0, Errors: 0, Skipped: 0


icbts-2:activemq-unit-tests icbts$ mvn -version
Apache Maven 3.5.3 (3383c37e1f9e9b3bc3df5050c29c8aff9f295297; 
2018-02-24T16:19:05-03:30)
Maven home: /x1/maven/apache-maven-3.5.3
Java version: 1.8.0_171, vendor: Oracle Corporation
Java home: /Library/Java/JavaVirtualMachines/jdk1.8.0_171.jdk/Contents/Home/jre
Default locale: en_CA, platform encoding: UTF-8
OS name: "mac os x", version: "10.14.1", arch: "x86_64", family: "mac"

> ActiveMQ reads lots of index pages upon startup (after a graceful or 
> ungraceful shutdown)
> -----------------------------------------------------------------------------------------
>
>                 Key: AMQ-7132
>                 URL: https://issues.apache.org/jira/browse/AMQ-7132
>             Project: ActiveMQ
>          Issue Type: Improvement
>          Components: KahaDB
>    Affects Versions: 5.15.8
>            Reporter: Alan Protasio
>            Assignee: Christopher L. Shannon
>            Priority: Major
>             Fix For: 5.16.0
>
>         Attachments: output.tgz
>
>
> Hi.
> We noticed that ActiveMQ reads lots of pages in the index file when is 
> starting up to recover the destinations statistics:
> [https://github.com/apache/activemq/blob/master/activemq-kahadb-store/src/main/java/org/apache/activemq/store/kahadb/KahaDBStore.java#L819]
> Nowadays, in order to do that, activemq traverse the 
> storedDestination.locationIndex to get the messageCount and totalMessageSize 
> of each destination. For destinations with lots of messages this process can 
> take a while making the startup process take long time.
> In a case of a master-slave broker, this prevent the broker to fast failover 
> and does not meet what is stated on 
> [http://activemq.apache.org/shared-file-system-master-slave.html.]
> {quote}If you have a SAN or shared file system it can be used to provide 
> _high availability_ such that if a broker is killed, another broker can take 
> over immediately. 
> {quote}
> One solution for this is keep track of the destination statistics summary in 
> the index file and doing so, we dont need to read all the locationIndex on 
> the start up.
> The code change proposed is backward compatible but need a bump on the kahadb 
> version. If this information is not in the index, the broker will fall back 
> to the current implementation, which means that the first time people upgrade 
> to the new version, it will still have to read the locationIndex, but 
> subsequent restarts will be fast.
> This change should have a negligible performance impact during normal 
> activemq operation, as this change introduce a few more bytes of data to the 
> index and this information will be on checkpoints. Also, this new information 
> is synchronized with the locationIndex as they are update at the same 
> transaction.



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