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https://issues.apache.org/jira/browse/AMQ-4122?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13583817#comment-13583817
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SuoNayi commented on AMQ-4122:
------------------------------

The cause is that LeaseDatabaseLocker always succeed updating the broker name 
(the owner of the lease lock) by later lease time in contrast to the current 
lease owner,that means new broker will always obtain the lease lock and the 
previous owner has to give up the lock and becomes slave. 

                
> Lease Database Locker failover broken
> -------------------------------------
>
>                 Key: AMQ-4122
>                 URL: https://issues.apache.org/jira/browse/AMQ-4122
>             Project: ActiveMQ
>          Issue Type: Bug
>    Affects Versions: 5.7.0
>         Environment: Java 7u9, SUSE 11, Mysql
>            Reporter: st.h
>            Assignee: Gary Tully
>             Fix For: 5.8.0
>
>         Attachments: activemq-kyle.xml, activemq.xml, activemq.xml, 
> AMQ4122.patch, mysql.log
>
>
> We are using ActiveMQ 5.7.0 together with a mysql database and could not 
> observe correct failover behavior with lease database locker.
> It seems that there is a race condition, which prevents the correct failover 
> procedure.
> We noticed that when starting up two instances, both instance are becoming 
> master.
> We did several test, including the following and could not observe intended 
> functionality:
> - shutdown all instances
> - manipulate database lock that one node has lock and set expiry time in 
> distance future
> - start up both instances. both instances are unable to acquire lock, as the 
> lock hasn't expired, which should be correct behavior.
> - update the expiry time in database, so that the lock is expired.
> - first instance notices expired lock and becomes master
> - when second instance checks for lock, it also updates the database and 
> becomes master.
> To my understanding the second instance should not be able to update the 
> lock, as it is held by the first instance and should not be able to become 
> master.

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