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https://issues.apache.org/jira/browse/AMQ-4122?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13583010#comment-13583010
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SuoNayi commented on AMQ-4122:
------------------------------

I also see the same unexpected behavior experienced by st.h.
New broker starts up will obtain the lease lock successfully every time and no 
slaves can keep standing.
The patch I attached may reveal the cause.
                
> 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, 
> LeaseDatabaseLocker.java.patch
>
>
> 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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