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From "Gary Tully (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (AMQ-4122) Lease Database Locker failover broken
Date Mon, 25 Feb 2013 12:08:13 GMT

    [ https://issues.apache.org/jira/browse/AMQ-4122?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13585816#comment-13585816
] 

Gary Tully commented on AMQ-4122:
---------------------------------

@SouNayi  - thanks for the feedback. on {quote}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.{quote}

Can you make a variant of https://fisheye6.atlassian.com/viewrep/activemq/trunk/activemq-core/src/test/java/org/apache/activemq/store/jdbc/LeaseDatabaseLockerTest.java
that shows the problem? I don't see a problem against derby in the unit test. Note: in the
unit test there is no periodic call to keepalive.
The intent of the update to acquire a lock checks the TIME value against current time and
sets it to obtain the lease. It should (and does) fail if the lease is still valid. ie: the
time is set to a value in the future.https://issues.apache.org/jira/browse/AMQ-4122?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#
                
> 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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