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https://issues.apache.org/jira/browse/ACCUMULO-1277?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13632883#comment-13632883
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Daniel P Truitt commented on ACCUMULO-1277:
-------------------------------------------
It seems like a lot of the locking complexity in Accumulo might be alleviated
by upgrading to the 3.4.x versions of zookeeper, which supports multi-operation
transactions.
> Race condition between master and tserver when acquiring tserver lock
> ---------------------------------------------------------------------
>
> Key: ACCUMULO-1277
> URL: https://issues.apache.org/jira/browse/ACCUMULO-1277
> Project: Accumulo
> Issue Type: Bug
> Components: master, tserver
> Affects Versions: 1.5.0, 1.4.3
> Reporter: Daniel P Truitt
> Assignee: Keith Turner
>
> When restarting a stopped tserver, the following happens:
> The tserver (in TabletServer.announceExistence()) creates an entry in
> zookeeper at /accumulo/instance-id/tserver/host:port.
> This in turn triggers master to execute the call chain:
> LiveTServerSet.process(WatchedEvent)
> LiveTServerSet.scanServers()
> LiveTServerSet.checkServer(Set<TServerInstance>, Set<TServerInstance>,
> String, String)
> The checkServer() method checks to see if the ZooLock data has been created
> yet (if tserver loses the race, it has not yet been created) causing master
> to then delete the tserver node.
> When the tserver attempts to create the ZooLock, the parent path no longer
> exists and creating the lock fails. Eventually the tserver will time out
> waiting to create the lock, and fail to start.
> This problem is easier to reproduce in a smallish cluster using a single
> zookeeper node, where there is more latency between the tserver and zookeeper
> than there is between the master and zookeeper.
> This behavior was introduced in the fix for ACCUMULO-1049.
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