Daniel P Truitt created ACCUMULO-1277:
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Summary: 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: 1.4.3, 1.5.0
Reporter: Daniel P Truitt
Assignee: Eric Newton
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.
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