Himanshu Vashishtha created HBASE-7440:
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Summary: ReplicationZookeeper#addPeer is racy
Key: HBASE-7440
URL: https://issues.apache.org/jira/browse/HBASE-7440
Project: HBase
Issue Type: Bug
Components: Replication
Affects Versions: 0.94.3
Reporter: Himanshu Vashishtha
Assignee: Himanshu Vashishtha
Fix For: 0.96.0, 0.94.4
While adding a peer, ReplicationZK does the znodes creation in three
transactions. Create :
a) peers znode
b) peerId specific znode, and
c) peerState znode
There is a PeerWatcher which invokes getPeer() (after steps b) and c)). If it
happens that while adding a peer, the control flows to getPeer() and step c)
has not been processed, it may results in a state where the peer will not be
added. This happens while running TestMasterReplication#testCyclicReplication().
{code}
2012-12-26 07:36:35,187 INFO
[RegionServer:0;p0120.XXXXX,38423,1356536179470-EventThread]
zookeeper.RecoverableZooKeeper(447): Node /2/replication/peers/1/peer-state
already exists and this is not a retry
2012-12-26 07:36:35,188 ERROR
[RegionServer:0;p0120.XXXXX,38423,1356536179470-EventThread]
regionserver.ReplicationSourceManager$PeersWatcher(527): Error while adding a
new peer
org.apache.zookeeper.KeeperException$NodeExistsException: KeeperErrorCode =
NodeExists for /2/replication/peers/1/peer-state
at org.apache.zookeeper.KeeperException.create(KeeperException.java:119)
at org.apache.zookeeper.KeeperException.create(KeeperException.java:51)
at org.apache.zookeeper.ZooKeeper.create(ZooKeeper.java:783)
at
org.apache.hadoop.hbase.zookeeper.RecoverableZooKeeper.createNonSequential(RecoverableZooKeeper.java:428)
at
org.apache.hadoop.hbase.zookeeper.RecoverableZooKeeper.create(RecoverableZooKeeper.java:410)
at
org.apache.hadoop.hbase.zookeeper.ZKUtil.createAndWatch(ZKUtil.java:1044)
at
org.apache.hadoop.hbase.replication.ReplicationPeer.startStateTracker(ReplicationPeer.java:82)
at
org.apache.hadoop.hbase.replication.ReplicationZookeeper.getPeer(ReplicationZookeeper.java:344)
at
org.apache.hadoop.hbase.replication.ReplicationZookeeper.connectToPeer(ReplicationZookeeper.java:307)
at
org.apache.hadoop.hbase.replication.regionserver.ReplicationSourceManager$PeersWatcher.nodeChildrenChanged(ReplicationSourceManager.java:519)
at
org.apache.hadoop.hbase.zookeeper.ZooKeeperWatcher.process(ZooKeeperWatcher.java:315)
at
org.apache.zookeeper.ClientCnxn$EventThread.processEvent(ClientCnxn.java:519)
at org.apache.zookeeper.ClientCnxn$EventThread.run(ClientCnxn.java:495)
2012-12-26 07:36:35,188 DEBUG
[RegionServer:0;p0120.XXXXX,55742,1356536171947-EventThread]
zookeeper.ZKUtil(1545): regionserver:55742-0x13bd7db39580004 Retrieved 36
byte(s) of data from znode /1/hbaseid; data=9ce66123-d3e8-4ae9-a249-afe03...
{code}
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