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Posted to issues@hbase.apache.org by "Himanshu Vashishtha (JIRA)" <ji...@apache.org> on 2012/12/27 01:08:12 UTC

[jira] [Created] (HBASE-7440) ReplicationZookeeper#addPeer is racy

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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