Hbase managed zookeeper suddenly trying to connect to localhost instead of zookeeper quorum

Question

I was running some tests with table mappers and reducers on large scale problems. After a certain point my reducers started failing when the job was 80% done. From what I can tell when looking at the syslogs the problem is that one of my zookeepers is attempting to connect to the localhost as opposed to the other zookeepers in the quorum

Oddly it seems to do just fine connecting to the other nodes when mapping is going on, its reducing that it has a problem with. Here are selected portions of the syslog which might be relevant to figuring out whats going on

2014-06-27 09:44:01,599 INFO [main] org.apache.zookeeper.ZooKeeper: Initiating client connection, connectString=hdev02:5181,hdev01:5181,hdev03:5181 sessionTimeout=10000 watcher=hconnection-0x4aee260b, quorum=hdev02:5181,hdev01:5181,hdev03:5181, baseZNode=/hbase
2014-06-27 09:44:01,612 INFO [main] org.apache.hadoop.hbase.zookeeper.RecoverableZooKeeper: Process identifier=hconnection-0x4aee260b connecting to ZooKeeper ensemble=hdev02:5181,hdev01:5181,hdev03:5181
2014-06-27 09:44:01,614 INFO [main-SendThread(hdev02:5181)] org.apache.zookeeper.ClientCnxn: Opening socket connection to server hdev02/172.17.43.36:5181. Will not attempt to authenticate using SASL (Unable to locate a login configuration)
2014-06-27 09:44:01,615 INFO [main-SendThread(hdev02:5181)] org.apache.zookeeper.ClientCnxn: Socket connection established to hdev02/172.17.43.36:5181, initiating session
2014-06-27 09:44:01,617 INFO [main-SendThread(hdev02:5181)] org.apache.zookeeper.ClientCnxn: Unable to read additional data from server sessionid 0x0, likely server has closed socket, closing socket connection and attempting reconnect
2014-06-27 09:44:01,723 WARN [main] org.apache.hadoop.hbase.zookeeper.RecoverableZooKeeper: Possibly transient ZooKeeper, quorum=hdev02:5181,hdev01:5181,hdev03:5181, exception=org.apache.zookeeper.KeeperException$ConnectionLossException: KeeperErrorCode = ConnectionLoss for /hbase/hbaseid
2014-06-27 09:44:01,723 INFO [main] org.apache.hadoop.hbase.util.RetryCounter: Sleeping 
***
org.apache.hadoop.mapreduce.task.reduce.MergeManagerImpl: finalMerge called with 1 in-memory map-outputs and 1 on-disk map-outputs
2014-06-27 09:55:12,012 INFO [main] org.apache.hadoop.mapred.Merger: Merging 1 sorted segments
2014-06-27 09:55:12,013 INFO [main] org.apache.hadoop.mapred.Merger: Down to the last merge-pass, with 1 segments left of total size: 33206049 bytes
2014-06-27 09:55:12,208 INFO [main] org.apache.hadoop.mapreduce.task.reduce.MergeManagerImpl: Merged 1 segments, 33206079 bytes to disk to satisfy reduce memory limit
2014-06-27 09:55:12,209 INFO [main] org.apache.hadoop.mapreduce.task.reduce.MergeManagerImpl: Merging 2 files, 265119413 bytes from disk
2014-06-27 09:55:12,209 INFO [main] org.apache.hadoop.mapreduce.task.reduce.MergeManagerImpl: Merging 0 segments, 0 bytes from memory into reduce
2014-06-27 09:55:12,210 INFO [main] org.apache.hadoop.mapred.Merger: Merging 2 sorted segments
2014-06-27 09:55:12,212 INFO [main] org.apache.hadoop.mapred.Merger: Down to the last merge-pass, with 2 segments left of total size: 265119345 bytes
2014-06-27 09:55:12,279 INFO [main] org.apache.zookeeper.ZooKeeper: Initiating client connection, connectString=localhost:2181 sessionTimeout=90000 watcher=hconnection-0x65afdbbb, quorum=localhost:2181, baseZNode=/hbase
2014-06-27 09:55:12,281 INFO [main] org.apache.hadoop.hbase.zookeeper.RecoverableZooKeeper: Process identifier=hconnection-0x65afdbbb connecting to ZooKeeper ensemble=localhost:2181
2014-06-27 09:55:12,282 INFO [main-SendThread(localhost.localdomain:2181)] org.apache.zookeeper.ClientCnxn: Opening socket connection to server localhost.localdomain/127.0.0.1:2181. Will not attempt to authenticate using SASL (Unable to locate a login configuration)
2014-06-27 09:55:12,283 WARN [main-SendThread(localhost.localdomain:2181)] org.apache.zookeeper.ClientCnxn: Session 0x0 for server null, unexpected error, closing socket connection and attempting reconnect
java.net.ConnectException: Connection refused
    at sun.nio.ch.SocketChannelImpl.checkConnect(Native Method)
    at sun.nio.ch.SocketChannelImpl.finishConnect(SocketChannelImpl.java:599)
    at org.apache.zookeeper.ClientCnxnSocketNIO.doTransport(ClientCnxnSocketNIO.java:350)
    at org.apache.zookeeper.ClientCnxn$SendThread.run(ClientCnxn.java:1068)
2014-06-27 09:55:12,384 WARN [main] org.apache.hadoop.hbase.zookeeper.RecoverableZooKeeper: Possibly transient ZooKeeper, quorum=localhost:2181, exception=org.apache.zookeeper.KeeperException$ConnectionLossException: KeeperErrorCode = ConnectionLoss for /hbase/hbaseid
2014-06-27 09:55:12,384 INFO [main] org.apache.hadoop.hbase.util.RetryCounter: Sleeping 1000ms before retry #0...
2014-06-27 09:55:13,385 INFO [main-SendThread(localhost.localdomain:2181)] org.apache.zookeeper.ClientCnxn: Opening socket connection to server localhost.localdomain/127.0.0.1:2181. Will not attempt to authenticate using SASL (Unable to locate a login configuration)
2014-06-27 09:55:13,385 WARN [main-SendThread(localhost.localdomain:2181)] org.apache.zookeeper.ClientCnxn: Session 0x0 for server null, unexpected error, closing 
***
org.apache.hadoop.hbase.zookeeper.RecoverableZooKeeper: Possibly transient ZooKeeper, quorum=localhost:2181, exception=org.apache.zookeeper.KeeperException$ConnectionLossException: KeeperErrorCode = ConnectionLoss for /hbase/hbaseid
2014-06-27 09:55:13,486 ERROR [main] org.apache.hadoop.hbase.zookeeper.RecoverableZooKeeper: ZooKeeper exists failed after 1 attempts
2014-06-27 09:55:13,486 WARN [main] org.apache.hadoop.hbase.zookeeper.ZKUtil: hconnection-0x65afdbbb, quorum=localhost:2181, baseZNode=/hbase Unable to set watcher on znode (/hbase/hbaseid)
org.apache.zookeeper.KeeperException$ConnectionLossException: KeeperErrorCode = ConnectionLoss for /hbase/hbaseid

I'm pretty sure its configured correctly, here is the relevant portion of my hbase-site.xml.

<property>
  <name>hbase.zookeeper.property.clientPort</name>
  <value>5181</value>
  <description>Property from ZooKeeper's config zoo.cfg.
    The port at which the clients will connect.
    </description>
</property>
<property>
  <name>zookeeper.session.timeout</name>
  <value>10000</value>
  <description></description>
</property>
<property>
  <name>hbase.client.retries.number</name>
  <value>10</value>
  <description></description>
</property>
<property>
  <name>hbase.zookeeper.quorum</name>
  <value>hdev01,hdev02,hdev03</value>
  <description></description>
</property>

So far as I can tell hdev03 is the only server that has any problem with this. Netstating all relevant ports doesn't show me anything strange.

Answer 1

I've had same problem when running HBase through Spark on Yarn. Everything was fine until suddenly it started to trying to connect to localhost instead of quorum. Setting port and quorum programmatically before HBase call fixed the issue

conf.set("hbase.zookeeper.quorum","my.server")
conf.set("hbase.zookeeper.property.clientPort","5181")

I'm using MapR, and it has "unusual" (5181) zookeeper port

Answer 2

Hard to say what is happening with the information, given. I have found the Hadoop Stack (HBase especially) to be quite hostile to even the slightest bit of misconfiguration in DNS or the hosts file.

As the quorum in your hbase-site.xml looks good, I'd start checking with network/hostname resolution related configurations:

• Has the nodename slipped into the localhost entry in /etc/hosts on hdev03?
• Is there an entry for the host itself in hdev03s /etc/hosts (there should)?
• Has Reverse DNS been correctly configured in case you are using DNS for name resolution instead of the hosts file?

These are just a few pointers in the direction I'd look with this kind of issue. Hope it helps!