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Date: Mon, 20 Jan 2014 10:59:13 +0800
From: Rural Hunter <ruralhunter@gmail.com>
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To: user@hbase.apache.org
Subject: Long running client got NoServerForRegionException
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Hi,

I'm using hbase 0.96.1 with hadoop2. I have a client running all the 
time. It connects to hbase when it receives data from time to time. The 
logic of this client is like this:
1. It keeps the HConnection got from 
HConnectionManager.createConnection() when the client inits.
2. It calls getTable from the HConnection kept above to access hbase 
tables from time to time.

There are serveral same clients running on several server. From one time 
point, On only one of the server, the client started to experience the 
NoServerForRegionException:
org.apache.hadoop.hbase.client.NoServerForRegionException: Unable to find region for  after 3 tries.
at org.apache.hadoop.hbase.client.HConnectionManager$HConnectionImplementation.locateRegionInMeta(HConnectionManager.java:1127)
at org.apache.hadoop.hbase.client.HConnectionManager$HConnectionImplementation.locateRegion(HConnectionManager.java:1047)
at org.apache.hadoop.hbase.client.HConnectionManager$HConnectionImplementation.locateRegion(HConnectionManager.java:1004)
at org.apache.hadoop.hbase.client.HTable.finishSetup(HTable.java:325)
at org.apache.hadoop.hbase.client.HTable.<init>(HTable.java:309)
at org.apache.hadoop.hbase.client.HConnectionManager$HConnectionImplementation.getTable(HConnectionManager.java:706)
at org.apache.hadoop.hbase.client.HConnectionManager$HConnectionImplementation.getTable(HConnectionManager.java:688)
at org.apache.hadoop.hbase.client.HConnectionManager$HConnectionImplementation.getTable(HConnectionManager.java:678)

Note the table name and rowkey after 'Unable to find region for' is 
empty. I checked the code in the client and it can never pass an empty 
table name to getTable. I also checked the master and zookeeper log but 
didn't find any error related to this. As far as I know, there could be 
some intermittent network problem between the client and the hbase 
server. What can be the cause for the error and how can I avoid/fix it?