Dear all,
Some exceptions are raised when I concurrently read data from HBase.
The version of HBase I used is 0.92.0.
I cannot fix the problem. Could you please help me?
Thanks so much!
Best wishes,
Bing
Feb 6, 2013 12:21:31 AM
org.apache.hadoop.hbase.ipc.HBaseClient$Connection run
WARNING: Unexpected exception receiving call responses
java.lang.NullPointerException
at
org.apache.hadoop.hbase.io.HbaseObjectWritable.readObject(HbaseObjectWritable.java:521)
at
org.apache.hadoop.hbase.io.HbaseObjectWritable.readFields(HbaseObjectWritable.java:297)
at
org.apache.hadoop.hbase.ipc.HBaseClient$Connection.receiveResponse(HBaseClient.java:593)
at
org.apache.hadoop.hbase.ipc.HBaseClient$Connection.run(HBaseClient.java:505)
Feb 6, 2013 12:21:31 AM
org.apache.hadoop.hbase.client.ScannerCallable close
WARNING: Ignore, probably already closed
java.io.IOException: Call to greatfreeweb/127.0.1.1:60020
failed on local exception: java.io.IOException: Unexpected exception
receiving call responses
at
org.apache.hadoop.hbase.ipc.HBaseClient.wrapException(HBaseClient.java:934)
at org.apache.hadoop.hbase.ipc.HBaseClient.call(HBaseClient.java:903)
at
org.apache.hadoop.hbase.ipc.WritableRpcEngine$Invoker.invoke(WritableRpcEngine.java:150)
at $Proxy6.close(Unknown Source)
at
org.apache.hadoop.hbase.client.ScannerCallable.close(ScannerCallable.java:112)
at
org.apache.hadoop.hbase.client.ScannerCallable.call(ScannerCallable.java:74)
at
org.apache.hadoop.hbase.client.ScannerCallable.call(ScannerCallable.java:39)
at
org.apache.hadoop.hbase.client.HConnectionManager$HConnectionImplementation.getRegionServerWithRetries(HConnectionManager.java:1325)
at
org.apache.hadoop.hbase.client.HTable$ClientScanner.nextScanner(HTable.java:1167)
at
org.apache.hadoop.hbase.client.HTable$ClientScanner.next(HTable.java:1296)
at
org.apache.hadoop.hbase.client.HTable$ClientScanner$1.hasNext(HTable.java:1356)
at
com.greatfree.hbase.rank.NodeRankRetriever.loadNodeGroupNodeRankRowKeys(NodeRankRetriever.java:348)
at
com.greatfree.ranking.PersistNodeGroupNodeRanksThread.run(PersistNodeGroupNodeRanksThread.java:29)
at
java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886)
at
java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908)
at java.lang.Thread.run(Thread.java:662) Caused by:
java.io.IOException: Unexpected exception receiving call responses
at
org.apache.hadoop.hbase.ipc.HBaseClient$Connection.run(HBaseClient.java:509)
Caused by: java.lang.NullPointerException
at
org.apache.hadoop.hbase.io.HbaseObjectWritable.readObject(HbaseObjectWritable.java:521)
at
org.apache.hadoop.hbase.io.HbaseObjectWritable.readFields(HbaseObjectWritable.java:297)
at
org.apache.hadoop.hbase.ipc.HBaseClient$Connection.receiveResponse(HBaseClient.java:593)
at
org.apache.hadoop.hbase.ipc.HBaseClient$Connection.run(HBaseClient.java:505)
I read data from HBase concurrently with the following code.
...
ExecutorService threadPool = Executors.newFixedThreadPool(100);
LoadNodeGroupNodeRankRowKeyThread thread;
Set<String> groupKeys;
for (String nodeKey : nodeKeys)
{
groupKeys = NodeCache.WWW().getGroupKeys(nodeKey);
for (String groupKey : groupKeys)
{
// Threads are initialized and executed here.
thread = new
LoadNodeGroupNodeRankRowKeyThread(nodeKey, groupKey,
TimingScale.PERMANENTLY);
threadPool.execute(thread);
}
}
Scanner in = new Scanner(System.in);
in.nextLine();
threadPool.shutdownNow();
...
The code of LoadNodeGroupNodeRankRowKeyThread is as follows,
...
public void run()
{
NodeRankRetriever retriever = new NodeRankRetriever();
Set<String> rowKeys =
retriever.loadNodeGroupNodeRankRowKeys(this.hostNodeKey,
this.groupKey, this.timingScale);
if (rowKeys.size() > 0)
{
for (String rowKey : rowKeys)
{
System.out.println(rowKey);
}
}
else
{
System.out.println("No data loaded");
}
retriever.dispose();
}
...
The constructor of NodeRankRetriever() just got an instance of HTable
from HTablePool from the following method.
...
public HTableInterface getTable(String tableName)
{
return this.hTablePool.getTable(tableName);
}
...
The method dispose() of NodeRankRetriever() just close the
HTableInterface created by HTablePool.
...
public void dispose()
{
try
{
this.rankTable.close();
}
catch (IOException e)
{
e.printStackTrace();
}
}
...
