Looks like the issue might be related to HTable:
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$1.
hasNext(HTable.java:1356)
In newer version of HBase (0.94), you can pass executor to HTable ctor so
that you don't need to use HTablePool:
public HTable(Configuration conf, final byte[] tableName,
finalExecutorService pool)
Cheers
On Wed, Feb 6, 2013 at 2:27 AM, Bing Li <[email protected]> wrote:
> Dear all,
>
> Some exceptions are raised when I concurrently read data from HBase.
> The version of HBase I used is 0.92.0.
>
> I cannot fix the problem. Could you please help me?
>
> Thanks so much!
>
> Best wishes,
> Bing
>
> Feb 6, 2013 12:21:31 AM
> org.apache.hadoop.hbase.ipc.HBaseClient$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();
> }
> }
> ...
>
