No. The key is generated randomly. In theory, it shall distributed to
all the RSs equally.

Thanks
Weihua

2011/5/17 Ted Dunning <[email protected]>:
> Are your keys arranged so that you have a problem with a hot region?
>
> On Mon, May 16, 2011 at 11:18 PM, Weihua JIANG <[email protected]>wrote:
>
>> I have not applied hdfs-347, but done some other experiments.
>>
>> I increased client thread to 2000 to put enough pressure on cluster. I
>> disabled RS block cache. The total TPS is still low (with Month+User
>> as row key, it is about 1300 for 10 RS+DN and with User+Month it is
>> 700).
>>
>> I used BTrace to log the time spent on each HTable.get on RS. It shows
>> that most of the GETs use 20~50ms and there are many GETs need
>> >1000ms. And almost all these times are spent on DFSClient$BlockReader
>> to read data from DN. But, the network usage is not high (<100Mb/s, we
>> have a giganet), so network is not a problem.
>>
>> Since for each DFS block read, there is a socket connection created. I
>> use netstat to caculate the TCP connections on 50010 port (DN listen
>> port) for each RS+DN server. It shows that there are always one or two
>> DNs have high such connection number (>200) while other DNs have low
>> number (<20). And the high connection DNs have high disk I/O usage
>> (about 100%) while other DNs have low disk I/O.  This phenoma lasts
>> for days and the hot machine is always the hot one.
>>
>> The high connection number mainly comes from local region server
>> request (~80%).
>>
>> According to the source code of DFSClient, it prefers to use local DN
>> to fetch block. But, why certain machine is so popular? All my servers
>> have almost the same configuration.
>>
>> 2011/4/29 Stack <[email protected]>:
>> > Yes, you could try applying hdfs-347 to your hdfs as J-D suggests.  Do
>> > your numbers change if you run your client from more than one machine?
>> > St.Ack
>> >
>> > On Thu, Apr 28, 2011 at 2:56 PM, Jean-Daniel Cryans <[email protected]>
>> wrote:
>> >> Seems to be a case of HDFS-347.
>> >>
>> >> J-D
>> >>
>> >> On Thu, Apr 28, 2011 at 12:55 AM, Weihua JIANG <[email protected]>
>> wrote:
>> >>> After solving HBASE-3561, I successfully run hprof for RS and DN.
>> >>> Since block cache is useless in my case, I disabled it. I rerun my
>> >>> test with 14 RS+DNs and 1 client with 200 threads. But, the throughput
>> >>> is still only about 700. No scalability shown in this case.
>> >>>
>> >>> Below is the hot spots in RS:
>> >>> CPU SAMPLES BEGIN (total = 1469756) Thu Apr 28 15:43:35 2011
>> >>> rank   self  accum   count trace method
>> >>>   1 44.33% 44.33%  651504 300612 sun.nio.ch.EPollArrayWrapper.epollWait
>> >>>   2 19.88% 64.21%  292221 301351 sun.nio.ch.EPollArrayWrapper.epollWait
>> >>>   3  8.88% 73.09%  130582 300554 sun.nio.ch.EPollArrayWrapper.epollWait
>> >>>   4  4.43% 77.52%   65106 301248 sun.nio.ch.EPollArrayWrapper.epollWait
>> >>>   5  4.43% 81.95%   65104 301249 sun.nio.ch.EPollArrayWrapper.epollWait
>> >>>   6  4.43% 86.38%   65100 301247 sun.nio.ch.EPollArrayWrapper.epollWait
>> >>>   7  4.43% 90.81%   65061 301266 sun.nio.ch.EPollArrayWrapper.epollWait
>> >>>   8  4.32% 95.13%   63465 301565 sun.nio.ch.EPollArrayWrapper.epollWait
>> >>>   9  2.31% 97.43%   33894 301555 sun.nio.ch.EPollArrayWrapper.epollWait
>> >>>  10  1.76% 99.19%   25841 301588 sun.nio.ch.EPollArrayWrapper.epollWait
>> >>>  11  0.48% 99.67%    7025 301443sun.nio.ch.EPollArrayWrapper.epollWait
>> >>>  12  0.02% 99.69%     341 301568 sun.nio.ch.NativeThread.current
>> >>>  13  0.01% 99.71%     187 301535
>> >>> org.apache.hadoop.hbase.io.hfile.HFile$Reader.indexSize
>> >>>  14  0.01% 99.72%     186 301538
>> >>> org.apache.hadoop.hbase.io.hfile.HFile$Reader.indexSize
>> >>>  15  0.01% 99.73%     170 301625
>> org.apache.hadoop.util.DataChecksum.update
>> >>>  16  0.01% 99.74%     164 301579 sun.nio.ch.EPollArrayWrapper.epollWait
>> >>>  17  0.01% 99.75%     149 300938 sun.nio.ch.EPollArrayWrapper.epollWait
>> >>>
>> >>> TRACE 300612:
>> >>>
>>  sun.nio.ch.EPollArrayWrapper.epollWait(EPollArrayWrapper.java:Unknown line)
>> >>>        sun.nio.ch.EPollArrayWrapper.poll(EPollArrayWrapper.java:215)
>> >>>        sun.nio.ch.EPollSelectorImpl.doSelect(EPollSelectorImpl.java:65)
>> >>>        sun.nio.ch.SelectorImpl.lockAndDoSelect(SelectorImpl.java:69)
>> >>>        sun.nio.ch.SelectorImpl.select(SelectorImpl.java:80)
>> >>>        sun.nio.ch.SelectorImpl.select(SelectorImpl.java:84)
>> >>>
>>  org.apache.hadoop.hbase.ipc.HBaseServer$Listener$Reader.run(HBaseServer.java:305)
>> >>>
>>  java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886)
>> >>>
>>  java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908)
>> >>>        java.lang.Thread.run(Thread.java:619)
>> >>> TRACE 301351:
>> >>>
>>  sun.nio.ch.EPollArrayWrapper.epollWait(EPollArrayWrapper.java:Unknown line)
>> >>>        sun.nio.ch.EPollArrayWrapper.poll(EPollArrayWrapper.java:215)
>> >>>        sun.nio.ch.EPollSelectorImpl.doSelect(EPollSelectorImpl.java:65)
>> >>>        sun.nio.ch.SelectorImpl.lockAndDoSelect(SelectorImpl.java:69)
>> >>>        sun.nio.ch.SelectorImpl.select(SelectorImpl.java:80)
>> >>>
>>  org.apache.hadoop.net.SocketIOWithTimeout$SelectorPool.select(SocketIOWithTimeout.java:332)
>> >>>
>>  org.apache.hadoop.net.SocketIOWithTimeout.doIO(SocketIOWithTimeout.java:157)
>> >>>
>>  org.apache.hadoop.net.SocketInputStream.read(SocketInputStream.java:155)
>> >>>
>>  org.apache.hadoop.net.SocketInputStream.read(SocketInputStream.java:128)
>> >>>        java.io.BufferedInputStream.fill(BufferedInputStream.java:218)
>> >>>        java.io.BufferedInputStream.read1(BufferedInputStream.java:258)
>> >>>        java.io.BufferedInputStream.read(BufferedInputStream.java:317)
>> >>>        java.io.DataInputStream.read(DataInputStream.java:132)
>> >>>        org.apache.hadoop.io.IOUtils.readFully(IOUtils.java:102)
>> >>>
>>  org.apache.hadoop.hdfs.DFSClient$BlockReader.readChunk(DFSClient.java:1389)
>> >>>
>>  org.apache.hadoop.fs.FSInputChecker.readChecksumChunk(FSInputChecker.java:237)
>> >>>
>>  org.apache.hadoop.fs.FSInputChecker.fill(FSInputChecker.java:176)
>> >>>
>>  org.apache.hadoop.fs.FSInputChecker.read1(FSInputChecker.java:193)
>> >>>
>>  org.apache.hadoop.fs.FSInputChecker.read(FSInputChecker.java:158)
>> >>>
>>  org.apache.hadoop.hdfs.DFSClient$BlockReader.read(DFSClient.java:1243)
>> >>> TRACE 300554:
>> >>>
>>  sun.nio.ch.EPollArrayWrapper.epollWait(EPollArrayWrapper.java:Unknown line)
>> >>>        sun.nio.ch.EPollArrayWrapper.poll(EPollArrayWrapper.java:215)
>> >>>        sun.nio.ch.EPollSelectorImpl.doSelect(EPollSelectorImpl.java:65)
>> >>>        sun.nio.ch.SelectorImpl.lockAndDoSelect(SelectorImpl.java:69)
>> >>>        sun.nio.ch.SelectorImpl.select(SelectorImpl.java:80)
>> >>>
>>  org.apache.zookeeper.ClientCnxn$SendThread.run(ClientCnxn.java:1107)
>> >>> TRACE 301248:
>> >>>
>>  sun.nio.ch.EPollArrayWrapper.epollWait(EPollArrayWrapper.java:Unknown line)
>> >>>        sun.nio.ch.EPollArrayWrapper.poll(EPollArrayWrapper.java:215)
>> >>>        sun.nio.ch.EPollSelectorImpl.doSelect(EPollSelectorImpl.java:65)
>> >>>        sun.nio.ch.SelectorImpl.lockAndDoSelect(SelectorImpl.java:69)
>> >>>        sun.nio.ch.SelectorImpl.select(SelectorImpl.java:80)
>> >>>
>>  org.apache.hadoop.hbase.ipc.HBaseServer$Responder.run(HBaseServer.java:588)
>> >>> TRACE 301249:
>> >>>
>>  sun.nio.ch.EPollArrayWrapper.epollWait(EPollArrayWrapper.java:Unknown line)
>> >>>        sun.nio.ch.EPollArrayWrapper.poll(EPollArrayWrapper.java:215)
>> >>>        sun.nio.ch.EPollSelectorImpl.doSelect(EPollSelectorImpl.java:65)
>> >>>        sun.nio.ch.SelectorImpl.lockAndDoSelect(SelectorImpl.java:69)
>> >>>        sun.nio.ch.SelectorImpl.select(SelectorImpl.java:80)
>> >>>        sun.nio.ch.SelectorImpl.select(SelectorImpl.java:84)
>> >>>
>>  org.apache.hadoop.hbase.ipc.HBaseServer$Listener.run(HBaseServer.java:414)
>> >>> TRACE 301247:
>> >>>
>>  sun.nio.ch.EPollArrayWrapper.epollWait(EPollArrayWrapper.java:Unknown line)
>> >>>        sun.nio.ch.EPollArrayWrapper.poll(EPollArrayWrapper.java:215)
>> >>>        sun.nio.ch.EPollSelectorImpl.doSelect(EPollSelectorImpl.java:65)
>> >>>        sun.nio.ch.SelectorImpl.lockAndDoSelect(SelectorImpl.java:69)
>> >>>        sun.nio.ch.SelectorImpl.select(SelectorImpl.java:80)
>> >>>
>>  org.mortbay.io.nio.SelectorManager$SelectSet.doSelect(SelectorManager.java:498)
>> >>>
>>  org.mortbay.io.nio.SelectorManager.doSelect(SelectorManager.java:192)
>> >>>
>>  org.mortbay.jetty.nio.SelectChannelConnector.accept(SelectChannelConnector.java:124)
>> >>>
>>  org.mortbay.jetty.AbstractConnector$Acceptor.run(AbstractConnector.java:708)
>> >>>
>>  org.mortbay.thread.QueuedThreadPool$PoolThread.run(QueuedThreadPool.java:582)
>> >>> TRACE 301266:
>> >>>
>>  sun.nio.ch.EPollArrayWrapper.epollWait(EPollArrayWrapper.java:Unknown line)
>> >>>        sun.nio.ch.EPollArrayWrapper.poll(EPollArrayWrapper.java:215)
>> >>>        sun.nio.ch.EPollSelectorImpl.doSelect(EPollSelectorImpl.java:65)
>> >>>        sun.nio.ch.SelectorImpl.lockAndDoSelect(SelectorImpl.java:69)
>> >>>        sun.nio.ch.SelectorImpl.select(SelectorImpl.java:80)
>> >>>
>>  org.apache.hadoop.net.SocketIOWithTimeout$SelectorPool.select(SocketIOWithTimeout.java:332)
>> >>>
>>  org.apache.hadoop.net.SocketIOWithTimeout.doIO(SocketIOWithTimeout.java:157)
>> >>>
>>  org.apache.hadoop.net.SocketInputStream.read(SocketInputStream.java:155)
>> >>>
>>  org.apache.hadoop.net.SocketInputStream.read(SocketInputStream.java:128)
>> >>>        java.io.DataInputStream.readFully(DataInputStream.java:178)
>> >>>        java.io.DataInputStream.readLong(DataInputStream.java:399)
>> >>>
>>  org.apache.hadoop.hdfs.protocol.DataTransferProtocol$PipelineAck.readFields(DataTransferProtocol.java:120)
>> >>>
>>  org.apache.hadoop.hdfs.DFSClient$DFSOutputStream$ResponseProcessor.run(DFSClient.java:2638)
>> >>> TRACE 301565:
>> >>>
>>  sun.nio.ch.EPollArrayWrapper.epollWait(EPollArrayWrapper.java:Unknown line)
>> >>>        sun.nio.ch.EPollArrayWrapper.poll(EPollArrayWrapper.java:215)
>> >>>        sun.nio.ch.EPollSelectorImpl.doSelect(EPollSelectorImpl.java:65)
>> >>>        sun.nio.ch.SelectorImpl.lockAndDoSelect(SelectorImpl.java:69)
>> >>>        sun.nio.ch.SelectorImpl.select(SelectorImpl.java:80)
>> >>>
>>  org.apache.hadoop.net.SocketIOWithTimeout$SelectorPool.select(SocketIOWithTimeout.java:332)
>> >>>
>>  org.apache.hadoop.net.SocketIOWithTimeout.doIO(SocketIOWithTimeout.java:157)
>> >>>
>>  org.apache.hadoop.net.SocketInputStream.read(SocketInputStream.java:155)
>> >>>
>>  org.apache.hadoop.net.SocketInputStream.read(SocketInputStream.java:128)
>> >>>        java.io.BufferedInputStream.fill(BufferedInputStream.java:218)
>> >>>        java.io.BufferedInputStream.read1(BufferedInputStream.java:258)
>> >>>        java.io.BufferedInputStream.read(BufferedInputStream.java:317)
>> >>>        java.io.DataInputStream.read(DataInputStream.java:132)
>> >>>        org.apache.hadoop.io.IOUtils.readFully(IOUtils.java:102)
>> >>>
>>  org.apache.hadoop.hdfs.DFSClient$BlockReader.readChunk(DFSClient.java:1389)
>> >>>
>>  org.apache.hadoop.fs.FSInputChecker.readChecksumChunk(FSInputChecker.java:237)
>> >>>
>>  org.apache.hadoop.fs.FSInputChecker.read1(FSInputChecker.java:189)
>> >>>
>>  org.apache.hadoop.fs.FSInputChecker.read(FSInputChecker.java:158)
>> >>>
>>  org.apache.hadoop.hdfs.DFSClient$BlockReader.read(DFSClient.java:1249)
>> >>>
>>  org.apache.hadoop.fs.FSInputChecker.readFully(FSInputChecker.java:384)
>> >>>
>> >>>
>> >>> And the hot spot of DN is:
>> >>> CPU SAMPLES BEGIN (total = 1123925) Thu Apr 28 15:43:49 2011
>> >>> rank   self  accum   count trace method
>> >>>   1 12.38% 12.38%  139155 301547 sun.nio.ch.EPollArrayWrapper.epollWait
>> >>>   2 12.38% 24.76%  139154 301548 sun.nio.ch.EPollArrayWrapper.epollWait
>> >>>   3 10.76% 35.53%  120969 300368 java.net.PlainSocketImpl.socketAccept
>> >>>   4 10.74% 46.27%  120753 301213 sun.nio.ch.EPollArrayWrapper.epollWait
>> >>>   5 10.74% 57.01%  120744 301381 sun.nio.ch.EPollArrayWrapper.epollWait
>> >>>   6 10.74% 67.76%  120744 301384 sun.nio.ch.EPollArrayWrapper.epollWait
>> >>>   7 10.74% 78.50%  120743 301386 sun.nio.ch.EPollArrayWrapper.epollWait
>> >>>   8 10.68% 89.18%  120019 301383
>> sun.nio.ch.ServerSocketChannelImpl.accept0
>> >>>   9  8.11% 97.29%   91174 301475 sun.nio.ch.FileChannelImpl.transferTo0
>> >>>  10  1.44% 98.73%   16172 301479 java.io.FileInputStream.readBytes
>> >>>  11  0.40% 99.13%    4496 301477 java.io.FileInputStream.readBytes
>> >>>  12  0.23% 99.35%    2531 301497 sun.nio.ch.EPollArrayWrapper.epollWait
>> >>>  13  0.17% 99.53%    1958 301461 java.io.FileInputStream.readBytes
>> >>>  14  0.04% 99.57%     458 301468 java.io.UnixFileSystem.delete0
>> >>>  15  0.03% 99.59%     289 301520 java.lang.Thread.start0
>> >>>  16  0.02% 99.62%     278 301471
>> org.apache.hadoop.util.DataChecksum.update
>> >>>  17  0.02% 99.64%     204 301562
>> java.io.UnixFileSystem.getBooleanAttributes0
>> >>>  18  0.01% 99.65%     117 301587 sun.nio.ch.EPollArrayWrapper.epollCtl
>> >>>  19  0.01% 99.66%     113 301493 sun.nio.ch.FileDispatcher.write0
>> >>>
>> >>> TRACE 301547:
>> >>>
>>  sun.nio.ch.EPollArrayWrapper.epollWait(EPollArrayWrapper.java:Unknown line)
>> >>>        sun.nio.ch.EPollArrayWrapper.poll(EPollArrayWrapper.java:215)
>> >>>        sun.nio.ch.EPollSelectorImpl.doSelect(EPollSelectorImpl.java:65)
>> >>>        sun.nio.ch.SelectorImpl.lockAndDoSelect(SelectorImpl.java:69)
>> >>>        sun.nio.ch.SelectorImpl.select(SelectorImpl.java:80)
>> >>>
>>  org.apache.hadoop.net.SocketIOWithTimeout$SelectorPool.select(SocketIOWithTimeout.java:332)
>> >>>
>>  org.apache.hadoop.net.SocketIOWithTimeout.doIO(SocketIOWithTimeout.java:157)
>> >>>
>>  org.apache.hadoop.net.SocketInputStream.read(SocketInputStream.java:155)
>> >>>
>>  org.apache.hadoop.net.SocketInputStream.read(SocketInputStream.java:128)
>> >>>        java.io.BufferedInputStream.fill(BufferedInputStream.java:218)
>> >>>        java.io.BufferedInputStream.read1(BufferedInputStream.java:258)
>> >>>        java.io.BufferedInputStream.read(BufferedInputStream.java:317)
>> >>>        java.io.DataInputStream.read(DataInputStream.java:132)
>> >>>
>>  org.apache.hadoop.hdfs.server.datanode.BlockReceiver.readToBuf(BlockReceiver.java:267)
>> >>>
>>  org.apache.hadoop.hdfs.server.datanode.BlockReceiver.readNextPacket(BlockReceiver.java:314)
>> >>>
>>  org.apache.hadoop.hdfs.server.datanode.BlockReceiver.receivePacket(BlockReceiver.java:378)
>> >>>
>>  org.apache.hadoop.hdfs.server.datanode.BlockReceiver.receiveBlock(BlockReceiver.java:534)
>> >>>
>>  org.apache.hadoop.hdfs.server.datanode.DataXceiver.writeBlock(DataXceiver.java:417)
>> >>>
>>  org.apache.hadoop.hdfs.server.datanode.DataXceiver.run(DataXceiver.java:122)
>> >>> TRACE 301548:
>> >>>
>>  sun.nio.ch.EPollArrayWrapper.epollWait(EPollArrayWrapper.java:Unknown line)
>> >>>        sun.nio.ch.EPollArrayWrapper.poll(EPollArrayWrapper.java:215)
>> >>>        sun.nio.ch.EPollSelectorImpl.doSelect(EPollSelectorImpl.java:65)
>> >>>        sun.nio.ch.SelectorImpl.lockAndDoSelect(SelectorImpl.java:69)
>> >>>        sun.nio.ch.SelectorImpl.select(SelectorImpl.java:80)
>> >>>
>>  org.apache.hadoop.net.SocketIOWithTimeout$SelectorPool.select(SocketIOWithTimeout.java:332)
>> >>>
>>  org.apache.hadoop.net.SocketIOWithTimeout.doIO(SocketIOWithTimeout.java:157)
>> >>>
>>  org.apache.hadoop.net.SocketInputStream.read(SocketInputStream.java:155)
>> >>>
>>  org.apache.hadoop.net.SocketInputStream.read(SocketInputStream.java:128)
>> >>>        java.io.DataInputStream.readFully(DataInputStream.java:178)
>> >>>        java.io.DataInputStream.readLong(DataInputStream.java:399)
>> >>>
>>  org.apache.hadoop.hdfs.protocol.DataTransferProtocol$PipelineAck.readFields(DataTransferProtocol.java:120)
>> >>>
>>  org.apache.hadoop.hdfs.server.datanode.BlockReceiver$PacketResponder.run(BlockReceiver.java:894)
>> >>>        java.lang.Thread.run(Thread.java:619)
>> >>> TRACE 300368:
>> >>>
>>  java.net.PlainSocketImpl.socketAccept(PlainSocketImpl.java:Unknown line)
>> >>>        java.net.PlainSocketImpl.accept(PlainSocketImpl.java:390)
>> >>>        java.net.ServerSocket.implAccept(ServerSocket.java:453)
>> >>>        java.net.ServerSocket.accept(ServerSocket.java:421)
>> >>>
>>  sun.management.jmxremote.LocalRMIServerSocketFactory$1.accept(LocalRMIServerSocketFactory.java:34)
>> >>>
>>  sun.rmi.transport.tcp.TCPTransport$AcceptLoop.executeAcceptLoop(TCPTransport.java:369)
>> >>>
>>  sun.rmi.transport.tcp.TCPTransport$AcceptLoop.run(TCPTransport.java:341)
>> >>>        java.lang.Thread.run(Thread.java:619)
>> >>> TRACE 301213:
>> >>>
>>  sun.nio.ch.EPollArrayWrapper.epollWait(EPollArrayWrapper.java:Unknown line)
>> >>>        sun.nio.ch.EPollArrayWrapper.poll(EPollArrayWrapper.java:215)
>> >>>        sun.nio.ch.EPollSelectorImpl.doSelect(EPollSelectorImpl.java:65)
>> >>>        sun.nio.ch.SelectorImpl.lockAndDoSelect(SelectorImpl.java:69)
>> >>>        sun.nio.ch.SelectorImpl.select(SelectorImpl.java:80)
>> >>>
>>  org.mortbay.io.nio.SelectorManager$SelectSet.doSelect(SelectorManager.java:498)
>> >>>
>>  org.mortbay.io.nio.SelectorManager.doSelect(SelectorManager.java:192)
>> >>>
>>  org.mortbay.jetty.nio.SelectChannelConnector.accept(SelectChannelConnector.java:124)
>> >>>
>>  org.mortbay.jetty.AbstractConnector$Acceptor.run(AbstractConnector.java:708)
>> >>>
>>  org.mortbay.thread.QueuedThreadPool$PoolThread.run(QueuedThreadPool.java:582)
>> >>> TRACE 301381:
>> >>>
>>  sun.nio.ch.EPollArrayWrapper.epollWait(EPollArrayWrapper.java:Unknown line)
>> >>>        sun.nio.ch.EPollArrayWrapper.poll(EPollArrayWrapper.java:215)
>> >>>        sun.nio.ch.EPollSelectorImpl.doSelect(EPollSelectorImpl.java:65)
>> >>>        sun.nio.ch.SelectorImpl.lockAndDoSelect(SelectorImpl.java:69)
>> >>>        sun.nio.ch.SelectorImpl.select(SelectorImpl.java:80)
>> >>>        sun.nio.ch.SelectorImpl.select(SelectorImpl.java:84)
>> >>>
>>  org.apache.hadoop.ipc.Server$Listener$Reader.run(Server.java:352)
>> >>> TRACE 301384:
>> >>>
>>  sun.nio.ch.EPollArrayWrapper.epollWait(EPollArrayWrapper.java:Unknown line)
>> >>>        sun.nio.ch.EPollArrayWrapper.poll(EPollArrayWrapper.java:215)
>> >>>        sun.nio.ch.EPollSelectorImpl.doSelect(EPollSelectorImpl.java:65)
>> >>>        sun.nio.ch.SelectorImpl.lockAndDoSelect(SelectorImpl.java:69)
>> >>>        sun.nio.ch.SelectorImpl.select(SelectorImpl.java:80)
>> >>>        org.apache.hadoop.ipc.Server$Responder.run(Server.java:636)
>> >>> TRACE 301386:
>> >>>
>>  sun.nio.ch.EPollArrayWrapper.epollWait(EPollArrayWrapper.java:Unknown line)
>> >>>        sun.nio.ch.EPollArrayWrapper.poll(EPollArrayWrapper.java:215)
>> >>>        sun.nio.ch.EPollSelectorImpl.doSelect(EPollSelectorImpl.java:65)
>> >>>        sun.nio.ch.SelectorImpl.lockAndDoSelect(SelectorImpl.java:69)
>> >>>        sun.nio.ch.SelectorImpl.select(SelectorImpl.java:80)
>> >>>        sun.nio.ch.SelectorImpl.select(SelectorImpl.java:84)
>> >>>        org.apache.hadoop.ipc.Server$Listener.run(Server.java:468)
>> >>> TRACE 301383:
>> >>>
>>  sun.nio.ch.ServerSocketChannelImpl.accept0(ServerSocketChannelImpl.java:Unknown
>> >>> line)
>> >>>
>>  sun.nio.ch.ServerSocketChannelImpl.accept(ServerSocketChannelImpl.java:145)
>> >>>
>>  sun.nio.ch.ServerSocketAdaptor.accept(ServerSocketAdaptor.java:84)
>> >>>
>>  org.apache.hadoop.hdfs.server.datanode.DataXceiverServer.run(DataXceiverServer.java:130)
>> >>>        java.lang.Thread.run(Thread.java:619)
>> >>> TRACE 301475:
>> >>>
>>  sun.nio.ch.FileChannelImpl.transferTo0(FileChannelImpl.java:Unknown line)
>> >>>
>>  sun.nio.ch.FileChannelImpl.transferToDirectly(FileChannelImpl.java:415)
>> >>>        sun.nio.ch.FileChannelImpl.transferTo(FileChannelImpl.java:516)
>> >>>
>>  org.apache.hadoop.net.SocketOutputStream.transferToFully(SocketOutputStream.java:199)
>> >>>
>>  org.apache.hadoop.hdfs.server.datanode.BlockSender.sendChunks(BlockSender.java:350)
>> >>>
>>  org.apache.hadoop.hdfs.server.datanode.BlockSender.sendBlock(BlockSender.java:436)
>> >>>
>>  org.apache.hadoop.hdfs.server.datanode.DataXceiver.readBlock(DataXceiver.java:214)
>> >>>
>>  org.apache.hadoop.hdfs.server.datanode.DataXceiver.run(DataXceiver.java:114)
>> >>> TRACE 301479:
>> >>>        java.io.FileInputStream.readBytes(FileInputStream.java:Unknown
>> line)
>> >>>        java.io.FileInputStream.read(FileInputStream.java:199)
>> >>>        java.io.FilterInputStream.read(FilterInputStream.java:116)
>> >>>        java.io.BufferedInputStream.fill(BufferedInputStream.java:218)
>> >>>        java.io.BufferedInputStream.read1(BufferedInputStream.java:258)
>> >>>        java.io.BufferedInputStream.read(BufferedInputStream.java:317)
>> >>>        java.io.DataInputStream.readFully(DataInputStream.java:178)
>> >>>
>>  org.apache.hadoop.hdfs.server.datanode.BlockSender.sendChunks(BlockSender.java:271)
>> >>>
>>  org.apache.hadoop.hdfs.server.datanode.BlockSender.sendBlock(BlockSender.java:436)
>> >>>
>>  org.apache.hadoop.hdfs.server.datanode.DataXceiver.readBlock(DataXceiver.java:214)
>> >>>
>>  org.apache.hadoop.hdfs.server.datanode.DataXceiver.run(DataXceiver.java:114)
>> >>>
>> >>> Thanks
>> >>> Weihua
>> >>>
>> >>> 2011/4/28 Weihua JIANG <[email protected]>:
>> >>>> I am using CDH3U0. It is HBase 0.90.1, I think.
>> >>>>
>> >>>> Thanks
>> >>>> Weihua
>> >>>>
>> >>>> 2011/4/28 Stack <[email protected]>:
>> >>>>> On Tue, Apr 26, 2011 at 6:02 PM, Weihua JIANG <
>> [email protected]> wrote:
>> >>>>>> I tried to enable HPROF on RS, but failed. If I added the HPROF
>> agent
>> >>>>>> in hbase-env.sh, RS startup reports an error said HPROF can't be
>> >>>>>> loaded twice. But, I am sure I only enabled it once. I don't know
>> >>>>>> where the problem is.
>> >>>>>>
>> >>>>>
>> >>>>> This sounds like 'HBASE-3561  OPTS arguments are duplicated'  Are you
>> >>>>> running 0.90.2?
>> >>>>>
>> >>>>> St.Ack
>> >>>>>
>> >>>>
>> >>>
>> >>
>> >
>>
>

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