Hadoop 1.2.1 - 多节点集群 - 对于Wordcount程序，Reducer阶段挂起？

时间：2015-09-10 20:44:12

标签： java hadoop mapreduce word-count

我的问题可能听起来多余，但早期问题的解决方案都是临时性的。很少有人尝试但没有运气。

Acutally，我正在研究hadoop-1.2.1（在ubuntu 14上），最初我有single node set-up，在那里我成功运行了WordCount程序。然后我根据this教程向它添加了一个节点。它成功启动，没有任何错误，但现在当我运行相同的WordCount程序时，它处于还原阶段。我查看了任务跟踪器日志，它们如下所示： - 

INFO org.apache.hadoop.mapred.TaskTracker: LaunchTaskAction (registerTask): attempt_201509110037_0001_m_000002_0 task's state:UNASSIGNED
INFO org.apache.hadoop.mapred.TaskTracker: Trying to launch : attempt_201509110037_0001_m_000002_0 which needs 1 slots
INFO org.apache.hadoop.mapred.TaskTracker: In TaskLauncher, current free slots : 2 and trying to launch attempt_201509110037_0001_m_000002_0 which needs 1 slots
INFO org.apache.hadoop.mapred.JobLocalizer: Initializing user hadoopuser on this TT.
INFO org.apache.hadoop.mapred.JvmManager: In JvmRunner constructed JVM ID: jvm_201509110037_0001_m_18975496
INFO org.apache.hadoop.mapred.JvmManager: JVM Runner jvm_201509110037_0001_m_18975496 spawned.
INFO org.apache.hadoop.mapred.TaskController: Writing commands to /app/hadoop/tmp/mapred/local/ttprivate/taskTracker/hadoopuser/jobcache/job_201509110037_0001/attempt_201509110037_0001_m_000002_0/taskjvm.sh
INFO org.apache.hadoop.mapred.TaskTracker: JVM with ID: jvm_201509110037_0001_m_18975496 given task: attempt_201509110037_0001_m_000002_0
INFO org.apache.hadoop.mapred.TaskTracker: attempt_201509110037_0001_m_000002_0 0.0% hdfs://HadoopMaster:54310/input/file02:25+3
INFO org.apache.hadoop.mapred.TaskTracker: Task attempt_201509110037_0001_m_000002_0 is done.
INFO org.apache.hadoop.mapred.TaskTracker: reported output size for attempt_201509110037_0001_m_000002_0  was 6
INFO org.apache.hadoop.mapred.TaskTracker: addFreeSlot : current free slots : 2
INFO org.apache.hadoop.mapred.JvmManager: JVM : jvm_201509110037_0001_m_18975496 exited with exit code 0. Number of tasks it ran: 1
INFO org.apache.hadoop.mapred.TaskTracker: LaunchTaskAction (registerTask): attempt_201509110037_0001_r_000000_0 task's state:UNASSIGNED
INFO org.apache.hadoop.mapred.TaskTracker: Trying to launch : attempt_201509110037_0001_r_000000_0 which needs 1 slots
INFO org.apache.hadoop.mapred.TaskTracker: In TaskLauncher, current free slots : 2 and trying to launch attempt_201509110037_0001_r_000000_0 which needs 1 slots
INFO org.apache.hadoop.io.nativeio.NativeIO: Initialized cache for UID to User mapping with a cache timeout of 14400 seconds.
INFO org.apache.hadoop.io.nativeio.NativeIO: Got UserName hadoopuser for UID 10 from the native implementation
INFO org.apache.hadoop.mapred.JvmManager: In JvmRunner constructed JVM ID: jvm_201509110037_0001_r_18975496
INFO org.apache.hadoop.mapred.JvmManager: JVM Runner jvm_201509110037_0001_r_18975496 spawned.
INFO org.apache.hadoop.mapred.TaskController: Writing commands to /app/hadoop/tmp/mapred/local/ttprivate/taskTracker/hadoopuser/jobcache/job_201509110037_0001/attempt_201509110037_0001_r_000000_0/taskjvm.sh
INFO org.apache.hadoop.mapred.TaskTracker: JVM with ID: jvm_201509110037_0001_r_18975496 given task: attempt_201509110037_0001_r_000000_0
INFO org.apache.hadoop.mapred.TaskTracker.clienttrace: src: 127.0.1.1:500, dest: 127.0.0.1:55946, bytes: 6, op: MAPRED_SHUFFLE, cliID: attempt_201509110037_0001_m_000002_0, duration: 7129894
INFO org.apache.hadoop.mapred.TaskTracker: attempt_201509110037_0001_r_000000_0 0.11111112% reduce > copy (1 of 3 at 0.00 MB/s) > 
INFO org.apache.hadoop.mapred.TaskTracker: attempt_201509110037_0001_r_000000_0 0.11111112% reduce > copy (1 of 3 at 0.00 MB/s) > 
INFO org.apache.hadoop.mapred.TaskTracker: attempt_201509110037_0001_r_000000_0 0.11111112% reduce > copy (1 of 3 at 0.00 MB/s) > 
INFO org.apache.hadoop.mapred.TaskTracker: attempt_201509110037_0001_r_000000_0 0.11111112% reduce > copy (1 of 3 at 0.00 MB/s) > 
INFO org.apache.hadoop.mapred.TaskTracker: attempt_201509110037_0001_r_000000_0 0.11111112% reduce > copy (1 of 3 at 0.00 MB/s) > 
INFO org.apache.hadoop.mapred.TaskTracker: attempt_201509110037_0001_r_000000_0 0.11111112% reduce > copy (1 of 3 at 0.00 MB/s) >

同样在我运行程序的控制台上，它挂起 - 

00:39:24 WARN mapred.JobClient: Use GenericOptionsParser for parsing the arguments. Applications should implement Tool for the same.
00:39:24 INFO util.NativeCodeLoader: Loaded the native-hadoop library
00:39:24 WARN snappy.LoadSnappy: Snappy native library not loaded
00:39:24 INFO mapred.FileInputFormat: Total input paths to process : 2
00:39:24 INFO mapred.JobClient: Running job: job_201509110037_0001
00:39:25 INFO mapred.JobClient:  map 0% reduce 0%
00:39:28 INFO mapred.JobClient:  map 100% reduce 0%
00:39:35 INFO mapred.JobClient:  map 100% reduce 11%

我的配置文件如下： -

//芯-site.xml中 

<configuration>
<property>
  <name>hadoop.tmp.dir</name>
  <value>/app/hadoop/tmp</value>
  <description>A base for other temporary directories.</description>
</property>

<property>
  <name>fs.default.name</name>
  <value>hdfs://HadoopMaster:54310</value>
  <description>The name of the default file system.  A URI whose
  scheme and authority determine the FileSystem implementation.  The
  uri's scheme determines the config property (fs.SCHEME.impl) naming
  the FileSystem implementation class.  The uri's authority is used to
  determine the host, port, etc. for a filesystem.</description>
</property>
</configuration>

// HDFS-site.xml中 

<configuration>
<property>
  <name>dfs.replication</name>
  <value>1</value>
  <description>Default block replication.
  The actual number of replications can be specified when the file is created.
  The default is used if replication is not specified in create time.
  </description>
</property>   
</configuration>

// mapred-site.xml中 

<configuration>
<property>
  <name>mapred.job.tracker</name>
  <value>HadoopMaster:54311</value>
  <description>The host and port that the MapReduce job tracker runs
  at.  If "local", then jobs are run in-process as a single map
  and reduce task.
  </description>
</property>
<property>
<name>mapred.reduce.slowstart.completed.maps</name>
  <value>0.80</value>
</property>    
</configuration>

的/ etc /主机 

127.0.0.1 localhost
127.0.1.1 M-1947

#HADOOP CLUSTER SETUP
172.50.88.54 HadoopMaster
172.50.88.60 HadoopSlave1

# The following lines are desirable for IPv6 capable hosts
::1     ip6-localhost ip6-loopback
fe00::0 ip6-localnet
ff00::0 ip6-mcastprefix
ff02::1 ip6-allnodes
ff02::2 ip6-allrouters

的/ etc /主机名

  

M-1947

//主人

  

HadoopMaster

//从站

  

HadoopMaster

     

HadoopSlave1

我一直在苦苦挣扎，任何帮助都表示赞赏。谢谢！

1 个答案:

答案 0 :(得分：1)

解决了问题..虽然，同样的问题在论坛上有多个问题，但根据我的验证解决方案是群集中任何节点的主机名解析应该是正确的（此外这个问题不依赖于大小簇）。

实际上这是 dns-lookup 的问题，请确保进行以下更改以解决上述问题 -

  1. 尝试使用'$ hostname'

    2. 在每台计算机上打印主机名

  2. 检查为每台机器打印的主机名是否与各机器的主/从文件中的条目相同。

  3. 如果不匹配，则通过在/ etc / hostname文件中进行更改并重新启动系统来重命名主机。

    4. 示例： -

    / etc / hosts 文件中的

    （假设在hadoop群集的主机上）

      

    127.0.0.1 localhost

         

    127.0.1.1 john-machine

         

    #Hadoop群集

         

    172.50.88.21 HadoopMaster

         

    172.50.88.22 HadoopSlave1

         

    172.50.88.23 HadoopSlave2

    然后是 - ＆gt; / etc / hostname file （在主机上）应包含以下条目（以解决上述问题）

      

    HadoopMaster

    同样验证每个从属节点的/ etc / hostname文件。

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