Hadoop 1.2.1 - 多节点集群 - Wordcount 程序的 Reducer 阶段挂起？
Hadoop 1.2.1 - multinode cluster - Reducer phase hangs for Wordcount program?
我的问题在这里听起来可能是多余的，但对前面问题的解决方案都是临时的。我尝试过的很少，但还没有成功。
实际上，我正在研究 hadoop-1.2.1（在 ubuntu 14 上），最初我有 single node set-up and there I ran the WordCount program succesfully. Then I added one more node to it according to this 教程。它成功启动，没有任何错误，但是现在当我 运行 同一个 WordCount 程序时，它挂在 reduce 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) >
也在我所在的控制台上 运行 程序挂在 -
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:-
//核心-site.xml
<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
<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
<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>
/etc/hosts
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
/etc/hostname
M-1947
//高手
HadoopMaster
//奴隶
HadoopMaster
HadoopSlave1
我已经为此苦苦挣扎了很长时间，感谢您的帮助。谢谢！
解决了..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集群中任何节点的主机名解析应该是正确的（而且这个问题不依赖于簇的大小）。
实际上这是 dns-lookup 的问题，确保进行以下更改以解决上述问题 -
尝试在每台机器上使用“$ hostname”打印主机名
检查为每台机器打印的主机名是否与在相应机器的 master/slaves 文件中输入的条目相同。
- 如果不匹配，则通过在 /etc/hostname 文件中进行更改来重命名主机并重新启动系统。
示例：-
在/etc/hosts文件中（假设在hadoop集群的Master机器上）
127.0.0.1 localhost
127.0.1.1 john-machine
#Hadoop cluster
172.50.88.21 HadoopMaster
172.50.88.22 HadoopSlave1
172.50.88.23 HadoopSlave2
那么它是 -> /etc/hostname 文件（在主机上）应该包含以下条目（为了解决上述问题）
HadoopMaster
同样验证每个slave节点的/etc/hostname个文件
我的问题在这里听起来可能是多余的，但对前面问题的解决方案都是临时的。我尝试过的很少，但还没有成功。
实际上，我正在研究 hadoop-1.2.1（在 ubuntu 14 上），最初我有 single node set-up and there I ran the WordCount program succesfully. Then I added one more node to it according to this 教程。它成功启动，没有任何错误，但是现在当我 运行 同一个 WordCount 程序时，它挂在 reduce 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) >
也在我所在的控制台上 运行 程序挂在 -
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:-
//核心-site.xml
<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
<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
<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>
/etc/hosts
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
/etc/hostname
M-1947
//高手
HadoopMaster
//奴隶
HadoopMaster
HadoopSlave1
我已经为此苦苦挣扎了很长时间，感谢您的帮助。谢谢！
解决了..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集群中任何节点的主机名解析应该是正确的（而且这个问题不依赖于簇的大小）。
实际上这是 dns-lookup 的问题，确保进行以下更改以解决上述问题 -
尝试在每台机器上使用“$ hostname”打印主机名
检查为每台机器打印的主机名是否与在相应机器的 master/slaves 文件中输入的条目相同。
- 如果不匹配，则通过在 /etc/hostname 文件中进行更改来重命名主机并重新启动系统。
示例：-
在/etc/hosts文件中（假设在hadoop集群的Master机器上）
127.0.0.1 localhost
127.0.1.1 john-machine
#Hadoop cluster
172.50.88.21 HadoopMaster
172.50.88.22 HadoopSlave1
172.50.88.23 HadoopSlave2
那么它是 -> /etc/hostname 文件（在主机上）应该包含以下条目（为了解决上述问题）
HadoopMaster
同样验证每个slave节点的/etc/hostname个文件