我正在尝试在Hadoop集群上启动H2O。遗憾的是，它不起作用，并给我一个错误，即找不到类water.hadoop.h2omapper。
Hadoop环境是2.6版本中的HDP，包括5个节点，其中1个运行YARN资源管理器，3个节点是YARN客户端的数据节点。每个数据节点具有32GB RAM和4个CPU核心的资源。没有其他应用程序在其上运行。我在Ambari的每个节点上为每个YARN应用程序配置了最多16GB和3个内核。
我从终端启动H2O集群(在所有节点上都尝试过，到处都有相同的错误)，输出如下：
[root@host3 h2o-3.14.0.6-hdp2.6]# sudo -u hdfs hadoop jar h2odriver.jar -nodes 3 -mapperXmx 6g -output h2o-test
Determining driver host interface for mapper->driver callback...
[Possible callback IP address: 192.168.20.35]
[Possible callback IP address: 127.0.0.1]
Using mapper->driver callback IP address and port: 192.168.20.35:46619
(You can override these with -driverif and -driverport/-driverportrange.)
Memory Settings:
mapreduce.map.java.opts: -Xms6g -Xmx6g -verbose:gc -XX:+PrintGCDetails -XX:+PrintGCTimeStamps -Dlog4j.defaultInitOverride=true
Extra memory percent: 10
mapreduce.map.memory.mb: 6758
17/10/13 07:49:14 INFO client.RMProxy: Connecting to ResourceManager at host2/192.168.20.34:8050
17/10/13 07:49:14 INFO client.AHSProxy: Connecting to Application History server at host2/192.168.20.34:10200
17/10/13 07:49:15 WARN mapreduce.JobResourceUploader: No job jar file set. User classes may not be found. See Job or Job#setJar(String).
17/10/13 07:49:15 INFO mapreduce.JobSubmitter: number of splits:3
17/10/13 07:49:15 INFO mapreduce.JobSubmitter: Submitting tokens for job: job_1507793796947_0002
17/10/13 07:49:15 INFO mapred.YARNRunner: Job jar is not present. Not adding any jar to the list of resources.
17/10/13 07:49:15 INFO impl.YarnClientImpl: Submitted application application_1507793796947_0002
17/10/13 07:49:15 INFO mapreduce.Job: The url to track the job: http://host2:8088/proxy/application_1507793796947_0002/
Job name 'H2O_86929' submitted
JobTracker job ID is 'job_1507793796947_0002'
For YARN users, logs command is 'yarn logs -applicationId application_1507793796947_0002'
Waiting for H2O cluster to come up...
17/10/13 07:49:29 INFO client.RMProxy: Connecting to ResourceManager at host2/192.168.20.34:8050
17/10/13 07:49:29 INFO client.AHSProxy: Connecting to Application History server at host2/192.168.20.34:10200
----- YARN cluster metrics -----
Number of YARN worker nodes: 3
----- Nodes -----
Node: http://host5:8042 Rack: /default-rack, RUNNING, 1 containers used, 4,0 / 16,0 GB used, 1 / 3 vcores used
Node: http://host4:8042 Rack: /default-rack, RUNNING, 0 containers used, 0,0 / 16,0 GB used, 0 / 3 vcores used
Node: http://host3:8042 Rack: /default-rack, RUNNING, 0 containers used, 0,0 / 16,0 GB used, 0 / 3 vcores used
----- Queues -----
Queue name: default
Queue state: RUNNING
Current capacity: 0,11
Capacity: 1,00
Maximum capacity: 1,00
Application count: 1
----- Applications in this queue -----
Application ID: application_1507793796947_0002 (H2O_86929)
Started: hdfs (Fri Oct 13 07:49:15 CEST 2017)
Application state: FINISHED
Tracking URL: http://host2:8088/proxy/application_1507793796947_0002/
Queue name: default
Used/Reserved containers: 1 / 0
Needed/Used/Reserved memory: 4,0 GB / 4,0 GB / 0,0 GB
Needed/Used/Reserved vcores: 1 / 1 / 0
Queue 'default' approximate utilization: 4,0 / 48,0 GB used, 1 / 9 vcores used
----------------------------------------------------------------------
ERROR: Unable to start any H2O nodes; please contact your YARN administrator.
A common cause for this is the requested container size (6,6 GB)
exceeds the following YARN settings:
yarn.nodemanager.resource.memory-mb
yarn.scheduler.maximum-allocation-mb
Yarn应用程序的系统日志中的相应错误条目：
2017-10-13 07:49:24,505 FATAL [IPC Server handler 1 on 40503] org.apache.hadoop.mapred.TaskAttemptListenerImpl: Task: attempt_1507793796947_0002_m_000002_0 - exited : java.lang.RuntimeException: java.lang.ClassNotFoundException: Class water.hadoop.h2omapper not found
at org.apache.hadoop.conf.Configuration.getClass(Configuration.java:2241)
at org.apache.hadoop.mapreduce.task.JobContextImpl.getMapperClass(JobContextImpl.java:186)
at org.apache.hadoop.mapred.MapTask.runNewMapper(MapTask.java:745)
at org.apache.hadoop.mapred.MapTask.run(MapTask.java:341)
at org.apache.hadoop.mapred.YarnChild$2.run(YarnChild.java:170)
at java.security.AccessController.doPrivileged(Native Method)
at javax.security.auth.Subject.doAs(Subject.java:422)
at org.apache.hadoop.security.UserGroupInformation.doAs(UserGroupInformation.java:1866)
at org.apache.hadoop.mapred.YarnChild.main(YarnChild.java:164)
Caused by: java.lang.ClassNotFoundException: Class water.hadoop.h2omapper not found
at org.apache.hadoop.conf.Configuration.getClassByName(Configuration.java:2147)
at org.apache.hadoop.conf.Configuration.getClass(Configuration.java:2239)
... 8 more
2017-10-13 07:49:24,506 INFO [IPC Server handler 1 on 40503] org.apache.hadoop.mapred.TaskAttemptListenerImpl: Diagnostics report from attempt_1507793796947_0002_m_000002_0: Error: java.lang.RuntimeException: java.lang.ClassNotFoundException: Class water.hadoop.h2omapper not found
at org.apache.hadoop.conf.Configuration.getClass(Configuration.java:2241)
at org.apache.hadoop.mapreduce.task.JobContextImpl.getMapperClass(JobContextImpl.java:186)
at org.apache.hadoop.mapred.MapTask.runNewMapper(MapTask.java:745)
at org.apache.hadoop.mapred.MapTask.run(MapTask.java:341)
at org.apache.hadoop.mapred.YarnChild$2.run(YarnChild.java:170)
at java.security.AccessController.doPrivileged(Native Method)
at javax.security.auth.Subject.doAs(Subject.java:422)
at org.apache.hadoop.security.UserGroupInformation.doAs(UserGroupInformation.java:1866)
at org.apache.hadoop.mapred.YarnChild.main(YarnChild.java:164)
Caused by: java.lang.ClassNotFoundException: Class water.hadoop.h2omapper not found
at org.apache.hadoop.conf.Configuration.getClassByName(Configuration.java:2147)
at org.apache.hadoop.conf.Configuration.getClass(Configuration.java:2239)
... 8 more
2017-10-13 07:49:24,507 INFO [AsyncDispatcher event handler] org.apache.hadoop.mapreduce.v2.app.job.impl.TaskAttemptImpl: Diagnostics report from attempt_1507793796947_0002_m_000002_0: Error: java.lang.RuntimeException: java.lang.ClassNotFoundException: Class water.hadoop.h2omapper not found
at org.apache.hadoop.conf.Configuration.getClass(Configuration.java:2241)
at org.apache.hadoop.mapreduce.task.JobContextImpl.getMapperClass(JobContextImpl.java:186)
at org.apache.hadoop.mapred.MapTask.runNewMapper(MapTask.java:745)
at org.apache.hadoop.mapred.MapTask.run(MapTask.java:341)
at org.apache.hadoop.mapred.YarnChild$2.run(YarnChild.java:170)
at java.security.AccessController.doPrivileged(Native Method)
at javax.security.auth.Subject.doAs(Subject.java:422)
at org.apache.hadoop.security.UserGroupInformation.doAs(UserGroupInformation.java:1866)
at org.apache.hadoop.mapred.YarnChild.main(YarnChild.java:164)
Caused by: java.lang.ClassNotFoundException: Class water.hadoop.h2omapper not found
at org.apache.hadoop.conf.Configuration.getClassByName(Configuration.java:2147)
at org.apache.hadoop.conf.Configuration.getClass(Configuration.java:2239)
... 8 more
此处提供完整日志。
如有任何帮助，我们将不胜感激。
谨致问候，Markus
您是否能够运行其他YARN作业？(就像π的例子一样。)
应用程序id显示您的Hadoop集群于2017年10月12日星期四07:36:36 UTC(即昨天)启动，这是该集群尝试运行的第一个(也是第二个)作业。
此外，集群中节点的大小非常小。
在我看来，所有这些都像是你试图成为自己的Hadoop管理员，但还没有成功。：)
继续尝试，当集群配置正确时，H2O就会运行。
根据您提供的部分日志，以下行有助于理解一点：
2017-10-12 07:45:02,172 FATAL [IPC Server handler 1 on 39365]
org.apache.hadoop.mapred.TaskAttemptListenerImpl: Task:
attempt_1507726330188_0001_m_000002_0 - exited :
java.lang.RuntimeException: java.lang.ClassNotFoundException: Class water.hadoop.h2omapper not found
很明显，任务id#2实例#0(或第一个实例)由于缺少类而失败。因此，如果任务#2显示错误，则意味着另一个任务#1已经在运行。这也意味着作业已启动或处于运行状态。因此，问题发生在作业执行阶段。这意味着执行该特定任务的DataNode无法找到H2O驱动程序库。因此，节点或节点上的文件系统可能由于某种原因而不可用。如果你研究一下你的详细日志，你就会明白为什么会发生这种情况。
【其他详细信息】
由于权限或文件系统问题，任何映射程序都无法访问h20driver.jar，这就是您的作业未启动的原因。您应该确保正确修复Hadoop权限和可访问性，这样您就可以在没有root的情况下启动任何"Hadoop"命令，并且需要超级用户别名。