Question

我使用新的2.x版本设置了Hadoop集群。我根据this guide安装了snappy和hadoop snappy，以便在地图输出中启用snappy压缩。

运行示例wordcount时，发生错误：

[dm@node1 ~]$ hadoop jar /opt/hadoop-2.0.5-alpha/share/hadoop/mapreduce/hadoop-mapreduce-examples-2.0.5-alpha.jar wordcount /in /out
13/09/06 05:09:52 WARN util.NativeCodeLoader: Unable to load native-hadoop library for your platform... using builtin-java classes where applicable
13/09/06 05:09:53 INFO service.AbstractService: Service:org.apache.hadoop.yarn.client.YarnClientImpl is inited.
13/09/06 05:09:53 INFO service.AbstractService: Service:org.apache.hadoop.yarn.client.YarnClientImpl is started.
13/09/06 05:10:04 INFO input.FileInputFormat: Total input paths to process : 1
13/09/06 05:10:04 INFO snappy.LoadSnappy: Snappy native library loaded
13/09/06 05:10:04 INFO lzo.GPLNativeCodeLoader: Loaded native gpl library
13/09/06 05:10:04 INFO lzo.LzoCodec: Successfully loaded & initialized native-lzo library [hadoop-lzo rev d0f5a10f99f1b2af4f6610447052c5a67b8b1cc7]
13/09/06 05:10:04 INFO mapreduce.JobSubmitter: number of splits:1
13/09/06 05:10:04 WARN conf.Configuration: mapred.jar is deprecated. Instead, use mapreduce.job.jar
13/09/06 05:10:04 WARN conf.Configuration: mapred.output.value.class is deprecated. Instead, use mapreduce.job.output.value.class
13/09/06 05:10:04 WARN conf.Configuration: mapreduce.combine.class is deprecated. Instead, use mapreduce.job.combine.class
13/09/06 05:10:04 WARN conf.Configuration: mapreduce.map.class is deprecated. Instead, use mapreduce.job.map.class
13/09/06 05:10:04 WARN conf.Configuration: mapred.job.name is deprecated. Instead, use mapreduce.job.name
13/09/06 05:10:04 WARN conf.Configuration: mapreduce.reduce.class is deprecated. Instead, use mapreduce.job.reduce.class
13/09/06 05:10:04 WARN conf.Configuration: mapred.input.dir is deprecated. Instead, use mapreduce.input.fileinputformat.inputdir
13/09/06 05:10:04 WARN conf.Configuration: mapred.output.dir is deprecated. Instead, use mapreduce.output.fileoutputformat.outputdir
13/09/06 05:10:04 WARN conf.Configuration: mapred.map.tasks is deprecated. Instead, use mapreduce.job.maps
13/09/06 05:10:04 WARN conf.Configuration: mapred.output.key.class is deprecated. Instead, use mapreduce.job.output.key.class
13/09/06 05:10:04 WARN conf.Configuration: mapred.working.dir is deprecated. Instead, use mapreduce.job.working.dir
13/09/06 05:10:05 INFO mapreduce.JobSubmitter: Submitting tokens for job: job_1378415309099_0001
13/09/06 05:10:06 INFO client.YarnClientImpl: Submitted application application_1378415309099_0001 to ResourceManager at node1/192.168.56.101:60832
13/09/06 05:10:06 INFO mapreduce.Job: The url to track the job: http://node1:60888/proxy/application_1378415309099_0001/
13/09/06 05:10:06 INFO mapreduce.Job: Running job: job_1378415309099_0001
13/09/06 05:10:32 INFO mapreduce.Job: Job job_1378415309099_0001 running in uber mode : false
13/09/06 05:10:32 INFO mapreduce.Job:  map 0% reduce 0%
13/09/06 05:10:53 INFO mapreduce.Job:  map 100% reduce 0%
13/09/06 05:11:02 INFO mapreduce.Job: Task Id : attempt_1378415309099_0001_m_000000_0, Status : FAILED
Error: org.apache.hadoop.util.NativeCodeLoader.buildSupportsSnappy()Z
Container killed by the ApplicationMaster.


13/09/06 05:11:03 INFO mapreduce.Job:  map 0% reduce 0%
13/09/06 05:11:07 INFO mapreduce.Job: Task Id : attempt_1378415309099_0001_m_000000_1, Status : FAILED
Error: org.apache.hadoop.util.NativeCodeLoader.buildSupportsSnappy()Z
13/09/06 05:11:13 INFO mapreduce.Job: Task Id : attempt_1378415309099_0001_m_000000_2, Status : FAILED
Error: org.apache.hadoop.util.NativeCodeLoader.buildSupportsSnappy()Z
13/09/06 05:11:19 INFO mapreduce.Job:  map 100% reduce 0%
13/09/06 05:11:19 INFO mapreduce.Job: Job job_1378415309099_0001 failed with state FAILED due to: Task failed task_1378415309099_0001_m_000000
Job failed as tasks failed. failedMaps:1 failedReduces:0

13/09/06 05:11:19 INFO mapreduce.Job: Counters: 6
    Job Counters 
        Failed map tasks=4
        Launched map tasks=4
        Other local map tasks=3
        Data-local map tasks=1
        Total time spent by all maps in occupied slots (ms)=42989
        Total time spent by all reduces in occupied slots (ms)=0

我搜索了谷歌有关错误消息“错误：org.apache.hadoop.util.NativeCodeLoader.buildSupportsSnappy（）Z”，还没有找到解决此问题的方法。所以我想知道如何在Hadoop 2.x中启用snappy压缩？感谢。

Answer 1

好的服务器：

<script>
    alert('hi Marky!');
</script>

不好的服务器：

$ hadoop checknative -a | grep snappy
15/06/18 14:51:05 INFO bzip2.Bzip2Factory: Successfully loaded & initialized native-bzip2 library system-native
15/06/18 14:51:05 INFO zlib.ZlibFactory: Successfully loaded & initialized native-zlib library
snappy:  true /opt/cloudera/parcels/CDH-5.4.2-1.cdh5.4.2.p0.2/lib/hadoop/lib/native/libsnappy.so.1

注意在一个案例中，“hadoop checknative”命令返回系统的libsnappy，在另一种情况下 - 一个来自Hadoop distrubution。如果您在某些主机上有hadoop报告他们使用系统的libsnappy，则会出现错误，例如“.hadoop.mapred.YarnChild：Error child child：java.lang.UnsatisfiedLinkError：org.apache.hadoop.util.NativeCodeLoader.buildSupportsSnappy（）Z at org.apache.hadoop.util.NativeCodeLoader.buildSupportsSnappy（Native Method） “很有可能。

Answer 2

从您提供的输出（WARN util.NativeCodeLoader: Unable to load native-hadoop library for your platform...等...）看起来您的本机库未加载。我认为值得尝试build and install本地库，然后在<HADOOP_HOME>/lib/native/内添加Snappy库。我认为这可能会解决问题。希望有所帮助！

Answer 3

看起来您的代码无法加载snappy本机库。对此可能有两种可能的解释。您使用的snappy版本与您安装的hadoop版本不兼容。或者您尚未在类路径中添加库。

Answer 4

该指南的第二个参数是错误的。

改为使用 mapreduce.map.output.compress.codec 。

Hadoop 2.x中的Snappy压缩错误

4 个答案: