Hadoop - Reducer正在等待Mapper输入？

时间：2012-05-23 12:42:01

标签： hadoop local reduce

如标题中所述，当我执行我的Hadoop程序（并在本地模式下调试）时，会发生以下情况：

的 1。我的测试数据中的所有10个csv行都在Mapper，Partitioner和在map-step之后调用的RawComperator（OutputKeyComparatorClass）中正确处理。但是之后不会执行OutputValueGroupingComparatorClass和ReduceClass的函数。

的 2。我的应用程序如下所示。 （由于空间限制，我省略了我用作配置参数的类的实现，直到有人有想法，涉及到它们）： 

public class RetweetApplication {

    public static int DEBUG = 1;
    static String INPUT = "/home/ema/INPUT-H";
    static String OUTPUT = "/home/ema/OUTPUT-H "+ (new Date()).toString();

    public static void main(String[] args) {
    JobClient client = new JobClient();
    JobConf conf = new JobConf(RetweetApplication.class);


    if(DEBUG > 0){
        conf.set("mapred.job.tracker", "local");
        conf.set("fs.default.name", "file:///");
        conf.set("dfs.replication", "1");
    }


    FileInputFormat.setInputPaths(conf, new Path(INPUT));   
    FileOutputFormat.setOutputPath(conf, new Path(OUTPUT));


    //conf.setOutputKeyClass(Text.class);
    //conf.setOutputValueClass(Text.class);
    conf.setMapOutputKeyClass(Text.class);
    conf.setMapOutputValueClass(Text.class);

    conf.setMapperClass(RetweetMapper.class);
    conf.setPartitionerClass(TweetPartitioner.class);
    conf.setOutputKeyComparatorClass(TwitterValueGroupingComparator.class);
    conf.setOutputValueGroupingComparator(TwitterKeyGroupingComparator.class);
    conf.setReducerClass(RetweetReducer.class);

    conf.setOutputFormat(TextOutputFormat.class);

    client.setConf(conf);
    try {
        JobClient.runJob(conf);
    } catch (Exception e) {
        e.printStackTrace();
    }
    }
}

第3。我得到以下控制台输出（抱歉格式，但不知何故，这个日志没有正确格式化）：

  

12/05/22 03:51:05 INFO mapred.MapTask：io.sort.mb = 100 12/05/22   03:51:05 INFO mapred.MapTask：data buffer = 79691776/99614720

     

12/05/22 03:51:05 INFO mapred.MapTask：record buffer = 262144/327680

     

12/05/22 03:51:06 INFO mapred.JobClient：map 0％reduce 0％

     

12/05/22 03:51:11 INFO mapred.LocalJobRunner：   file：/ home / ema / INPUT-H / tweets：0 + 967 12/05/22 03:51:12 INFO   mapred.JobClient：map 39％reduce 0％

     

12/05/22 03:51:14 INFO mapred.LocalJobRunner：   file：/ home / ema / INPUT-H / tweets：0 + 967 12/05/22 03:51:15 INFO   mapred.MapTask：启动地图输出的刷新

     

12/05/22 03:51:15 INFO mapred.MapTask：已完成泄漏0

     

12/05/22 03:51:15 INFO mapred.Task：任务：attempt_local_0001_m_000000_0   已经完成了。并且正在提交

     

12/05/22 03:51:15 INFO mapred.JobClient：地图79％减少0％

     

12/05/22 03:51:17 INFO mapred.LocalJobRunner：   file：/ home / ema / INPUT-H / tweets：0 + 967

     

12/05/22 03:51:17 INFO mapred.LocalJobRunner：   file：/ home / ema / INPUT-H / tweets：0 + 967

     

12/05/22 03:51:17 INFO mapred.Task：任务   ＆＃39; attempt_local_0001_m_000000_0＆＃39;完成。

     

12/05/22 03:51:17 INFO mapred.Task：使用ResourceCalculatorPlugin：   org.apache.hadoop.util.LinuxResourceCalculatorPlugin@35eed0

     

12/05/22 03:51:17 INFO mapred.ReduceTask：ShuffleRamManager：   MemoryLimit = 709551680，MaxSingleShuffleLimit = 177387920

     

12/05/22 03:51:17 INFO mapred.ReduceTask：   attempt_local_0001_r_000000_0线程已启动：用于合并的线程   磁盘文件

     

12/05/22 03:51:17 INFO mapred.ReduceTask：   attempt_local_0001_r_000000_0线程等待：用于合并的线程   磁盘文件

     

12/05/22 03:51:17 INFO mapred.ReduceTask：   attempt_local_0001_r_000000_0线程已启动：用于合并的线程   记忆文件

     

12/05/22 03:51:17 INFO mapred.ReduceTask：attempt_local_0001_r_000000_0需要另外1个地图输出，其中0是   已经在进行中12/05/22 03:51:17 INFO mapred.ReduceTask：   attempt_local_0001_r_000000_0预定0输出（0慢主机和0   复制主持人）

     

12/05/22 03:51:17 INFO mapred.ReduceTask：   attempt_local_0001_r_000000_0线程已启动：用于轮询Map的线程   完成活动

     

12/05/22 03:51:18 INFO mapred.JobClient：map 100％reduce 0％12/05/22 03:51:23 INFO mapred.LocalJobRunner：reduce＆gt;复制＆gt;

从这一点开始，粗体标记的线条无休止地重复。

的 4。在映射器看到每个元组后，很多开放进程都处于活动状态： 

RetweetApplication (1) [Remote Java Application]    
    OpenJDK Client VM[localhost:5002]   
        Thread [main] (Running) 
        Thread [Thread-2] (Running) 
        Daemon Thread [communication thread] (Running)  
        Thread [MapOutputCopier attempt_local_0001_r_000000_0.0] (Running)  
        Thread [MapOutputCopier attempt_local_0001_r_000000_0.1] (Running)  
        Thread [MapOutputCopier attempt_local_0001_r_000000_0.2] (Running)  
        Thread [MapOutputCopier attempt_local_0001_r_000000_0.4] (Running)  
        Thread [MapOutputCopier attempt_local_0001_r_000000_0.3] (Running)  
        Daemon Thread [Thread for merging on-disk files] (Running)  
        Daemon Thread [Thread for merging in memory files] (Running)    
        Daemon Thread [Thread for polling Map Completion Events] (Running)

有什么理由，为什么Hadoop期望来自映射器的更多输出（参见日志中的粗体标记行）比输入目录中的更多？如前所述，我调试了所有输入都在mapper / partitioner / etc中正确处理。

更新 在Chris的帮助下（见评论）我发现，我的程序没有像我预期的那样在localMode中启动：isLocal类中的ReduceTask变量设置为false，虽然它应该是true。

对我来说，绝对不清楚为什么会发生这种情况，因为必须设置为启用独立模式的3个选项才是正确的。令人惊讶的是：local设置被忽略，＆＃34;读取正常光盘＆＃34;设置wasnt，这是非常奇怪的imho，因为我认为local模式和file:///协议是耦合的。

在调试ReduceTask期间，我通过在调试视图中评估isLocal将isLocal=true变量设置为true，然后尝试执行程序的其余部分。它没有成功，这是堆栈跟踪：

12/05/22 14:28:28 INFO mapred.LocalJobRunner: 
12/05/22 14:28:28 INFO mapred.Merger: Merging 1 sorted segments
12/05/22 14:28:28 INFO mapred.Merger: Down to the last merge-pass, with 1 segments left of total size: 1956 bytes
12/05/22 14:28:28 INFO mapred.LocalJobRunner: 
12/05/22 14:28:29 WARN conf.Configuration: file:/tmp/hadoop-ema/mapred/local/localRunner/job_local_0001.xml:a attempt to override final parameter: fs.default.name;  Ignoring.
12/05/22 14:28:29 WARN conf.Configuration: file:/tmp/hadoop-ema/mapred/local/localRunner/job_local_0001.xml:a attempt to override final parameter: mapred.job.tracker;  Ignoring.
12/05/22 14:28:30 INFO ipc.Client: Retrying connect to server: master/127.0.0.1:9001. Already tried 0 time(s).
12/05/22 14:28:31 INFO ipc.Client: Retrying connect to server: master/127.0.0.1:9001. Already tried 1 time(s).
12/05/22 14:28:32 INFO ipc.Client: Retrying connect to server: master/127.0.0.1:9001. Already tried 2 time(s).
12/05/22 14:28:33 INFO ipc.Client: Retrying connect to server: master/127.0.0.1:9001. Already tried 3 time(s).
12/05/22 14:28:34 INFO ipc.Client: Retrying connect to server: master/127.0.0.1:9001. Already tried 4 time(s).
12/05/22 14:28:35 INFO ipc.Client: Retrying connect to server: master/127.0.0.1:9001. Already tried 5 time(s).
12/05/22 14:28:36 INFO ipc.Client: Retrying connect to server: master/127.0.0.1:9001. Already tried 6 time(s).
12/05/22 14:28:37 INFO ipc.Client: Retrying connect to server: master/127.0.0.1:9001. Already tried 7 time(s).
12/05/22 14:28:38 INFO ipc.Client: Retrying connect to server: master/127.0.0.1:9001. Already tried 8 time(s).
12/05/22 14:28:39 INFO ipc.Client: Retrying connect to server: master/127.0.0.1:9001. Already tried 9 time(s).
12/05/22 14:28:39 WARN conf.Configuration: file:/tmp/hadoop-ema/mapred/local/localRunner/job_local_0001.xml:a attempt to override final parameter: fs.default.name;  Ignoring.
12/05/22 14:28:39 WARN conf.Configuration: file:/tmp/hadoop-ema/mapred/local/localRunner/job_local_0001.xml:a attempt to override final parameter: mapred.job.tracker;  Ignoring.
12/05/22 14:28:39 WARN mapred.LocalJobRunner: job_local_0001
java.net.ConnectException: Call to master/127.0.0.1:9001 failed on connection exception: java.net.ConnectException: Connection refused
    at org.apache.hadoop.ipc.Client.wrapException(Client.java:1095)
    at org.apache.hadoop.ipc.Client.call(Client.java:1071)
    at org.apache.hadoop.ipc.RPC$Invoker.invoke(RPC.java:225)
    at $Proxy1.getProtocolVersion(Unknown Source)
    at org.apache.hadoop.ipc.RPC.getProxy(RPC.java:396)
    at org.apache.hadoop.ipc.RPC.getProxy(RPC.java:379)
    at org.apache.hadoop.hdfs.DFSClient.createRPCNamenode(DFSClient.java:119)
    at org.apache.hadoop.hdfs.DFSClient.<init>(DFSClient.java:238)
    at org.apache.hadoop.hdfs.DFSClient.<init>(DFSClient.java:203)
    at org.apache.hadoop.hdfs.DistributedFileSystem.initialize(DistributedFileSystem.java:89)
    at org.apache.hadoop.fs.FileSystem.createFileSystem(FileSystem.java:1386)
    at org.apache.hadoop.fs.FileSystem.access$200(FileSystem.java:66)
    at org.apache.hadoop.fs.FileSystem$Cache.get(FileSystem.java:1404)
    at org.apache.hadoop.fs.FileSystem.get(FileSystem.java:254)
    at org.apache.hadoop.fs.FileSystem.get(FileSystem.java:123)
    at org.apache.hadoop.mapred.ReduceTask$OldTrackingRecordWriter.<init>(ReduceTask.java:446)
    at org.apache.hadoop.mapred.ReduceTask.runOldReducer(ReduceTask.java:490)
    at org.apache.hadoop.mapred.ReduceTask.run(ReduceTask.java:420)
    at org.apache.hadoop.mapred.LocalJobRunner$Job.run(LocalJobRunner.java:260)
Caused by: java.net.ConnectException: Connection refused
    at sun.nio.ch.SocketChannelImpl.checkConnect(Native Method)
    at sun.nio.ch.SocketChannelImpl.finishConnect(SocketChannelImpl.java:592)
    at org.apache.hadoop.net.SocketIOWithTimeout.connect(SocketIOWithTimeout.java:206)
    at org.apache.hadoop.net.NetUtils.connect(NetUtils.java:489)
    at org.apache.hadoop.ipc.Client$Connection.setupConnection(Client.java:434)
    at org.apache.hadoop.ipc.Client$Connection.setupIOstreams(Client.java:560)
    at org.apache.hadoop.ipc.Client$Connection.access$2000(Client.java:184)
    at org.apache.hadoop.ipc.Client.getConnection(Client.java:1202)
    at org.apache.hadoop.ipc.Client.call(Client.java:1046)
    ... 17 more
12/05/22 14:28:39 WARN conf.Configuration: file:/tmp/hadoop-ema/mapred/local/localRunner/job_local_0001.xml:a attempt to override final parameter: fs.default.name;  Ignoring.
12/05/22 14:28:39 WARN conf.Configuration: file:/tmp/hadoop-ema/mapred/local/localRunner/job_local_0001.xml:a attempt to override final parameter: mapred.job.tracker;  Ignoring.
12/05/22 14:28:39 INFO mapred.JobClient: Job complete: job_local_0001
12/05/22 14:28:39 INFO mapred.JobClient: Counters: 20
12/05/22 14:28:39 INFO mapred.JobClient:   File Input Format Counters 
12/05/22 14:28:39 INFO mapred.JobClient:     Bytes Read=967
12/05/22 14:28:39 INFO mapred.JobClient:   FileSystemCounters
12/05/22 14:28:39 INFO mapred.JobClient:     FILE_BYTES_READ=14093
12/05/22 14:28:39 INFO mapred.JobClient:     FILE_BYTES_WRITTEN=47859
12/05/22 14:28:39 INFO mapred.JobClient:   Map-Reduce Framework
12/05/22 14:28:39 INFO mapred.JobClient:     Map output materialized bytes=1960
12/05/22 14:28:39 INFO mapred.JobClient:     Map input records=10
12/05/22 14:28:39 INFO mapred.JobClient:     Reduce shuffle bytes=0
12/05/22 14:28:39 INFO mapred.JobClient:     Spilled Records=10
12/05/22 14:28:39 INFO mapred.JobClient:     Map output bytes=1934
12/05/22 14:28:39 INFO mapred.JobClient:     Total committed heap usage (bytes)=115937280
12/05/22 14:28:39 INFO mapred.JobClient:     CPU time spent (ms)=0
12/05/22 14:28:39 INFO mapred.JobClient:     Map input bytes=967
12/05/22 14:28:39 INFO mapred.JobClient:     SPLIT_RAW_BYTES=82
12/05/22 14:28:39 INFO mapred.JobClient:     Combine input records=0
12/05/22 14:28:39 INFO mapred.JobClient:     Reduce input records=0
12/05/22 14:28:39 INFO mapred.JobClient:     Reduce input groups=0
12/05/22 14:28:39 INFO mapred.JobClient:     Combine output records=0
12/05/22 14:28:39 INFO mapred.JobClient:     Physical memory (bytes) snapshot=0
12/05/22 14:28:39 INFO mapred.JobClient:     Reduce output records=0
12/05/22 14:28:39 INFO mapred.JobClient:     Virtual memory (bytes) snapshot=0
12/05/22 14:28:39 INFO mapred.JobClient:     Map output records=10
12/05/22 14:28:39 INFO mapred.JobClient: Job Failed: NA
java.io.IOException: Job failed!
    at org.apache.hadoop.mapred.JobClient.runJob(JobClient.java:1265)
    at uni.kassel.macek.rtprep.RetweetApplication.main(RetweetApplication.java:50)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:616)
    at org.apache.hadoop.util.RunJar.main(RunJar.java:156)

由于这个堆栈跟踪现在告诉我，在执行期间使用了端口9001，我想不知怎的，xml配置文件会覆盖local-java-made设置（我用于测试），这很奇怪，因为我读了在互联网上一遍又一遍，java覆盖xml配置。如果没有人知道如何纠正这个问题，那就试着简单地擦除所有配置xmls。也许这解决了这个问题......

NEW UPDATE

重命名Hadoops conf文件夹解决了等待复印机的问题，程序执行到最后。遗憾的是，虽然HADOOP_OPTS设置正确，但执行程序不再等待我的调试程序。

简历：它只是一个配置问题：XML可能（对于某些配置参数）覆盖JAVA。如果有人知道如何让调试再次运行，那将是完美的，但是现在我很高兴我再也看不到这个堆栈跟踪了！ ;）

谢谢克里斯的时间和精力！

1 个答案:

答案 0 :(得分：2)

很抱歉我之前没有看到这个，但您似乎在conf xml文件中将两个重要的配置属性设置为final，如以下日志语句所示：

12/05/22 14:28:29 WARN conf.Configuration: file:/tmp/hadoop-ema/mapred/local/localRunner/job_local_0001.xml:a attempt to override final parameter: fs.default.name;  Ignoring.
12/05/22 14:28:29 WARN conf.Configuration: file:/tmp/hadoop-ema/mapred/local/localRunner/job_local_0001.xml:a attempt to override final parameter: mapred.job.tracker;  Ignoring.

这意味着您的作业无法实际以本地模式运行，它以本地模式启动，但是reducer读取序列化作业配置并确定它不处于本地模式，并尝试通过任务跟踪器获取地图输出端口。

你说你的修复是重命名conf文件夹 - 这将默认hadoop回到默认配置，其中这两个属性没有标记为'final'

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