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From Björn-Elmar Macek <ma...@cs.uni-kassel.de>
Subject Re: Hadoop Debugging in LocalMode (Breakpoints not reached)
Date Fri, 25 May 2012 08:53:27 GMT
Although the reactions did not give me the feeling there was much 
interest in my case, i have found a "solution" and some reasons for my 
problem. You might be interested in the discussion on Stackoverflow:
http://stackoverflow.com/questions/10720132/hadoop-reducer-is-waiting-for-mapper-inputs


Am 23.05.2012 10:47, schrieb Björn-Elmar Macek:
> Ok, i have look at the logs some further and googled every tiny bit of 
> them, hoping to find an answer out there.
> I fear that the following line nails my problem at a big scale:
>
> 12/05/22 01:30:21 INFO mapred.ReduceTask: 
> attempt_local_0001_r_000000_0 Need another 2 map output(s)
> where 0 is already in progress
>
> I found several discussions to problems, that also had this line in 
> their logs. I have checked my code for the following:
>
> * All inputs are collected in the mapper (tho not all would be neccessary)
> * The Comparators run well and return proper values for all inputs
> * The Partitioner always returns proper values
>
> Please, i would really need a hint, to where i have to look.
> Am 22.05.2012 16:57, schrieb Björn-Elmar Macek:
>> Hi Jayaseelan,
>>
>> thanks for the bump! ;)
>>
>> I have continued working on the problem, but with no further success. 
>> I emptied the log directory and started the debugging all over again, 
>> resulting in no new logfiles, so i guess the program did not run into 
>> serious problems. Also all the code other classes, namely ...
>>
>> * Mapper
>> * Partitioner
>> * OutputKeyComparatorClass
>>
>> is executed and can easily be debugged. Stil the Reducer and the 
>> OutputValueGroupingComparator do NOT work. After the execution of the 
>> comparisons made by OutputKeyComparatorClass i get alot of active 
>> processes in my debugging view in eclipse:
>>
>> 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)
>>     Daemon Thread [Thread for merging in memory files] (Running)
>>     Thread [MapOutputCopier attempt_local_0001_r_000000_0.4] (Running)
>>     Thread [MapOutputCopier attempt_local_0001_r_000000_0.3] (Running)
>>     Thread [MapOutputCopier attempt_local_0001_r_000000_0.1] (Running)
>>     Thread [MapOutputCopier attempt_local_0001_r_000000_0.2] (Running)
>>     Daemon Thread [Thread for merging on-disk files] (Running)
>>     Daemon Thread [Thread for polling Map Completion Events] (Running)
>>
>> And those processes are running, but obviously waiting for something, 
>> since no output is produced. And it is not due to the havy load of 
>> input data, since this is a 10 line csv file, which shouldnt make any 
>> problems.
>>
>> I somehow have the feeling that the framework cannot handle my 
>> classes, but i dont understand why.
>>
>> I would really appreciate a decent hint, how to fix that.
>>
>> Thanks you for your time and help!
>> Björn-Elmar
>> Am 22.05.2012 12:38, schrieb Jayaseelan E:
>>>
>>> ------------------------------------------------------------------------
>>> *From:* Björn-Elmar Macek [mailto:macek@cs.uni-kassel.de]
>>> *Sent:* Tuesday, May 22, 2012 3:12 PM
>>> *To:* hdfs-user@hadoop.apache.org
>>> *Subject:* Hadoop Debugging in LocalMode (Breakpoints not reached)
>>>
>>> Hi there,
>>>
>>>
>>> i am currently trying to get rid of bugs in my Hadoop program by 
>>> debugging it. Everything went fine til some point yesterday. I dont 
>>> know what exactly happened, but my program does not stop at 
>>> breakpoints within the Reducer and also not within the RawComparator 
>>> for the values which i do use for sorting my inputs in the 
>>> ReducerIterator.
>>> (see the classes set for the conf below:)
>>>
>>> conf.setOutputValueGroupingComparator(TwitterValueGroupingComparator.class);
>>> conf.setReducerClass(RetweetReducer.class);
>>>
>>> The log looks like this:
>>>
>>> Warning: $HADOOP_HOME is deprecated.
>>>
>>> Listening for transport dt_socket at address: 5002
>>>
>>> 12/05/21 19:24:20 INFO util.NativeCodeLoader: Loaded the 
>>> native-hadoop library
>>>
>>> 12/05/21 19:24:20 WARN mapred.JobClient: Use GenericOptionsParser 
>>> for parsing the arguments. Applications should implement Tool for 
>>> the same.
>>>
>>> 12/05/21 19:24:20 WARN snappy.LoadSnappy: Snappy native library not 
>>> loaded
>>>
>>> 12/05/21 19:24:20 INFO mapred.FileInputFormat: Total input paths to 
>>> process : 2
>>>
>>> 12/05/21 19:24:20 WARN conf.Configuration: 
>>> file:/tmp/hadoop-ema/mapred/local/localRunner/job_local_0001.xml:a 
>>> attempt to override final parameter: fs.default.name;Ignoring.
>>>
>>> 12/05/21 19:24:20 WARN conf.Configuration: 
>>> file:/tmp/hadoop-ema/mapred/local/localRunner/job_local_0001.xml:a 
>>> attempt to override final parameter: mapred.job.tracker;Ignoring.
>>>
>>> 12/05/21 19:24:20 INFO mapred.JobClient: Running job: job_local_0001
>>>
>>> 12/05/21 19:24:20 INFO util.ProcessTree: setsid exited with exit code 0
>>>
>>> 12/05/21 19:24:21 INFO mapred.Task:Using ResourceCalculatorPlugin : 
>>> org.apache.hadoop.util.LinuxResourceCalculatorPlugin@1c4ff2c
>>>
>>> 12/05/21 19:24:21 INFO mapred.MapTask: numReduceTasks: 1
>>>
>>> 12/05/21 19:24:21 INFO mapred.MapTask: io.sort.mb = 100
>>>
>>> 12/05/21 19:24:22 INFO mapred.JobClient:map 0% reduce 0%
>>>
>>> 12/05/21 19:24:22 INFO mapred.MapTask: data buffer = 79691776/99614720
>>>
>>> 12/05/21 19:24:22 INFO mapred.MapTask: record buffer = 262144/327680
>>>
>>> 12/05/21 19:24:22 INFO mapred.MapTask: Starting flush of map output
>>>
>>> 12/05/21 19:24:22 INFO mapred.MapTask: Finished spill 0
>>>
>>> 12/05/21 19:24:22 INFO mapred.Task: 
>>> Task:attempt_local_0001_m_000000_0 is done. And is in the process of 
>>> commiting
>>>
>>> 12/05/21 19:24:23 INFO mapred.LocalJobRunner: 
>>> file:/home/ema/INPUT-H/tweets_ext:0+968
>>>
>>> 12/05/21 19:24:23 INFO mapred.Task: Task 
>>> 'attempt_local_0001_m_000000_0' done.
>>>
>>> 12/05/21 19:24:23 INFO mapred.Task:Using ResourceCalculatorPlugin : 
>>> org.apache.hadoop.util.LinuxResourceCalculatorPlugin@1e8c585
>>>
>>> 12/05/21 19:24:23 INFO mapred.MapTask: numReduceTasks: 1
>>>
>>> 12/05/21 19:24:23 INFO mapred.MapTask: io.sort.mb = 100
>>>
>>> 12/05/21 19:24:24 INFO mapred.MapTask: data buffer = 79691776/99614720
>>>
>>> 12/05/21 19:24:24 INFO mapred.MapTask: record buffer = 262144/327680
>>>
>>> 12/05/21 19:24:24 INFO mapred.MapTask: Starting flush of map output
>>>
>>> 12/05/21 19:24:24 INFO mapred.Task: 
>>> Task:attempt_local_0001_m_000001_0 is done. And is in the process of 
>>> commiting
>>>
>>> 12/05/21 19:24:24 INFO mapred.JobClient:map 100% reduce 0%
>>>
>>> 12/05/21 19:24:26 INFO mapred.LocalJobRunner: 
>>> file:/home/ema/INPUT-H/tweets~:0+0
>>>
>>> 12/05/21 19:24:26 INFO mapred.Task: Task 
>>> 'attempt_local_0001_m_000001_0' done.
>>>
>>> 12/05/21 19:24:26 INFO mapred.Task:Using ResourceCalculatorPlugin : 
>>> org.apache.hadoop.util.LinuxResourceCalculatorPlugin@191e4c
>>>
>>> 12/05/21 19:24:26 INFO mapred.ReduceTask: ShuffleRamManager: 
>>> MemoryLimit=709551680, MaxSingleShuffleLimit=177387920
>>>
>>> 12/05/21 19:24:27 INFO mapred.ReduceTask: 
>>> attempt_local_0001_r_000000_0 Need another 2 map output(s) where 0 
>>> is already in progress
>>>
>>> 12/05/21 19:24:27 INFO mapred.ReduceTask: 
>>> attempt_local_0001_r_000000_0 Thread started: Thread for merging 
>>> on-disk files
>>>
>>> 12/05/21 19:24:27 INFO mapred.ReduceTask: 
>>> attempt_local_0001_r_000000_0 Thread waiting: Thread for merging 
>>> on-disk files
>>>
>>> 12/05/21 19:24:27 INFO mapred.ReduceTask: 
>>> attempt_local_0001_r_000000_0 Scheduled 0 outputs (0 slow hosts and0 
>>> dup hosts)
>>>
>>> 12/05/21 19:24:27 INFO mapred.ReduceTask: 
>>> attempt_local_0001_r_000000_0 Thread started: Thread for merging in 
>>> memory files
>>>
>>> 12/05/21 19:24:27 INFO mapred.ReduceTask: 
>>> attempt_local_0001_r_000000_0 Thread started: Thread for polling Map 
>>> Completion Events
>>>
>>> 12/05/21 19:24:32 INFO mapred.LocalJobRunner: reduce > copy >
>>>
>>> 12/05/21 19:24:35 INFO mapred.LocalJobRunner: reduce > copy >
>>>
>>> 12/05/21 19:24:42 INFO mapred.LocalJobRunner: reduce > copy >
>>>
>>> 12/05/21 19:24:48 INFO mapred.LocalJobRunner: reduce > copy >
>>>
>>> 12/05/21 19:24:51 INFO mapred.LocalJobRunner: reduce > copy >
>>>
>>> 12/05/21 19:24:57 INFO mapred.LocalJobRunner: reduce > copy >
>>>
>>> ... etc ...
>>>
>>> Is there something i have missed?
>>>
>>> Thanks for your help in advance!
>>>
>>> Best regards,
>>> Björn-Elmar
>>>
>>>
>>
>


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