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Posted to mapreduce-user@hadoop.apache.org by Mat Kelcey <ma...@gmail.com> on 2011/12/03 23:35:41 UTC

determining what files made up a failing task

Hi folks,

I have a Hadoop 0.20.2 map only job with thousands of inputs tasks;
I'm using the org.apache.nutch.tools.arc.ArcInputFormat input format
so each task corresponds to a single file in HDFS

Most of the way into the job it hits a task that causes the input
format to OOM. After 4 attempts it fails the job.
Now this is obviously not great but for the purpose of my job I'd be
happy to just throw this input file away, it's only one of thousands
and I don't need exact results.

The trouble is I can't work out where what file this task corresponds to?

The closest I can find is that the job history file lists a STATE_STRING
( eg STATE_STRING="hdfs://ip-10-115-29-44\.ec2\.internal:9000/user/hadoop/arc_files\.aa/2009/09/17/0/1253240925734_0\.arc\.gz:0+100425468"
)

but this is _only_ for the successfully completed ones, for the failed
one I'm actually interested in there is nothing
MapAttempt TASK_TYPE="MAP" TASKID="task_201112030459_0011_m_004130"
TASK_ATTEMPT_ID="attempt_201112030459_0011_m_004130_0"
TASK_STATUS="FAILED" FINISH_TIME="1322901661261"
HOSTNAME="ip-10-218-57-227\.ec2\.internal" ERROR="Error: null" .

I grepped through all the hadoop logs and couldn't find anything that
relates this task to the files in it's split
Any ideas where this info might be recorded?

Cheers,
Mat

Re: determining what files made up a failing task

Posted by Praveen Sripati <pr...@gmail.com>.
Matt,

I could not find the properties in the documentation, so I mentioned this
feature as hidden. As Harsh mentioned there is an API.

There was a blog entry on '
Automatically Documenting Apache Hadoop Configuration' from Cloudera. It
would be great if it is contributed to Apache and made part of the build
process. I suggested it before, but there was no response.

http://www.cloudera.com/blog/2011/08/automatically-documenting-apache-hadoop-configuration/

Regards,
Praveen

On Sun, Dec 4, 2011 at 9:07 PM, Harsh J <ha...@cloudera.com> wrote:

> Mat,
>
> Perhaps you can simply set a percentage of failure toleration for your job.
>
> Doable via
> http://hadoop.apache.org/common/docs/r0.20.2/api/org/apache/hadoop/mapred/JobConf.html#setMaxMapTaskFailuresPercent(int)
>  and
> http://hadoop.apache.org/common/docs/r0.20.2/api/org/apache/hadoop/mapred/JobConf.html#setMaxReduceTaskFailuresPercent(int)
>
> If you set it to 10%, your job still passes if 10% of total Map or Reduce
> tasks failed. I think this fits your use-case.
>
> On 04-Dec-2011, at 4:05 AM, Mat Kelcey wrote:
>
> Hi folks,
>
> I have a Hadoop 0.20.2 map only job with thousands of inputs tasks;
> I'm using the org.apache.nutch.tools.arc.ArcInputFormat input format
> so each task corresponds to a single file in HDFS
>
> Most of the way into the job it hits a task that causes the input
> format to OOM. After 4 attempts it fails the job.
> Now this is obviously not great but for the purpose of my job I'd be
> happy to just throw this input file away, it's only one of thousands
> and I don't need exact results.
>
> The trouble is I can't work out where what file this task corresponds to?
>
> The closest I can find is that the job history file lists a STATE_STRING
> ( eg STATE_STRING="
> hdfs://ip-10-115-29-44\.ec2\.internal:9000/user/hadoop/arc_files\.aa/2009/09/17/0/1253240925734_0\.arc\.gz:0+100425468
> "
> )
>
> but this is _only_ for the successfully completed ones, for the failed
> one I'm actually interested in there is nothing
> MapAttempt TASK_TYPE="MAP" TASKID="task_201112030459_0011_m_004130"
> TASK_ATTEMPT_ID="attempt_201112030459_0011_m_004130_0"
> TASK_STATUS="FAILED" FINISH_TIME="1322901661261"
> HOSTNAME="ip-10-218-57-227\.ec2\.internal" ERROR="Error: null" .
>
> I grepped through all the hadoop logs and couldn't find anything that
> relates this task to the files in it's split
> Any ideas where this info might be recorded?
>
> Cheers,
> Mat
>
>
>

Re: determining what files made up a failing task

Posted by Harsh J <ha...@cloudera.com>.
Mat,

Perhaps you can simply set a percentage of failure toleration for your job.

Doable via http://hadoop.apache.org/common/docs/r0.20.2/api/org/apache/hadoop/mapred/JobConf.html#setMaxMapTaskFailuresPercent(int) and http://hadoop.apache.org/common/docs/r0.20.2/api/org/apache/hadoop/mapred/JobConf.html#setMaxReduceTaskFailuresPercent(int)

If you set it to 10%, your job still passes if 10% of total Map or Reduce tasks failed. I think this fits your use-case.

On 04-Dec-2011, at 4:05 AM, Mat Kelcey wrote:

> Hi folks,
> 
> I have a Hadoop 0.20.2 map only job with thousands of inputs tasks;
> I'm using the org.apache.nutch.tools.arc.ArcInputFormat input format
> so each task corresponds to a single file in HDFS
> 
> Most of the way into the job it hits a task that causes the input
> format to OOM. After 4 attempts it fails the job.
> Now this is obviously not great but for the purpose of my job I'd be
> happy to just throw this input file away, it's only one of thousands
> and I don't need exact results.
> 
> The trouble is I can't work out where what file this task corresponds to?
> 
> The closest I can find is that the job history file lists a STATE_STRING
> ( eg STATE_STRING="hdfs://ip-10-115-29-44\.ec2\.internal:9000/user/hadoop/arc_files\.aa/2009/09/17/0/1253240925734_0\.arc\.gz:0+100425468"
> )
> 
> but this is _only_ for the successfully completed ones, for the failed
> one I'm actually interested in there is nothing
> MapAttempt TASK_TYPE="MAP" TASKID="task_201112030459_0011_m_004130"
> TASK_ATTEMPT_ID="attempt_201112030459_0011_m_004130_0"
> TASK_STATUS="FAILED" FINISH_TIME="1322901661261"
> HOSTNAME="ip-10-218-57-227\.ec2\.internal" ERROR="Error: null" .
> 
> I grepped through all the hadoop logs and couldn't find anything that
> relates this task to the files in it's split
> Any ideas where this info might be recorded?
> 
> Cheers,
> Mat

Re: determining what files made up a failing task

Posted by Mat Kelcey <ma...@gmail.com>.
> Set the 'mapreduce.map.failures.maxpercent` and
> 'mapreduce.reduce.failures.maxpercent' to the failure tolerance for the job
> to complete irrespective of some task failures.

Thanks!
I crawled the javadoc looking for something like this, I wonder why it's hidden?
Mat

Re: determining what files made up a failing task

Posted by Praveen Sripati <pr...@gmail.com>.
Mat,

There is no need to know the input data which caused the task and finally
the job to fail.

Set the 'mapreduce.map.failures.maxpercent` and
'mapreduce.reduce.failures.maxpercent' to the failure tolerance for the job
to complete irrespective of some task failures.

Again, this is one of the hidden features of Hadoop. Though it was
intyroduced back in 2007 (HADOOP-1144).

If you would like to really nail the problem, then you could use the
IsolationRunner. Here is more information on it.

http://hadoop.apache.org/common/docs/r0.20.205.0/mapred_tutorial.html#IsolationRunner

Regards,
Praveen

On Sun, Dec 4, 2011 at 2:42 PM, Bejoy Ks <be...@gmail.com> wrote:

> Hi Mat
>         I'm not sure of an implicit mechanism in hadoop that logs the
> input splits(file names) each mapper is processing. To analyze that you may
> have to do some custom logging. Just log the input file name on the start
> of map method. The full file path in hdfs can be obtained from the input
> Split as follows
>
> //get the file split being processed
> FileSplit filsp = (FileSplit)context.getInputSplit();
> //get the full path of the file being processed
> log.debug(filsp.getPath());
>
> This works with new map reduce API. In old map reduce API you can get the
> information from JobConf job as
> job.get("map.input.file");
> This line of code you can include in your configure method in case of old
> API.
>
> Hope it helps!...
>
> Regards
> Bejoy.K.S
>
>
> On Sun, Dec 4, 2011 at 4:05 AM, Mat Kelcey <ma...@gmail.com>wrote:
>
>> Hi folks,
>>
>> I have a Hadoop 0.20.2 map only job with thousands of inputs tasks;
>> I'm using the org.apache.nutch.tools.arc.ArcInputFormat input format
>> so each task corresponds to a single file in HDFS
>>
>> Most of the way into the job it hits a task that causes the input
>> format to OOM. After 4 attempts it fails the job.
>> Now this is obviously not great but for the purpose of my job I'd be
>> happy to just throw this input file away, it's only one of thousands
>> and I don't need exact results.
>>
>> The trouble is I can't work out where what file this task corresponds to?
>>
>> The closest I can find is that the job history file lists a STATE_STRING
>> ( eg
>> STATE_STRING="hdfs://ip-10-115-29-44\.ec2\.internal:9000/user/hadoop/arc_files\.aa/2009/09/17/0/1253240925734_0\.arc\.gz:0+100425468"
>> )
>>
>> but this is _only_ for the successfully completed ones, for the failed
>> one I'm actually interested in there is nothing
>> MapAttempt TASK_TYPE="MAP" TASKID="task_201112030459_0011_m_004130"
>> TASK_ATTEMPT_ID="attempt_201112030459_0011_m_004130_0"
>> TASK_STATUS="FAILED" FINISH_TIME="1322901661261"
>> HOSTNAME="ip-10-218-57-227\.ec2\.internal" ERROR="Error: null" .
>>
>> I grepped through all the hadoop logs and couldn't find anything that
>> relates this task to the files in it's split
>> Any ideas where this info might be recorded?
>>
>> Cheers,
>> Mat
>>
>
>

Re: determining what files made up a failing task

Posted by Mat Kelcey <ma...@gmail.com>.
Good idea, I guess I'll just have to run it up again though.
Thanks

On 4 December 2011 01:12, Bejoy Ks <be...@gmail.com> wrote:
> Hi Mat
>         I'm not sure of an implicit mechanism in hadoop that logs the input
> splits(file names) each mapper is processing. To analyze that you may have
> to do some custom logging. Just log the input file name on the start of map
> method. The full file path in hdfs can be obtained from the input Split as
> follows
>
> //get the file split being processed
> FileSplit filsp = (FileSplit)context.getInputSplit();
> //get the full path of the file being processed
> log.debug(filsp.getPath());
>
> This works with new map reduce API. In old map reduce API you can get the
> information from JobConf job as
> job.get("map.input.file");
> This line of code you can include in your configure method in case of old
> API.
>
> Hope it helps!...
>
> Regards
> Bejoy.K.S
>
>
> On Sun, Dec 4, 2011 at 4:05 AM, Mat Kelcey <ma...@gmail.com> wrote:
>>
>> Hi folks,
>>
>> I have a Hadoop 0.20.2 map only job with thousands of inputs tasks;
>> I'm using the org.apache.nutch.tools.arc.ArcInputFormat input format
>> so each task corresponds to a single file in HDFS
>>
>> Most of the way into the job it hits a task that causes the input
>> format to OOM. After 4 attempts it fails the job.
>> Now this is obviously not great but for the purpose of my job I'd be
>> happy to just throw this input file away, it's only one of thousands
>> and I don't need exact results.
>>
>> The trouble is I can't work out where what file this task corresponds to?
>>
>> The closest I can find is that the job history file lists a STATE_STRING
>> ( eg
>> STATE_STRING="hdfs://ip-10-115-29-44\.ec2\.internal:9000/user/hadoop/arc_files\.aa/2009/09/17/0/1253240925734_0\.arc\.gz:0+100425468"
>> )
>>
>> but this is _only_ for the successfully completed ones, for the failed
>> one I'm actually interested in there is nothing
>> MapAttempt TASK_TYPE="MAP" TASKID="task_201112030459_0011_m_004130"
>> TASK_ATTEMPT_ID="attempt_201112030459_0011_m_004130_0"
>> TASK_STATUS="FAILED" FINISH_TIME="1322901661261"
>> HOSTNAME="ip-10-218-57-227\.ec2\.internal" ERROR="Error: null" .
>>
>> I grepped through all the hadoop logs and couldn't find anything that
>> relates this task to the files in it's split
>> Any ideas where this info might be recorded?
>>
>> Cheers,
>> Mat
>
>

Re: determining what files made up a failing task

Posted by Bejoy Ks <be...@gmail.com>.
Hi Mat
        I'm not sure of an implicit mechanism in hadoop that logs the input
splits(file names) each mapper is processing. To analyze that you may have
to do some custom logging. Just log the input file name on the start of map
method. The full file path in hdfs can be obtained from the input Split as
follows

//get the file split being processed
FileSplit filsp = (FileSplit)context.getInputSplit();
//get the full path of the file being processed
log.debug(filsp.getPath());

This works with new map reduce API. In old map reduce API you can get the
information from JobConf job as
job.get("map.input.file");
This line of code you can include in your configure method in case of old
API.

Hope it helps!...

Regards
Bejoy.K.S


On Sun, Dec 4, 2011 at 4:05 AM, Mat Kelcey <ma...@gmail.com> wrote:

> Hi folks,
>
> I have a Hadoop 0.20.2 map only job with thousands of inputs tasks;
> I'm using the org.apache.nutch.tools.arc.ArcInputFormat input format
> so each task corresponds to a single file in HDFS
>
> Most of the way into the job it hits a task that causes the input
> format to OOM. After 4 attempts it fails the job.
> Now this is obviously not great but for the purpose of my job I'd be
> happy to just throw this input file away, it's only one of thousands
> and I don't need exact results.
>
> The trouble is I can't work out where what file this task corresponds to?
>
> The closest I can find is that the job history file lists a STATE_STRING
> ( eg
> STATE_STRING="hdfs://ip-10-115-29-44\.ec2\.internal:9000/user/hadoop/arc_files\.aa/2009/09/17/0/1253240925734_0\.arc\.gz:0+100425468"
> )
>
> but this is _only_ for the successfully completed ones, for the failed
> one I'm actually interested in there is nothing
> MapAttempt TASK_TYPE="MAP" TASKID="task_201112030459_0011_m_004130"
> TASK_ATTEMPT_ID="attempt_201112030459_0011_m_004130_0"
> TASK_STATUS="FAILED" FINISH_TIME="1322901661261"
> HOSTNAME="ip-10-218-57-227\.ec2\.internal" ERROR="Error: null" .
>
> I grepped through all the hadoop logs and couldn't find anything that
> relates this task to the files in it's split
> Any ideas where this info might be recorded?
>
> Cheers,
> Mat
>