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Hadoop >> mail # user >> Re: Why my tests shows Yarn is worse than MRv1 for terasort?


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Re: Why my tests shows Yarn is worse than MRv1 for terasort?
I should have brought this up earlier - the Terasort benchmark requirements
changed recently to make data less compressible.  The MR2 version of
Terasort has this change, but the MR1 version does not.    So Snappy should
be working fine, but the data that MR2 is using is less compressible.
On Wed, Oct 23, 2013 at 4:48 PM, Jian Fang <[EMAIL PROTECTED]>wrote:

> Ok, I think I know where the problem is now. I used snappy to compress map
> output.
>
> Calculate the compression ratio = "Map output materialized bytes"/"Map
> output bytes"
>
> MR2
> 440519309909/1020000000000 = 0.431881676
>
> MR1
> 240948272514/1000000000000 = 0.240948273
>
>
> Seems something is wrong with the snappy in my Hadoop 2 and as a result,
> MR2 needs to fetch much more data during shuffle phase. Any way to check
> snappy in MR2?
>
>
>
>
> On Wed, Oct 23, 2013 at 4:26 PM, Jian Fang <[EMAIL PROTECTED]>wrote:
>
>> Looked at the results for MR1 and MR2. Reduce input groups for MR1 is
>> 4,294,967,296, but 10,000,000,000 for MR2.
>> That is to say the number of unique keys fed into the reducers is
>> 10000000000 in MR2, which is really wired. Any problem in the terasort code?
>>
>>
>> On Wed, Oct 23, 2013 at 2:16 PM, Jian Fang <[EMAIL PROTECTED]
>> > wrote:
>>
>>> Reducing the number of map containers to 8 slightly improve the total
>>> time to 84 minutes. Here is output. Also, from the log, there is no clear
>>> reason why the containers are killed other than the message such as
>>> "Container killed by the
>>> ApplicationMaster../container_1382237301855_0001_01_000001/syslog:Container
>>> killed on request. Exit code is 143"
>>>
>>>
>>> 2013-10-23 21:09:34,325 INFO org.apache.hadoop.mapreduce.Job (main):
>>> Counters: 46
>>>         File System Counters
>>>                 FILE: Number of bytes read=455484809066
>>>                 FILE: Number of bytes written=896642344343
>>>
>>>                 FILE: Number of read operations=0
>>>                 FILE: Number of large read operations=0
>>>                 FILE: Number of write operations=0
>>>                 HDFS: Number of bytes read=1000000841624
>>>
>>>                 HDFS: Number of bytes written=1000000000000
>>>                 HDFS: Number of read operations=25531
>>>
>>>                 HDFS: Number of large read operations=0
>>>                 HDFS: Number of write operations=150
>>>
>>>         Job Counters
>>>                 Killed map tasks=1
>>>                 Killed reduce tasks=11
>>>                 Launched map tasks=7449
>>>                 Launched reduce tasks=86
>>>                 Data-local map tasks=7434
>>>                 Rack-local map tasks=15
>>>                 Total time spent by all maps in occupied slots
>>> (ms)=1030941232
>>>                 Total time spent by all reduces in occupied slots
>>> (ms)=1574732272
>>>
>>>         Map-Reduce Framework
>>>                 Map input records=10000000000
>>>                 Map output records=10000000000
>>>                 Map output bytes=1020000000000
>>>                 Map output materialized bytes=440519309909
>>>                 Input split bytes=841624
>>>
>>>                 Combine input records=0
>>>                 Combine output records=0
>>>                 Reduce input groups=10000000000
>>>                 Reduce shuffle bytes=440519309909
>>>
>>>                 Reduce input records=10000000000
>>>                 Reduce output records=10000000000
>>>                 Spilled Records=20000000000
>>>                 Shuffled Maps =558600
>>>                 Failed Shuffles=0
>>>                 Merged Map outputs=558600
>>>                 GC time elapsed (ms)=2855534
>>>                 CPU time spent (ms)=170381420
>>>                 Physical memory (bytes) snapshot=3704938954752
>>>                 Virtual memory (bytes) snapshot=11455208308736
>>>                 Total committed heap usage (bytes)=4523248582656
>>>         Shuffle Errors
>>>                 BAD_ID=0