Thanks Ted, I agree 2 nodes is an uncommon cluster settings, but it's only for
test and as a benchmark for the future plan. Yes, I'm going to upgrade to
Mahout 0.6, and with luck i have resolve the problem by increase the map/reduce
tasks settings, 2 tasks (the default) for each is a too small setting for my
previous test, it's a dual quad core CPU anyway.
> Subject: Re: Exception during running
> RowSimilarityJob-Mapper-EntriesToVectorsReducer job
> From: [email protected]
> Date: Wed, 19 Oct 2011 07:58:19 -0600
> To: [email protected]
>
> The latest version has many bug fixes. You may be seeing such a bug.
>
> Sent from my iPhone
>
> On Oct 19, 2011, at 2:27, WangRamon <[email protected]> wrote:
>
> >
> > Yes, I'm still using version 0.5, the plan is to verify it can work on 0.5
> > and get some benchmark first then moving forward to 0.6, Sebastian, do you
> > think it's a problem related to Mahout? (Not Hadoop?) And do you think 0.6
> > will bring us a huge performance increase? Thanks. CheersRamon
> >> Date: Wed, 19 Oct 2011 10:20:24 +0200
> >> From: [email protected]
> >> To: [email protected]
> >> Subject: Re: Exception during running
> >> RowSimilarityJob-Mapper-EntriesToVectorsReducer job
> >>
> >> It seems like you're still not using Mahout 0.6. Please use the latest
> >> version and apply appropriate down sampling to your input data. You
> >> should also try to get access to a cluster with more than 2 machines.
> >>
> >> --sebastian
> >>
> >> On 19.10.2011 10:16, WangRamon wrote:
> >>>
> >>>
> >>>
> >>>
> >>> Hi Guys I'm continuing running the test case with a 1GB data file which
> >>> contains 600000 users and 2000000 items, all the jobs are running in a 2
> >>> two nodes cluster, each node has 32GB RAM and 8 core CPU, the
> >>> RecommenderJob running until it reach
> >>> RowSimilarityJob-Mapper-EntriesToVectorsReducer Job, see below for the
> >>> error log: 11/10/18 23:09:34 INFO mapred.JobClient: map 11% reduce 1%
> >>> 11/10/18 23:12:46 INFO mapred.JobClient: map 11% reduce 2%
> >>> 11/10/18 23:13:55 INFO mapred.JobClient: map 12% reduce 2%
> >>> 11/10/18 23:18:22 INFO mapred.JobClient: map 13% reduce 2%
> >>> 11/10/18 23:22:50 INFO mapred.JobClient: map 14% reduce 2%
> >>> 11/10/18 23:27:08 INFO mapred.JobClient: map 15% reduce 2%
> >>> 11/10/18 23:28:15 INFO mapred.JobClient: map 15% reduce 3%
> >>> 11/10/18 23:31:42 INFO mapred.JobClient: map 16% reduce 3%
> >>> 11/10/18 23:33:36 INFO mapred.JobClient: Task Id :
> >>> attempt_201110181002_0007_r_000000_0, Status : FAILED
> >>> java.io.IOException: Task: attempt_201110181002_0007_r_000000_0 - The
> >>> reduce copier failed
> >>> at org.apache.hadoop.mapred.ReduceTask.run(ReduceTask.java:380)
> >>> at org.apache.hadoop.mapred.Child.main(Child.java:170)
> >>> Caused by: java.io.IOException: Intermediate merge failed
> >>> at
> >>> org.apache.hadoop.mapred.ReduceTask$ReduceCopier$InMemFSMergeThread.doInMemMerge(ReduceTask.java:2576)
> >>> at
> >>> org.apache.hadoop.mapred.ReduceTask$ReduceCopier$InMemFSMergeThread.run(ReduceTask.java:2501)
> >>> Caused by: java.lang.RuntimeException: java.io.EOFException
> >>> at
> >>> org.apache.hadoop.io.WritableComparator.compare(WritableComparator.java:103)
> >>> at org.apache.hadoop.mapred.Merger$MergeQueue.lessThan(Merger.java:373)
> >>> at org.apache.hadoop.util.PriorityQueue.upHeap(PriorityQueue.java:123)
> >>> at org.apache.hadoop.util.PriorityQueue.put(PriorityQueue.java:50)
> >>> at org.apache.hadoop.mapred.Merger$MergeQueue.merge(Merger.java:447)
> >>> at org.apache.hadoop.mapred.Merger$MergeQueue.merge(Merger.java:381)
> >>> at org.apache.hadoop.mapred.Merger.merge(Merger.java:107)
> >>> at org.apache.hadoop.mapred.Merger.merge(Merger.java:93)
> >>> at
> >>> org.apache.hadoop.mapred.ReduceTask$ReduceCopier$InMemFSMergeThread.doInMemMerge(ReduceTask.java:2551)
> >>> ... 1 more
> >>> Caused by: java.io.EOFException
> >>> at java.io.DataInputStream.readByte(DataInputStream.java:250)
> >>> at org.apache.mahout.math.Varint.readUnsignedVarInt(Varint.java:159)
> >>> at org.apache.mahout.math.Varint.readSignedVarInt(Varint.java:140)
> >>> at
> >>> org.apache.mahout.math.hadoop.similarity.SimilarityMatrixEntryKey.readFields(SimilarityMatrixEntryKey.java:64)
> >>> at
> >>> org.apache.hadoop.io.WritableComparator.compare(WritableComparator.java:97)
> >>> ... 9 more11/10/18 23:33:37 INFO mapred.JobClient: map 16% reduce 0%
> >>> 11/10/18 23:35:57 INFO mapred.JobClient: map 17% reduce 0% I googled a
> >>> lot and find i should increase "mapred.reduce.tasks" property in Hadoop,
> >>> so I set it to 8 in my environment and restart this Job only, so far so
> >>> good, the job is still running by now, but it's still a little slow, so
> >>> here comes my questions: 1) does it be so slow for this job
> >>> RowSimilarityJob-Mapper-EntriesToVectorsReducer Job ?2) what does this
> >>> property "mapred.reduce.tasks" do? And why it can effect
> >>> RowSimilarityJob-Mapper-EntriesToVectorsReducer Job ? (Maybe i should ask
> >>> this 2nd question in hadoop user list... but i think people here are both
> >>> pro at hadoop :) )3) what can i do to increase the speed for this job?
> >>> Any ideas? Thanks in advance! Ramon
> >>
> >
