Hi Danny,
please send all mails to [email protected] instead of directly
sending them to me, there are a lot of smart people on that list that
might join with advice.
I'm very excited that you intensively test this code and I'm positively
suprised to see it give good results. Thank you for the effort you put
into that!
The exception seems to occur when ALSEvaluator is run. The code uses a
quick and dirty approach to compute the error of the model as it just
loads the user and item feature matrices completely into memory. With an
increasing number of features memory consumption is getting too large.
The code of that evaluator step needs to be changed, so that each
(user,item) pair for which the rating shall be predicted gets joined
with the according user and item feature vectors in a way that they are
mapped to the same key and go to the same reducer which can then compute
the error.
I already started implementing something like this, but I don't have a
lot of time these days unfortunately. I could update the patch during
the next week if that's ok for you.
--sebastian
On 23.02.2011 21:57, Danny Bickson wrote:
Another exception I am getting:
11/02/23 20:45:34 INFO common.AbstractJob: Command line arguments:
{--endPhase=2147483647, --itemFeatures=/tmp/als/out/M/
, --probes=/user/ubuntu/myout/probeSet/, --startPhase=0, --tempDir=temp,
--userFeatures=/tmp/als/out/U/}
Exception in thread "main" java.lang.OutOfMemoryError: Java heap space
at
org.apache.mahout.math.map.OpenIntDoubleHashMap.rehash(OpenIntDoubleHashMap.java:433)
at
org.apache.mahout.math.map.OpenIntDoubleHashMap.put(OpenIntDoubleHashMap.java:387)
at
org.apache.mahout.math.RandomAccessSparseVector.setQuick(RandomAccessSparseVector.java:134)
at
org.apache.mahout.math.VectorWritable.readFields(VectorWritable.java:113)
at
org.apache.hadoop.io.SequenceFile$Reader.getCurrentValue(SequenceFile.java:1751)
at
org.apache.hadoop.io.SequenceFile$Reader.next(SequenceFile.java:1879)
at
org.apache.mahout.utils.eval.ALSEvaluator.readMatrix(ALSEvaluator.java:113)
at
org.apache.mahout.utils.eval.ALSEvaluator.run(ALSEvaluator.java:71)
at org.apache.hadoop.util.ToolRunner.run(ToolRunner.java:65)
at org.apache.hadoop.util.ToolRunner.run(ToolRunner.java:79)
at
org.apache.mahout.utils.eval.ALSEvaluator.main(ALSEvaluator.java:52)
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.ProgramDriver$ProgramDescription.invoke(ProgramDriver.java:68)
at
org.apache.hadoop.util.ProgramDriver.driver(ProgramDriver.java:139)
at org.apache.mahout.driver.MahoutDriver.main(MahoutDriver.java:174)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at
sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
at
sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:616)
at org.apache.hadoop.util.RunJar.main(RunJar.java:156)
THANKS!
---------- Forwarded message ----------
From: *Danny Bickson* <[email protected]
<mailto:[email protected]>>
Date: Wed, Feb 23, 2011 at 3:05 PM
Subject: Another mahout ALS question
To: [email protected] <mailto:[email protected]>
Hi!
I successfully run 10 iterations for your ALS code, with D=20,
lambda=0.065 and I get a very impressive RMSE of 0.93
However, when I try to increase D, I get various out of memory errors,
even with small netflix subsample of 3M values.
One of the errors I am getting is in the evaluateALS step:
11/02/23 19:04:11 WARN driver.MahoutDriver: No evaluateALS.props found
on classpath, will use command-line arguments only
11/02/23 19:04:12 INFO common.AbstractJob: Command line arguments:
{--endPhase=2147483647, --itemFeatures=/tmp/als/out/M/,
--probes=/user/ubuntu/myout/probeSet/, --startPhase=0, --tempDir=temp,
--userFeatures=/tmp/als/out/U/}
Exception in thread "main" java.lang.OutOfMemoryError: GC overhead limit
exceeded
at
org.apache.mahout.math.map.OpenIntDoubleHashMap.rehash(OpenIntDoubleHashMap.java:433)
at
org.apache.mahout.math.map.OpenIntDoubleHashMap.put(OpenIntDoubleHashMap.java:387)
at
org.apache.mahout.math.RandomAccessSparseVector.setQuick(RandomAccessSparseVector.java:134)
at
org.apache.mahout.math.VectorWritable.readFields(VectorWritable.java:113)
at
org.apache.hadoop.io.SequenceFile$Reader.getCurrentValue(SequenceFile.java:1751)
at
org.apache.hadoop.io.SequenceFile$Reader.next(SequenceFile.java:1879)
at
org.apache.mahout.utils.eval.ALSEvaluator.readMatrix(ALSEvaluator.java:113)
at
org.apache.mahout.utils.eval.ALSEvaluator.run(ALSEvaluator.java:71)
at org.apache.hadoop.util.ToolRunner.run(ToolRunner.java:65)
at org.apache.hadoop.util.ToolRunner.run(ToolRunner.java:79)
at
org.apache.mahout.utils.eval.ALSEvaluator.main(ALSEvaluator.java:52)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at
sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
at
sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:616)
at
org.apache.hadoop.util.ProgramDriver$ProgramDescription.invoke(ProgramDriver.java:68)
at
org.apache.hadoop.util.ProgramDriver.driver(ProgramDriver.java:139)
at
org.apache.mahout.driver.MahoutDriver.main(MahoutDriver.java:174)
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)
There is no related exception in the Hadoop logs.
I am running with java child opts of -Xmx2048M.
Do you have any tips for me? Do you want me to post this into the
Mahout-542 newsgroup?
thanks,
DB
