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Re: java.lang.OutOfMemoryError: GC overhead limit exceeded
Have you tried lowering mapred.job.reuse.jvm.num.tasks ?

On Sun, Sep 26, 2010 at 3:30 AM, Bradford Stephens <
[EMAIL PROTECTED]> wrote:

> Nope, that didn't seem to help.
>
> On Sun, Sep 26, 2010 at 1:00 AM, Bradford Stephens
> <[EMAIL PROTECTED]> wrote:
> > I'm going to try running it on high-RAM boxes with -Xmx4096m or so,
> > see if that helps.
> >
> > On Sun, Sep 26, 2010 at 12:55 AM, Bradford Stephens
> > <[EMAIL PROTECTED]> wrote:
> >> Greetings,
> >>
> >> I'm running into a brain-numbing problem on Elastic MapReduce. I'm
> >> running a decent-size task (22,000 mappers, a ton of GZipped input
> >> blocks, ~1TB of data) on 40 c1.xlarge nodes (7 gb RAM, ~8 "cores").
> >>
> >> I get failures randomly --- sometimes at the end of my 6-step process,
> >> sometimes at the first reducer phase, sometimes in the mapper. It
> >> seems to fail in multiple areas. Mostly in the reducers. Any ideas?
> >>
> >> Here's the settings I've changed:
> >> -Xmx400m
> >> 6 max mappers
> >> 1 max reducer
> >> 1GB swap partition
> >> mapred.job.reuse.jvm.num.tasks=50
> >> mapred.reduce.parallel.copies=3
> >>
> >>
> >> java.lang.OutOfMemoryError: GC overhead limit exceeded
> >>        at java.nio.CharBuffer.wrap(CharBuffer.java:350)
> >>        at java.nio.CharBuffer.wrap(CharBuffer.java:373)
> >>        at
> java.lang.StringCoding$StringDecoder.decode(StringCoding.java:138)
> >>        at java.lang.StringCoding.decode(StringCoding.java:173)
> >>        at java.lang.String.(String.java:443)
> >>        at java.lang.String.(String.java:515)
> >>        at
> org.apache.hadoop.io.WritableUtils.readString(WritableUtils.java:116)
> >>        at
> cascading.tuple.TupleInputStream.readString(TupleInputStream.java:144)
> >>        at
> cascading.tuple.TupleInputStream.readType(TupleInputStream.java:154)
> >>        at
> cascading.tuple.TupleInputStream.getNextElement(TupleInputStream.java:101)
> >>        at
> cascading.tuple.hadoop.TupleElementComparator.compare(TupleElementComparator.java:75)
> >>        at
> cascading.tuple.hadoop.TupleElementComparator.compare(TupleElementComparator.java:33)
> >>        at
> cascading.tuple.hadoop.DelegatingTupleElementComparator.compare(DelegatingTupleElementComparator.java:74)
> >>        at
> cascading.tuple.hadoop.DelegatingTupleElementComparator.compare(DelegatingTupleElementComparator.java:34)
> >>        at
> cascading.tuple.hadoop.DeserializerComparator.compareTuples(DeserializerComparator.java:142)
> >>        at
> cascading.tuple.hadoop.GroupingSortingComparator.compare(GroupingSortingComparator.java:55)
> >>        at
> org.apache.hadoop.mapred.Merger$MergeQueue.lessThan(Merger.java:373)
> >>        at
> org.apache.hadoop.util.PriorityQueue.downHeap(PriorityQueue.java:136)
> >>        at
> org.apache.hadoop.util.PriorityQueue.adjustTop(PriorityQueue.java:103)
> >>        at
> org.apache.hadoop.mapred.Merger$MergeQueue.adjustPriorityQueue(Merger.java:335)
> >>        at
> org.apache.hadoop.mapred.Merger$MergeQueue.next(Merger.java:350)
> >>        at org.apache.hadoop.mapred.Merger.writeFile(Merger.java:156)
> >>        at
> org.apache.hadoop.mapred.ReduceTask$ReduceCopier$InMemFSMergeThread.doInMemMerge(ReduceTask.java:2645)
> >>        at
> org.apache.hadoop.mapred.ReduceTask$ReduceCopier$InMemFSMergeThread.run(ReduceTask.java:2586)
> >>
> >> --
> >> Bradford Stephens,
> >> Founder, Drawn to Scale
> >> drawntoscalehq.com
> >> 727.697.7528
> >>
> >> http://www.drawntoscalehq.com --  The intuitive, cloud-scale data
> >> solution. Process, store, query, search, and serve all your data.
> >>
> >> http://www.roadtofailure.com -- The Fringes of Scalability, Social
> >> Media, and Computer Science
> >>
> >
> >
> >
> > --
> > Bradford Stephens,
> > Founder, Drawn to Scale
> > drawntoscalehq.com
> > 727.697.7528
> >
> > http://www.drawntoscalehq.com --  The intuitive, cloud-scale data
> > solution. Process, store, query, search, and serve all your data.
> >
> > http://www.roadtofailure.com -- The Fringes of Scalability, Social