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From Marco Didonna <m.didonn...@gmail.com>
Subject [EC2] Could not reserve enough space for object heap
Date Sun, 11 Dec 2011 17:59:31 GMT
Hello everyone,
I'm running a small toy cluster (3 nodes) on EC2 configured as follows:

* one node as JT+NN
* two nodes as DN+TT

I use whirr to build such cluster on demand (config file here
http://pastebin.com/JXHYvMNb). Since my jobs are memory intensive I'd
like to exploit the 8GB of ram the m1.large instance offers. Thus I
added mapred.map.child.java.opts=-Xmx1g and
mapred.reduce.child.java.opts=-Xmx1g (adding just
hadoop-mapreduce.mapred.child.java.opts=-Xmx1g produced no effect
since the map tasks were allocated the default 200MB). The problem is
that with these settings I cannot have any job running because I
always get

1/12/11 18:14:24 INFO mapred.JobClient: Running job: job_201112111644_0002
11/12/11 18:14:25 INFO mapred.JobClient:  map 0% reduce 0%
11/12/11 18:14:28 INFO mapred.JobClient: Task Id :
attempt_201112111644_0002_m_000004_0, Status : FAILED
java.lang.Throwable: Child Error
	at org.apache.hadoop.mapred.TaskRunner.run(TaskRunner.java:242)
Caused by: java.io.IOException: Task process exit with nonzero status of 1.
	at org.apache.hadoop.mapred.TaskRunner.run(TaskRunner.java:229)

11/12/11 18:14:28 WARN mapred.JobClient: Error reading task
outputip-10-87-1-170.ec2.internal
11/12/11 18:14:28 WARN mapred.JobClient: Error reading task
outputip-10-87-1-170.ec2.internal
11/12/11 18:14:30 INFO mapred.JobClient: Task Id :
attempt_201112111644_0002_r_000001_0, Status : FAILED
java.lang.Throwable: Child Error
	at org.apache.hadoop.mapred.TaskRunner.run(TaskRunner.java:242)
Caused by: java.io.IOException: Task process exit with nonzero status of 1.
	at org.apache.hadoop.mapred.TaskRunner.run(TaskRunner.java:229)

And the only log I can get from the job_201112111644_0002 is the
stdout and the stderr whose combined output is

Could not create the Java virtual machine.
Error occurred during initialization of VM
Could not reserve enough space for object heap

I really cannot understand why the jvm cannot allocate enough space:
there's plenty of ram. I also tried to reduce the number of map slots
to two: nothing changed. I'm out of ideas. I hope you can shed some
light :)

FYI I use cloudera distribution for hadoop, latest stable release available.

Thanks for your attention.

MD

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