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From Matei Zaharia <ma...@cloudera.com>
Subject Re: Could not reserve enough space for heap in JVM
Date Thu, 26 Feb 2009 05:31:13 GMT
Yes, the namenode, jobtracker, datanode, etc are separate processes.
Typically in a large cluster you'd have one machine running a namenode, one
running a jobtracker, and many slave machines running a datanode and
tasktracker. The datanodes and tasktrackers don't need high amounts of
memory. The namenode needs more if you have a large filesystem (large
numbers of files), and the jobtracker needs more if you have many large jobs
(tens of thousands of tasks). However these should not be problems on
smaller clusters. The child memory settings are the ones to fix if your
tasks are failing.

On Wed, Feb 25, 2009 at 9:27 PM, Arijit Mukherjee <arijit72@gmail.com>wrote:

> Mine is 32bit. As of now, it has only 2GB RAM, but I'm planning to acquire
> more hardware resources - so a clarification in this regard would help me
> in
> deciding the specs of the new cluster.
>
> Arijit
>
> 2009/2/26 souravm <SOURAVM@infosys.com>
>
> > Is ur machine 32 bit or 64 bit
> >
> > ----- Original Message -----
> > From: Nick Cen <cenyongh@gmail.com>
> > To: core-user@hadoop.apache.org <core-user@hadoop.apache.org>
> > Sent: Wed Feb 25 21:10:00 2009
> > Subject: Re: Could not reserve enough space for heap in JVM
> >
> > I got a question relatived to the HADOOP_HEAPSIZE variable. My machine's
> > memory size is 16G. but when i set HADOOP_HEAPSIZE to 4GB, it thrown the
> > exception refered in this thread. how can i make full use of my mem. thx.
> >
> > 2009/2/26 Arijit Mukherjee <arijit72@gmail.com>
> >
> > > I was getting similar errors too while running the mapreduce samples. I
> > > fiddled with the hadoop-env.sh (where the HEAPSIZE is specified) and
> the
> > > hadoop-site.xml files - and rectified it after some trial and error.
> But
> > I
> > > would like to know if there is a thumb rule for this. Right now, I've a
> > > core
> > > duo machine with 2GB RAM running on Ubuntu 8.10, and I've found that a
> > > HEAPSIZE of 256Mb works without any problems. Anything more than that
> > would
> > > give the same error (even when nothing else is going on in the
> machine).
> > >
> > > Arijit
> > >
> > > 2009/2/26 Anum Ali <miss.anumali@gmail.com>
> > >
> > > > If the solution given my Matei Zaharia wont work , which I guess it
> > > > wont if you are using eclipse 3.3.0 because this is a bug , which
> they
> > > > resloved it in later version which is eclipse 3.4 ganymede. Better
> > > > upgrade eclipse version.
> > > >
> > > >
> > > >
> > > >
> > > > On 2/26/09, Matei Zaharia <matei@cloudera.com> wrote:
> > > > > These variables have to be at runtime through a config file, not
at
> > > > compile
> > > > > time. You can set them in hadoop-env.sh: Uncomment the line with
> > export
> > > > > HADOOP_HEAPSIZE=<whatever> to set the heap size for all Hadoop
> > > processes,
> > > > or
> > > > > change options for specific commands. Now these commands are for
> the
> > > > Hadoop
> > > > > processes themselves, but if you are getting the error in tasks
> > you're
> > > > > running, you can set these in your hadoop-site.xml through the
> > > > > mapred.child.java.opts variable, as follows:
> > > > > <property>
> > > > >   <name>mapred.child.java.opts</name>
> > > > >   <value>-Xmx512m</value>
> > > > > </property>
> > > > >
> > > > > By the way I'm not sure if -J-Xmx is the right syntax; I've always
> > seen
> > > > -Xmx
> > > > > and -Xms.
> > > > >
> > > > > On Wed, Feb 25, 2009 at 5:05 PM, madhuri72 <akilzer@gmail.com>
> > wrote:
> > > > >
> > > > >>
> > > > >> Hi,
> > > > >>
> > > > >> I'm trying to run hadoop version 19 on ubuntu with java build
> > > > >> 1.6.0_11-b03.
> > > > >> I'm getting the following error:
> > > > >>
> > > > >> Error occurred during initialization of VM
> > > > >> Could not reserve enough space for object heap
> > > > >> Could not create the Java virtual machine.
> > > > >> make: *** [run] Error 1
> > > > >>
> > > > >> I searched the forums and found some advice on setting the VM's
> > memory
> > > > via
> > > > >> the javac options
> > > > >>
> > > > >> -J-Xmx512m or -J-Xms256m
> > > > >>
> > > > >> I have tried this with various sizes between 128 and 1024 MB.
 I
> am
> > > > adding
> > > > >> this tag when I compile the source.  This isn't working for me,
> and
> > > > >> allocating 1 GB of memory is a lot for the machine I'm using.
 Is
> > > there
> > > > >> some
> > > > >> way to make this work with hadoop?  Is there somewhere else I
can
> > set
> > > > the
> > > > >> heap memory?
> > > > >>
> > > > >> Thanks.
> > > > >>
> > > > >>
> > > > >>
> > > > >>
> > > > >>
> > > > >> --
> > > > >> View this message in context:
> > > > >>
> > > >
> > >
> >
> http://www.nabble.com/Could-not-reserve-enough-space-for-heap-in-JVM-tp22215608p22215608.html
> > > > >> Sent from the Hadoop core-user mailing list archive at Nabble.com.
> > > > >>
> > > > >>
> > > > >
> > > >
> > >
> > >
> > >
> > > --
> > > "And when the night is cloudy,
> > > There is still a light that shines on me,
> > > Shine on until tomorrow, let it be."
> > >
> >
> >
> >
> > --
> > http://daily.appspot.com/food/
> >
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> --
> "And when the night is cloudy,
> There is still a light that shines on me,
> Shine on until tomorrow, let it be."
>

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