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Re: rack awareness in hadoop
And don't forget to look at unlimit settings as well

Sent from my iPhone

On Apr 20, 2013, at 5:07 PM, Marcos Luis Ortiz Valmaseda <[EMAIL PROTECTED]> wrote:

> Like, Aaron say, this problem is related the Linux memory manager.
> You can tune it using the vm.overcommit_memory=1.
> Before to do any change, read all resources first:
> http://www.thegeekstuff.com/2012/02/linux-memory-swap-cache-shared-vm/
> http://www.oracle.com/technetwork/articles/servers-storage-dev/oom-killer-1911807.html
> http://lwn.net/Articles/317814/
> http://www.tldp.org/LDP/tlk/mm/memory.html
> To learn more about how to tune kernel variables for Hadoop applications. Read these links too:
> First, the amazing Hadoop Operations´s book from Eric:
> http://my.safaribooksonline.com/book/databases/hadoop/9781449327279/4dot-planning-a-hadoop-cluster/id2685120
> Hadoop Performance Tuning Guide from AMD:
> http://developer.amd.com.php53-23.ord1-1.websitetestlink.com/wordpress/media/2012/10/Hadoop_Tuning_Guide-Version5.pdf
> Intel® Distribution for Apache Hadoop*  Software: Optimization and Tuning Guide:
> http://hadoop.intel.com/pdfs/IntelDistributionTuningGuide.pdf
> Best wishes.
> 2013/4/20 Aaron Eng <[EMAIL PROTECTED]>
>> The problem is probably not related to the JVM memory so much as the Linux memory manager.  The exception is in java.lang.UNIXProcess.<init>(UNIXProcess.java:148) which would imply this is happening when trying to create a new process.  The initial malloc for the new process space is being denied by the memory manager.  There could be many reasons why this happens, though the most likely is your overcommit settings and swap space.  I'd suggest reading through these details:
>> https://www.kernel.org/doc/Documentation/vm/overcommit-accounting
>> On Sat, Apr 20, 2013 at 4:00 PM, Kishore Yellamraju <[EMAIL PROTECTED]> wrote:
>>> All,
>>> I have posted this question to CDH ML ,  but i guess i can post it here because its a general hadoop question.
>>> When the NN or JT gets the rack info, i guess it stores the info in memory. can i ask you where in the JVM memory it will store the results ( perm gen ?) ? .  I am getting "cannot allocate memory on NN and JT " and they have more than enough memory. when i looked at JVM usage stats i can see it doesnt have enough perm free space.so if its storing the values in perm gen  then there is a chance of this memory issues.
>>> Thanks in advance !!!
>>> exception that i see in logs :
>>> java.io.IOException: Cannot run program "/etc/hadoop/conf/topo.sh" (in directory "/usr/lib/hadoop-0.20-mapreduce"): java.io.IOException: error=12, Cannot allocate memory
>>>         at java.lang.ProcessBuilder.start(ProcessBuilder.java:459)
>>>         at org.apache.hadoop.util.Shell.runCommand(Shell.java:206)
>>>         at org.apache.hadoop.util.Shell.run(Shell.java:188)
>>>         at org.apache.hadoop.util.Shell$ShellCommandExecutor.execute(Shell.java:381)
>>>         at org.apache.hadoop.net.ScriptBasedMapping$RawScriptBasedMapping.runResolveCommand(ScriptBasedMapping.java:242)
>>>         at org.apache.hadoop.net.ScriptBasedMapping$RawScriptBasedMapping.resolve(ScriptBasedMapping.java:180)
>>>         at org.apache.hadoop.net.CachedDNSToSwitchMapping.resolve(CachedDNSToSwitchMapping.java:119)
>>>         at org.apache.hadoop.mapred.JobTracker.resolveAndAddToTopology(JobTracker.java:2750)
>>>         at org.apache.hadoop.mapred.JobInProgress.createCache(JobInProgress.java:593)
>>>         at org.apache.hadoop.mapred.JobInProgress.initTasks(JobInProgress.java:765)
>>>         at org.apache.hadoop.mapred.JobTracker.initJob(JobTracker.java:3775)
>>>         at org.apache.hadoop.mapred.EagerTaskInitializationListener$InitJob.run(EagerTaskInitializationListener.java:90)
>>>         at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886)
>>>         at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908)