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From Steve Loughran <ste...@apache.org>
Subject Re: Hadoop JobTracker Hanging
Date Tue, 22 Jun 2010 10:17:15 GMT
Bobby Dennett wrote:
> Thanks all for your suggestions (please note that Tan is my co-worker;
> we are both working to try and resolve this issue)... we experienced
> another hang this weekend and increased the HADOOP_HEAPSIZE setting to
> 6000 (MB) as we do periodically see "java.lang.OutOfMemoryError: Java
> heap space" errors in the jobtracker log. We are now looking into the
> resource allocation of the master node/server to ensure we aren't
> experiencing any issues due to the heap size increase. In parallel, we
> are also working on building "beefier" servers -- stronger CPUs, 3x more
> memory -- for the node running the primary namenode and jobtracker
> processes as well as for the secondary namenode.
> 
> Any additional suggestions you might have for troubleshooting/resolving
> this hanging jobtracker issue would be greatly appreciated.

Have you tried
  * using compressed object pointers on java 6 server? They reduce space

  * bolder: JRockit JVM. Not officially supported in Hadoop, but I liked 
using right up until oracle stopped giving away the updates with 
security patches. It has a way better heap as well as compressed 
pointers for a long time (==more stable code)

I'm surprised its the JT that is OOM-ing, anecdotally its the NN and 
2ary NN that use more, especially if the files are many and the 
blocksize small. the JT should not be tracking that much data over time

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