Few weeks ago I’ve bought a new laptop and I’ve installed a new Xubuntu 11.10 on it. Surprisingly (and sadly), when I tried to connect an external display to it, I found out that it’s impossible to do it in “out of the box” version of Xubuntu. I had only a choice to use my external display instead of the internal one or to do a “mirror” configuration, having the same on both displays… Satisfying? No, thanks. I had to find out how to do it in the way I want it to work.
Just a quick tip if you try to set up Hadoop on your Ubuntu 11.10 and you wonder if Maverick’s version will work – yes, it will. Just follow the installation guide inserting this:
deb http://archive.cloudera.com/debian maverick-cdh3 contrib deb-src http://archive.cloudera.com/debian maverick-cdh3 contrib
/etc/apt/sources.list.d/cloudera.list – that’s it!
OK, not exactely – some people (I was one of them) report a
NullPointer Exception. Something similar to this:
1 2 3 4 5 6 7 8 9
Error: java.lang.NullPointerException at java.util.concurrent.ConcurrentHashMap. get(ConcurrentHashMap.java:768) at org.apache.hadoop.mapred.ReduceTask$ ReduceCopier$GetMapEventsThread. getMapCompletionEvents(ReduceTask.java:2683) at org.apache.hadoop.mapred. ReduceTask$ReduceCopier$GetMapEventsThread. run(ReduceTask.java:2605)
check your Hadoop host settings (preferrably use IP instead of hostname) and/or
/etc/hosts, which may contain a strange entry with something like
.(null) – just leave one, proper hostname in that line. For me – it started to work after this fix.
I won’t risk saying that it’ll be OK for production enviroment (production server with Ubuntu? OK…), but for testing – it works perfectly.