Q:

Hadoop: Why I got "Max Non Heap Memory is -1 B." message in Namenode Information Web? What it does mean?

I have a cluster to use Hadoop 2.6.5 (one master that works as namenode and datanode, and two slaves) that I made using VirtualBox (easch node has Xubuntu 16.04 installed). 
A priori, the installation is right because I ran a wordcount example and it was OK. 
In master:50070 (where I see the namenode information), I get this:
"Max Non Heap Memory is -1 B." 

Do you know what does it mean? I couldn't find the answer, and I want to check it out because after running wordcount I tried to run my own program and it was not succesfull, in despite of it run OK in my single node installation of Hadoop.
I hope to be clear, please let me know if you need more information.
Thank you!

A:

Even though I haven't used Hadoop that much, when I go to the Web UI I get the same message "Max Non Heap Memory is -1 B.", as far as I know that only means that the memory usage is undefined.
Link to source of my answer

