Hi All, I want to test the memory usage on Namenode and Datanode.
I try to use jmap, jstat, proc/pid/stat, top, ps aux, and Hadoop website interface to check the memory. The values I get from them are different. I also found that the memory always changes periodically. This is the first thing confused me. I thought the more files stored in Namenode, the more memory usage in Namenode and Datanode. I also thought the memory used in Namenode should be larger than the memory used in each Datanode. However, some results show my ideas are wrong. For example, I test the memory usage of Namenode with 6000 and 1000 files. The "6000” memory is less than “1000” memory from jmap’s results. I also found that the memory usage in Datanode is larger than the memory used in Namenode. I really don’t know how to get the memory usage in Namenode and Datanode. Can anyone give me some advices? Thanks, Tim
