Namenode - RPC processing

[krish ws <kr...@gmail.com>]

Hi,
    I was reading a online blog about how the RPC requests from hdfs
clients gets processed where a listener object on the name node accepts
connections after which the RPC thread read those requests and add them to
call queue. Then the worker thread kick in and does the following:

>> first grab the write lock for the namespace
>> change the in-memory namespace
>> writes to the in-memory FSEdits log
>> releases write lock on namespace

I am having a bit trouble understanding the above four operations, request
if someone can provide some insights into the above.

Thanks & appreciate it
Krish