HDFS NN FSNamesystemLock throughput

[Wei Yan <yw...@gmail.com>]

Hi, guys,

Recently we're looking into HDFS NameNode FSNamesystemLock implementation.
As it uses Java's ReentrantReadWriteLock, after configing the lock to
nonfair mode, the RPC throughput has been improved a lot. Just wonder
whether anyboby have played around the reader/writer preference further in
the lock (or directly used another lock implementation) to achieve higher
throughput, absolutely there will be trade-off between throughput and write
starvation.

thanks,
Wei