In computing, I/O module is the exchange of information
between the brain (CPU/memory combo) of computer and
the database stored in a physical disk. I/O can be divided into
two classes according to the realization of system call
function in Java language: blocking and non-blocking. In the
light of interaction between application and kernel, I/O can
be synchronous or asynchronous. In theory, asynchronous
non-blocking I/O (AIO) should have the best performance
and scalability. However, through the experiment, we find
that the performance of AIO is not better than synchronous
non-blocking I/O (NIO) on Linux, even worse sometimes.So
we finally chose the NIO technique