Java's nonblocking I/O

Java NIO (New IO) is a nonblocking I/O API for Java. This NIO is an alternative to the standard Java I/O API. It provides abstractions such as channels, buffers, and selectors. The idea is to provide an implementation that can use the most efficient operations provided by the operating system, as shown in the following screenshot:

A channel is just a bidirectional I/O stream. A single thread can monitor all the channels an application has opened. Data arriving at any channel is an event, and the listening thread is notified of its arrival.

The selector uses event notification: a thread can then check whether the I/O is complete without any need for blocking. A single thread can handle multiple concurrent connections.

This translates into two primary benefits:

• Overall, you would need fewer threads. As a thread has a memory footprint, the memory management would have less overhead.
• Threads could do something useful when there is no I/O. This opens up the possibility of optimization, as threads are a valuable resource.

The Netty framework (https://netty.io/) is an NIO-based client-server framework. The Play framework is a high-performance, reactive web framework based on Netty.