Any program may perform I/O operations in various forms like a file, a network , serial port or simple console operation. particularly in case of networking, sometimes individual I/O operation takes long time to complete. This poses its own kind of challenges: application development in managing CPU cycles and longer execution time etc. One option that comes to mind is to make a program multi-threaded and give the long running I/O operation to a thread. However, there is another solutions to the same problem and this is to perform I/O operations asynchronously.

There are few things to notice about asynchronous I/O over thread

• With Asynchronous code, it is known where the control will shift from one task to another; hence race conditions are harder to arrive. In case of multi-threaded program, the code needs to be safe to control race conditions. The I/O part of threaded code is comparatively easy but managing the shared state of critical section between threads (using locks/queues/etc) without race conditions is what makes it challenging. Using an asynchronous model means you have less activities going on at the same time so races can be easily avoided.