Sometime, for many computer applications, a process needs exclusive access to several resources.
Let's suppose, for eg., there are two processes and each want to record a scanned document on a Pen drive. Process X requests permission to use the scanner and is granted it. And process Y is programmed differently and requests the Pen drive recorder first and is also granted it. Now X asks for the Pen drive recorder, but the request is denied until Y releases it.
Now, instead of releasing the Pen drive recorder Y asks for the scanner. At this point, both processes are blocked and will remain for forever. This situation is called as Deadlock.
Deadlocks sometime can also occur across computer machines. For eg., many offices have LAN (Local Area Network) connected with multiple computers.
Often devices such as scanners, DVD recorders, printers, and tape drives are connected to the network as shared resources, available to any user on any machine.
Now, unfortunately, all these devices can be reserved remotely, then this situation is also called as deadlock.
You will learn all about deadlocks in operating system in detail, divided into following tutorials: