thank you ms. Shweta

What is a deadlock in operating system? Is it a state where two ore more operations are waiting for each other, say a computing action 'A' is waiting for action 'B' to complete, while action 'B' can only execute when 'A' is completed. Such a situation would be called a deadlock. In operating systems, a deadlock situation is arrived when computer resources required for complete of a computing task are held by another task that is waiting to execute. The system thus goes into an indefinite loop resulting into a deadlock.The deadlock in operating system seems to be a common issue in multiprocessor systems, parallel and distributed computing setups

http://www.c-sharpcorner.com/Blogs/15014/deadlock-vs-livelock.aspx

thanks munesh sharma

Two processes wating to update the rows of a table which are locked by the other process then deadlock arises. In a database environment this will often happen because of not issuing proper row lock commands. Poor design of front-end application may cause this situation and the performance of server will reduce drastically. These locks will be released automatically when a commit/rollback operation performed or any one of this processes being killed externally.