Is non-pre-emptive scheduling frequently used in a computer? Why?

No, it is rarely used for the reasons mentioned below:

- It can not ensure that each user gets a share of CPU regularly.

- The idle time with this increases reducing the efficiency and overall performance of the system.

- It allows program to run indefinitely which means that other processes have to wait for very long.

Explain condition variable.

- These are synchronization objects which help threads wait for particular conditions to occur.

- Without condition variable, the thread has to continuously check the condition which is very costly on the resources.

- Condition variable allows the thread to sleep and wait for the condition variable to give it a signal.