Priority Inversion

Priority Inversion 
A problem in which a low priority task inadvertently does not release the process for higher priority task. An operation system can take care of this it by appropriate provisions. 

P and V semaphore

P and V semaphore 
The semaphore functions defined as mutex or counting semaphore , or to solve the classical producer- consumer problem when using a bounded buffer. 

Buffer

Buffer
A memory block for a queue or list of messages or stream of bytes between and output source and input sink, for examples, between the tasks, files, computer and printer, physical devices and network.

Counting Semaphore

Counting Semaphore
A semaphore in which the value of which can be incremented and decremented and which is not a Boolean variable. 

Mutex

Mutex
A special variable used to take note of certain actions to prevent any task or process from proceeding further and at the same time let another task exclusively proceed further. Mutex helps in mutual exclusion of one task with respect to another by a scheduler in multitasking operations. 

Semaphore

Semaphore
A special variable used to take note of certain actions to prevent another task or process from proceeding. 

Share Data Problem

Share Data Problem
If  a variable is used in two different processes and another task if interrupts without before the operation on that data is completed, the operation on that data then the scared data problem arises.