Necessary conditions for deadlocks in computing

Earlier I have described about deadlock in computing. In this article, I am going to discuss about  the necessary conditions, those hold simultaneously in a system to arise deadlock situation.

We can discuss these necessary conditions more precisely in terms of a directed graph called a system resource-allocation graph. So I used related  diagrams with description.

In this diagrams rounded rectangles visualize a resource and dots inside it visualize number of instances of the resource.Circles visualize processes.

Mutual Exclusion

In this scenario, there is a one resource(R1) with non-shareable mode. That means only one process can be used at a time. If another process requests that resource(P1), the requesting process(P1) must be wait until the resource has been released by first process(P2). 

What is deadlock in computing?

In a multi-programming environment, Processes want resources to do their corresponding process. When a process requests a resource and if it is not available at that instant, then the process enters to a waiting state. Sometimes this process can’t get out from the waiting state because the process has been hold by another process. This situation is called a deadlock. 

Let’s discuss this situation in detail.