what is deadlock?

Question

what is deadlock?

Answer 1

The condition in which two or more processes are blocked, each waiting for a lock held by the other. Deadlock is prevented by the rule that a driver upper-half entry point is not allowed to hold a lock while sleeping.



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Answer 2

A deadlock is a situation wherein two or more competing actions are waiting for the other to finish, and thus neither ever does. It is often seen in a paradox like 'the chicken or the egg'.



In the computing world deadlock refers to a specific condition when two or more processes are each waiting for another to release a resource, or more than two processes are waiting for resources in a circular chain (see Necessary conditions). Deadlock is a common problem in multiprocessing where many processes share a specific type of mutually exclusive resource known as a software, or soft, lock. Computers intended for the time-sharing and/or real-time markets are often equipped with a hardware lock (or hard lock) which guarantees exclusive access to processes, forcing serialization. Deadlocks are particularly troubling because there is no general solution to avoid (soft) deadlocks.

This situation may be likened to two people who are drawing diagrams, with only one pencil and one ruler between them. If one person takes the pencil and the other takes the ruler, a deadlock occurs when the person with the pencil needs the ruler and the person with the ruler needs the pencil, before he can give up the ruler. Both requests can't be satisfied, so a deadlock occurs.

Answer 3

A condition that occurs when two processes are each waiting for the other to complete before proceeding. The result is that both processes hang. Deadlocks occur most commonly in multitasking and client/server environments

Answer 4

A deadlock is a situation wherein two or more competing actions are waiting for the other to finish, and thus neither ever does.

Answer 5

Deadlock Occurs when two or more separate processes compete for resources held by one another.

For example take two process P1,P2.

and two resourses R1,R2,R3.

P1 is using R1,R2 and P2 is using R1,R3 and

P1 is need of R3 to complete the process and

P2 is need of R2 to complete. So P1 ll compete to take R3 and P2 ll compete take R2.

But P1 ll leave R2 only on completion of it process and P2 ll leave R3 on completion of its process.

So there s lock of resources between P1 and P3.

Hence this is deadlock.



To avoid deadlock there are many algorithms