Question

7- For each of the following systems, which deadlock strategy would you lmplement? Justity a. OS running on a student laptop (1 pt) b. OS in a self-driving car (1 pt) c. Computer that can afford a deadlock for no more than 5 minutes (2 pts)

Answer 1

Solution:-

a)

Deadlock

Deadlocks are a set of blocked processes each holding a resource and waiting to acquire a resource held by

another process.

-How to avoid these Deadlock their are four ways we can do that as follows

Mutual Exclusion

Resources shared such as read-only files do not lead to deadlocks but resources, such as printers and tape drives,

requires exclusive access by a single process.

Hold and Wait

In this condition processes must be prevented from holding one or more resources while simultaneously waiting for

other processes.

NO Preemption

Preemption of process resource allocations can avoid the condition of deadlocks, where ever possible.

Circular Wait

Circular wait can be avoided if we number all resources, and require that processes request resources only in

strictly increasing(or decreasing) order.

Handling Deadlock

Their are two strategies to avoid deadlock as follows

Preemption

We can take a resource from one process and give it to other. This will resolve the deadlock situation, but

sometimes it does causes problems.

Rollback

In situations where deadlock is a real possibility, the system can periodically make a record of the state of each

process and when deadlock occurs, roll everything back to the last checkpoint, and restart, but allocating resources

differently so that deadlock does not occur.

b)

Self-driving car also known as Automated guided vehicles

-This are used as a transportation means in many industrial fields. Taking advantage of their flexibility in routing and

scaling, AGV systems were traditionally employed in automated manufacturing systems as material handling

systems to transport pieces or parts among various workstations.

-As there are normally multiple vehicles in systems, traffic control is necessary to resolve motion conflicts among

the vehicles. In particular, vehicle collisions and deadlocks should be prevented to avoid substantial production

interruptions. Furthermore, for a system with a large number of vehicles in some applications, effective and efficient

traffic control is also important to achieve desirable system performance.

-Traditionally and still currently, Self-driving car system move along a predefined guide-path system connecting key

locations in the workspace, which eases the motion control and guidance of the vehicles, yet sets limitations on the

flexibility and scalability of the system. The literature and industrial practice have witnessed a growing interest in

developing free-ranging Self-driving car systems, in which the vehicles can choose any possible path to move

between two locations.

-This type of system is expected by some researchers to provide shorter transportation distances better utilization

of the workspace and more flexible deadlock and congestion avoidance mechanisms. However, performance

comparisons between free-ranging Self-driving car systems and those with a fixed guide-path are very rarely seen

besides, it seems that convincing conclusions have not yet been drawn on which type would perform better with

dence vehicles.

c)

-A deadlock is a condition in a system where a process cannot proceed because it needs to obtain a resource held

by another process but it itself is holding a resource that the other process needs.

-A computer system which allows more than one process to be simultaneously active, holding and requesting

resources, may encounter the phenomenon of deadlock

-Deadlock occurs so infrequently that it is not worthwhile to degrade system performance by executing prevention

algorithms. When deadlock situation arise in an online computer system, the system cannot respond within an

acceptable period of time.

-This is particularly true in process control applications, where a very quick response is required of computer

systems. According to Coffman approaches to this problem can be classified in three categories.

1) Prevention Approach

The uses of resources are restricted so that system deadlock will never occur.

2) Deadlock avoidance

Pre-claim strategy used in operating system. And not effecting in database environment.

3) Deadlock detection

If transaction is blocked is blocked due to another transaction make sure that transaction is not blocked on the first

transaction, either directly or indirectly via another transaction.