Chap 7 Deadlock Conditions

Question 1

Hold and wait

Answer 1

A process may hold a resource at the same time it requests another one.

Question 2

Mutual exclusion (exclusive use)

Answer 2

Once a process has been allocated a particular resource, the threads in the process have exclusive use of the resource. No other processes can use a resource while it is allocated to a process.

Question 3

Circular wait

Answer 3

 A situation can rise in which process p1 holds resource R1 while one of its threads requests resource R2, and process p2 holds R2 while one of its threads requests resource R1. There may be more than two processes involved in the circular wait.

Question 4

No preemption

Answer 4

 Resources can be released only by the explicit action in a process, rather than by the action of an external authority. This assumption includes the case in which a process places a request for a resource and the resource is not available. Then the process cannot withdraw its request.

Question 5

Addressing Deadlock - Prevention

Answer 5

Design the system so that
deadlock is impossible

Question 6

Addressing Deadlock - Avoidance

Answer 6

Construct a model of system
states, then choose a strategy that will not allow the system to go to a deadlock state

Question 7

Addressing Deadlock - Detection & Recovery

Answer 7

Check for deadlock (periodically or sporadically), then recover

Question 8

Addressing Deadlock - Manual intervention

Answer 8

Have the operator reboot the machine if it seems too slow