Deadlock Characteristics

Deadlock Characteristics

Necessary Condition for Deadlock

• Following four conditions are necessary for deadlock to exist.

1. Mutual exclusion

2. No preemption

3. Hold and wait

4. Circular wait

1. Mutual exclusion: A resource may be acquired exclusively by only one process at a time.

2. Hold and wait: Processes currently holding resources that were granted earlier can request new resources.

3. No preemption: Once a process has obtained a resource, the system cannot remove it from the process control until the process has finished using the

4. Circular wait: A circular chain of hold and wait condition exists in the system. All four of these conditions must be present for a resource deadlock to occur. If one of them is absent, no resource deadlock is possible.