6.7 Deadlock recovery

When a deadlock is detected, two approaches can be done. One approach aborts one or more processes to break the circular wait. The other approach preempts some resources from one or more of the deadlocked processes.

Process termination
Aborting processes to eliminate deadlocks can be done in one of two methods:

Abort all deadlocked processes.

Abort one process at a time until the deadlock cycle is eliminated. The order in which the processes will

be aborted can be according to the following factors:

Priority of the process

How long process has computed, and how much longer to completion

Resources the process has used

Resources process needs to complete

How many processes will need to be terminated

Is process interactive or batch?

6.7 Deadlock recovery

Resource preemption
If resource preemption is required to deal with deadlocks, then three issues need to be addressed:

Selecting a victim: The order of processes to be aborted has to be chosen to minimize the cost.

Rollback: The aborted process must be rolled back to some safe state and restart it from that state.

Starvation: We need to guarantee that the same process will not be always picked as victim.