State the recovery methods after the deadlock is defected.
Answer on Question
Statethe recovery methods after the deadlock is defected.
Thereare three basic approaches to recovery from deadlock: 1. Inform the system operator,and allow him/her to take manual intervention. 2. Terminate one or moreprocesses involved in the deadlock 3. Preempt resources.
Twobasic approaches, both of which recover resources allocated to terminated processes: · Terminateall processes involved in the deadlock. This definitely solves the deadlock, but at the expense of terminating more processes than would be absolutely necessary. · Terminateprocesses one by one until the deadlock is broken. This is more conservative, but requires doing deadlock detection after each step.
Whenpreempting resources to relieve deadlock, there are three important issues to be addressed: · Selectinga victim - Deciding which resources to preempt from which processes involves many of the same decision criteria outlined above. · Rollback- Ideally one would like to roll back a preempted process to a safe state prior to the point at which that resource was originally allocated to the process. Unfortunately it can be difficult or impossible to determine what such a safe state is, and so the only safe rollback is to roll back all the way back to the beginning.