Deadlock Recovery

operating-systems concurrency

Definition

Deadlock Recovery

Deadlock recovery resolves a deadlock once identified by a detection algorithm. The goal is to break the circular dependency and return the system to a safe state.

Strategies

Process Termination

Abort all deadlocked processes: Simplest but most expensive; all progress is lost.

Abort one at a time: Sequentially abort processes and rerun detection until deadlock clears.

Selection criteria:

• Least CPU time consumed
• Fewest resources held
• Lowest priority

Resource Preemption

Preempt resources: Forcibly take resources from deadlocked processes and assign them to others until the cycle breaks.

Rollback: To avoid inconsistent states, the victim must be rolled back to a previous checkpoint.

Starvation prevention: Ensure the same process is not repeatedly chosen as the victim.

Integrated Strategy

Integrated Strategy

Most operating systems combine strategies tailored to resource classes: preemption for memory, avoidance for complex I/O devices.