What is a deadlock?

A deadlock occurs when two or more processes are waiting for each other to release resources they need to continue. This results in a situation where none of the processes can proceed, and they end up waiting indefinitely.

🔹 Coffman Conditions

The Coffman conditions, named after Edward G. Coffman, Jr., who first described them in 1971, outline four necessary conditions that must all be present for a deadlock to occur:

- Mutual Exclusion: Resources cannot be shared simultaneously

- Hold and Wait: Processes hold resources while waiting for others

- No Preemption: Resources cannot be forcibly taken away

- Circular Wait: A circular chain of processes, each waiting for a resource held by the next

🔹 Deadlock Prevention

- Resource ordering: Require processes to request resources in a specific order

- Timeouts: Set time limits for resource usage to prevent indefinite holds

- Banker's Algorithm: A method that checks if granting a resource request would lead to a safe state

🔹 Deadlock Recovery

- Selecting a victim: Choose one or more processes to terminate or roll back

- Rollback: Undo the actions of the selected process(es) to free up resources

Have you encountered any challenging deadlock situations? How did you resolve them?

cr. Sahn Lam