Explain deadlock cases and how to prevent them

An interviewer asks you to talk about deadlocks in concurrent programming.

1. What is a deadlock?
2. Which conditions are necessary for a deadlock to occur?
3. Provide several concrete deadlock examples (such as two threads and two locks), including at least one that involves more than two locks or a circular wait.
4. In practice, how can deadlocks be prevented, avoided, detected, and/or recovered from? Describe common engineering techniques and their trade-offs. Overview: This question tests your grasp of deadlocks, concurrency control, and resource synchronization in concurrent programs. It checks whether you can state the conditions required for deadlock, work through concrete examples that include circular waits, and weigh engineering methods for prevention, detection, and recovery.