6.5.1 Conditions for Deadlock

(Difficulty Note: These are technical conditions. Focus on the core idea of "all waiting for each other.")

Imagine a situation where two cars (processes) are trying to cross a narrow bridge (resource). If both cars enter the bridge from opposite directions at the same time, they get stuck, and neither can move forward. This is a simple deadlock.

For a deadlock to happen, four conditions usually need to be met at the same time:

Mutual Exclusion: Only one process can use a resource at a time (like only one car can be in a specific spot on the narrow bridge).
Hold and Wait: A process is holding onto one resource (like one car is on the bridge) and waiting for another resource that is currently being held by someone else (the other car is blocking the way).
No Preemption: Resources cannot be taken away from a process once it has them (you can't just magically lift a car off the bridge).
Circular Wait: There's a circle of processes, where each process is waiting for a resource held by the next process in the circle. (Car A waits for Car B, Car B waits for Car A).

When all these conditions happen, you get a deadlock – nothing can move forward!

Bibliography:

Deadlock in Operating System. (2025, January 16). GeeksforGeeks. Retrieved July 10, 2025, from https://www.geeksforgeeks.org/operating-systems/introduction-of-deadlock-in-operating-system/
Conditions for Deadlock. (n.d.). TutorialsPoint. Retrieved July 10, 2025, from https://www.tutorialspoint.com/operating_system/conditions_for_deadlock_in_operating_system.htm