🍴 Dining Philosophers Deadlock Simulator

About this simulation

The dining philosophers problem, posed by Edsger Dijkstra in 1965, models a classic concurrency hazard: several processes each need two shared resources (here, forks) to make progress, but resources can only be held by one process at a time. Around a round table, each philosopher alternates between thinking and eating, but needs both the fork on their left and the fork on their right to eat.

How it works

• Naive strategy — every philosopher always reaches for their left fork first, then their right. If everyone gets hungry at once, each grabs their left fork and then waits forever for a right fork held by their neighbour — a circular wait. This is deadlock.
• Resource ordering — forks are numbered, and every philosopher must pick up the lower-numbered fork first. Because the highest-numbered philosopher reaches for a different fork first than everyone else, the circular chain is broken and deadlock becomes impossible.
• Waiter / arbitrator — a central arbitrator only allows up to N−1 philosophers to attempt picking up forks at once, guaranteeing at least one can always complete a meal and release forks for the rest.

Controls

• Philosophers — number of seats and forks around the table (3–8).
• Sim speed — how fast philosophers think and eat.
• Locking strategy — switch between naive, ordered, and waiter-arbitrated fork acquisition.
• ↺ Reset table — clears all state and restarts the simulation. Drag to rotate, scroll to zoom.

Did you know?

Deadlock requires four conditions simultaneously: mutual exclusion, hold-and-wait, no preemption, and circular wait. Breaking just one — as resource ordering does to circular wait — is enough to make deadlock structurally impossible, no matter how unlucky the scheduling gets.