Deadlock, Livelock & Starvation

A deadlock occurs when two or more threads permanently block each other, each holding a lock the other needs, and the fix is to always acquire locks in a consistent order.

Detect deadlocks with jstack and ThreadMXBean, prevent them with lock ordering, tryLock(timeout), and ReadWriteLock.

Deadlock requires all four Coffman conditions simultaneously: mutual exclusion, hold-and-wait, no preemption, and circular wait. Breaking any one makes deadlock impossible.

Deadlock is threads BLOCKED forever in a circular lock wait (zero CPU), livelock is threads RUNNING but making no progress (high CPU, zero throughput), and starvation is a thread perpetually denied access (never gets its turn).