Deadlocks

A deadlock is when two or more threads are stuck waiting for each other, with no way out. The program doesn't crash, doesn't raise, doesn't print a helpful error. It hangs. Threads that should be doing useful work sit blocked on locks they'll never get, because the threads that hold those locks are themselves blocked. This lesson covers the classic two-lock deadlock, the four conditions that make any deadlock possible, the standard ways to prevent them, and how to detect a deadlock when one shows up in production code.