Four Situations: Name the Failure in Each

Four descriptions from four incident reports. Name the failure in each and say what would fix it. All four before the reveal.

The four incidents
	What was observed
1	Eight request threads `BLOCKED`, processor at two per cent, no progress for an hour
2	Processor at ninety per cent, two threads logging "retrying" thousands of times a second
3	Nine of ten workers finishing normally; one has not completed a task since start-up
4	Threads recover after five seconds, transfers fail under load, no hang

The four failures, and what fixes each

Each incident, the failure, and the fix
	Failure	Fix
1	Deadlock	A global lock ordering, applied everywhere both locks are taken
2	Livelock	Randomised backoff, or one thread that decides rather than both yielding
3	Starvation	A fair lock, or work-stealing so no thread depends on winning a race
4	Deadlock, with a timeout on top	Order the locks; keep the timeout as the net

Processor use separates the first two, which is why it is the first thing to look at. Idle and stuck is a cycle of locks; busy and stuck is threads reacting to each other.

The fourth is the one that gets closed as a different bug. Intermittent failures under load with no hang looks like a capacity problem, and it is the same cycle with a net under it.