[pjc50]

The intended use case is people trying to write realtime systems - that is, systems with a latency guarantee, like antilock brakes or flight control systems - in UNIX.

However, no sensible person would write such a thing in a general-purpose multi-user operating system. Realtime is hard, see the Toyota mess: http://www.viva64.com/en/a/0083/

"Move fast and break things" is not a great motto for automotive control software.

[amelius]

How about games, where, e.g., sound effects have a maximum acceptable delay w.r.t. the physics that generates them?

[justincormack]

Signals are not a great mechanism anyway, it turned out.

[gaius]

Well, any sort of process control too (as in, controlling an assembly line or a chemical plant).