This is an interesting post. My understanding: Most of the use case for async code is I/O bound operations. So you fire off a bunch of async I/O requests and wait to be notified. Logically, I/O requests normally need a timeout and/or cancel feature.
However, you raise a different point:
The tasks I'm running don't involve the network, they either succeed or error after an expensive calculation.
This sounds like CPU-bound, not I/O-bound. (Please correct me if I misunderstand.) Can you please confirm if you are using Go or a different language? If Go, I guess it still makes sense, as green threads are preferred over system threads. If not Go, I would be nice to hear more about your specific scenario. HN is a great place to learn about different use cases for a technology.
I think I just responded too hastily. I am working in Go. There is file IO going on in addition to the calculation (which because of a NAS or whatever could also be network IO). As a practical matter I had never felt the need to offer cancellation or timeout for these use cases, but I probably should, so mea culpa.
However, you raise a different point:
This sounds like CPU-bound, not I/O-bound. (Please correct me if I misunderstand.) Can you please confirm if you are using Go or a different language? If Go, I guess it still makes sense, as green threads are preferred over system threads. If not Go, I would be nice to hear more about your specific scenario. HN is a great place to learn about different use cases for a technology.