> These days you'd implement cancellation by having one thread handle inbound messages and another thread do the actual work with shared memory to implement a c

> These days you'd implement cancellation by having one thread handle inbound messages and another thread do the actual work with shared memory to implement a cooperative cancellation mechanic. Doesn't necessarily need a thread per connection. Could be on an epoll/kqueue/io-uring. The query would need to periodically re-check a cancellation flag, which has costs and would come with a delay if it's particularly busy.