from Hacker News

Durable Coroutines for Go

by greenSunglass on 10/19/23, 6:45 AM with 35 comments

by kitd on 10/20/23, 6:34 PM
Impressive work. This reminds me of an experimental JVM that was around about 20 years ago from a group called Velare. They could do durable coroutines just like this, but by throwing a particular exception rather than using `yield`. They also could return a value and allow the coro to be resumed with a value.
edit: here it is https://dl.acm.org/doi/10.1145/949344.949362 It was a built-in bytecode interpreter with suspendable threads
It changed significantly how you think about cooperating processes. It was like watching 2 processes have a conversation with each other without the controlling code getting involved in any way. Also, if you save the coros after each call, you can get step-by-step replays which are very helpful in debugging.
by skybrian on 10/20/23, 7:00 PM
The saved coroutine state is an implicitly-defined data structure and they don’t support any kind of migration when the code changes, so the durability will be quite limited.
by tedunangst on 10/20/23, 6:23 PM
This seems really brittle.
https://github.com/stealthrocket/coroutine/blob/main/getg_am...
by hnav on 10/20/23, 8:27 PM
I feel like once serializing god-knows-what state across program invocations is a requirement, I'd much prefer writing this explicitly so I can at least have a chance of debugging it
```
  type Task struct {
    I int
  }

  func (t *Task) Next() (bool, int) {
    if t.I < 3 {
      return t.I++, true
    }
    return 0, false
  }

  var t Task
  t.Next()
  json.Marshal(t)
```
by zellyn on 10/20/23, 8:30 PM
A succinct explanation of how durable coroutines are different (in practice) from Temporal would be useful.
by ctvo on 10/21/23, 5:21 PM
From a user perspective: how is this different than what Temporal provides?
by born-jre on 10/20/23, 7:09 PM
nice, but i had a separate idea.
what if u build a wasm runtime that can save and restore memory with and execution states, sounds much more full proof. or i might have misunderstood this idea :D.
by infogulch on 10/20/23, 6:33 PM
Why are channels insufficient for this use case?
by varispeed on 10/20/23, 9:48 PM
Why not fork Go and implement this directly? (and also removing any telemetry Google might have installed while at it...)
by zelly on 10/21/23, 3:09 AM
This is the kind of thing you can only trust the compiler to do. And we already have goroutines.
by rweir on 10/20/23, 10:08 PM
very cool - looking forward to seeing the rest.