4 ms·

async/await and channel are independent of scheduling. Nodejs doesn't have multithread but has async/await. I find goroutines lightweight enough in my personal

async/await and channel are independent of scheduling. Nodejs doesn't have multithread but has async/await. I find goroutines lightweight enough in my personal testing and didn't tried tweaking it.

pjmlp 6y ago
On .NET and C++ they surely are not, given that you can fine tune them either by providing new schedulers, magic methods on awaitable objects that can be either value or reference types. So not only you can control the scheduling algorithm, you can control how the async/await state gets managed in memory and also introduce additional parameters that influence the decision when to switch tasks across owner threads. Try to do this in Go via channels, while offering just the channel syntax to the caller. EDIT: The only thing in common between JavaScript, Python, .NET, C++ and Kotlin async/await is the name of the primitives.
- unscaled 6y ago
  Custom stackless coroutine schedulers are also available in Kotlin. Python also also allows you to customize the event loop, I think, but overriding AbstractEventLoop. A M:N implementation would probably be inefficient though because of the GIL. Basically almost all stackless implementations I know allow for custom scheduling. The fact that some of them can't do M:N and are restricted to 1:N is just a limitation of dynamic programming languages. There is a global interpreter state which prevents you from using multiple OS threads efficiently. You either rely on GIL (CPython and Ruby MRI) or rely on just allow only one thread (Node, Lua). So GP is right in that not _all_ async/await implementations will allow you to fully customize your threads but I think the main point here is that stackless coroutines are practically _a prerequisite_ for enabling custom scheduling (like C# et. al allow). You cannot have this custom scheduling with stackful coroutines, because that would require the scheduler to have access to low level memory management for controlling the stack. I've never seen a language which allows that. I guess this could be doable on C++, but I really don't see the point, since it will require a lot more effort than the current stackless C++ coroutines.
  - pjmlp 6y ago
    That is my whole point, this is not doable with Go channels alone as primitive.
    - gpderetta 6y ago
      Yes, that's not a good primitive. You need some delimited form of call/cc.
  - gpderetta 6y ago
    > I've never seen a language which allows that. It is not really hard. You can use the exact same scheduler you would use for stackless coroutines. For example in C++ land you can use boost.asio to schedule both stackless coroutines and boost.fibers (or whatever have you). Boost.asio predates both and doesn't care.

async/await and channel are independent of scheduling. Nodejs doesn't have multithread but has async/await. I find goroutines lightweight enough in my personal testing and didn't tried tweaking it.

pjmlp 6y ago

On .NET and C++ they surely are not, given that you can fine tune them either by providing new schedulers, magic methods on awaitable objects that can be either value or reference types. So not only you can control the scheduling algorithm, you can control how the async/await state gets managed in memory and also introduce additional parameters that influence the decision when to switch tasks across owner threads. Try to do this in Go via channels, while offering just the channel syntax to the caller. EDIT: The only thing in common between JavaScript, Python, .NET, C++ and Kotlin async/await is the name of the primitives.

unscaled 6y ago
Custom stackless coroutine schedulers are also available in Kotlin. Python also also allows you to customize the event loop, I think, but overriding AbstractEventLoop. A M:N implementation would probably be inefficient though because of the GIL. Basically almost all stackless implementations I know allow for custom scheduling. The fact that some of them can't do M:N and are restricted to 1:N is just a limitation of dynamic programming languages. There is a global interpreter state which prevents you from using multiple OS threads efficiently. You either rely on GIL (CPython and Ruby MRI) or rely on just allow only one thread (Node, Lua). So GP is right in that not _all_ async/await implementations will allow you to fully customize your threads but I think the main point here is that stackless coroutines are practically _a prerequisite_ for enabling custom scheduling (like C# et. al allow). You cannot have this custom scheduling with stackful coroutines, because that would require the scheduler to have access to low level memory management for controlling the stack. I've never seen a language which allows that. I guess this could be doable on C++, but I really don't see the point, since it will require a lot more effort than the current stackless C++ coroutines.
- pjmlp 6y ago
  That is my whole point, this is not doable with Go channels alone as primitive.
  - gpderetta 6y ago
    Yes, that's not a good primitive. You need some delimited form of call/cc.
- gpderetta 6y ago
  > I've never seen a language which allows that. It is not really hard. You can use the exact same scheduler you would use for stackless coroutines. For example in C++ land you can use boost.asio to schedule both stackless coroutines and boost.fibers (or whatever have you). Boost.asio predates both and doesn't care.