Reading the “Kotlin Coroutines” book, it just dawned on me that `CoroutineContext` is basically the ...

# coroutines

[Alexander Maryanovsky]

Reading the “Kotlin Coroutines” book, it just dawned on me that CoroutineContext is basically the coroutines’ equivalent of ThreadLocal. Why don’t the tutorials say this? Would make understanding so much faster…

[Sam]

https://elizarov.medium.com/phantom-of-the-coroutine-afc63b03a131

[Sam]

I think the two paradigms (threads vs coroutines) are different enough that drawing that comparison might just create more confusion

[Alexander Maryanovsky]

I agree, it’s not equivalent. Maybe “similar” is better.

[Alexander Maryanovsky]

I was just completely confused as to what a coroutine context was until the parallel to threadlocal dawned on me.

[Alexander Maryanovsky]

Not sure I agree with that article. Can’t you think of the chain of `Continuation`s are the coroutine?

[Sam]

You'd have to take that up with Roman 😄. He probably knows what he's talking about, though, he was the project lead on coroutines and now on all of Kotlin

[Sam]

If I had to take a stab at an answer, I'd say that the chain of continuations is to the coroutine as the call stack is to the thread

[Alexander Maryanovsky]

Yes. But what is a thread if not its call stack + a record somewhere in the thread scheduler?

[Sam]

Actually here is a StackOverflow post, also from Roman, where he says that "Coroutine's analog to ThreadLocal is `CoroutineContext`". So maybe this is something that could be mentioned in the documentation. I agree with you that it would give a good starting point for understanding, even if the comparison is inexact.