Hi everybody, is it possible to execute a blocking IO operation (such as HTTP GET request) in a coroutine and make it suspend instead of blocking the thread?

#coroutines or :google: 🙂

the point is I tried it and it seems the coroutines are still blocking but not suspending ... so there is still only 1 coroutine per 1 thread - the only benefit is that a coroutine starts faster, but that's it

Well to call blocking code you'll always need to "dedicate" a thread to that call.

hmh, so that means that basically if (probably) every IO operation in Java is blocking while waiting for an IO response, the coroutines can't do anything about that?

Yes. You can use a non-blocking library like

java.nio

I think.

hmh so maybe that could be the solution, I will check it, but otherwise it would have been quite pity 🙂

coroutines don't magically turn a blocking call into a non-blocking call, the blocking call will always block the thread it is on. you have to use a non-blocking version/api (like

java.nio

OR you can push the blocking call into a background thread so it doesn't block any other threads. The coroutine library makes this second option easy, since there are some blocking apis that can't be easily replaced

Well of course it is possible to do IO on coroutines, that's pretty much the point.

Thanks guys, I think that now I understand what is going on 🙂. I am going to look at the NIO Java lib just for the sake of exploration 🙂