hi, i have some questions about kotlin coroutines 1. "suspend fucntion can suspend coroutine but not block a thread", so when coroutine is suspend who is the thread responsible to execute this suspend function ?? 2. what diff between corountineContext.cancel() vs job.cancel() 3. what diff between CoroutineScope.xxx() vs suspend fun xxx()

3) By convention,

<http://CoroutineScope.xxx|CoroutineScope.xxx>()

spawns coroutines with the given scope with run even after the function returns.

suspend fun xxx()

finishes all it's work before returning.

thanks for response but is not clear 100% can you explain whats happen with this simple suspend sum function: launch { suspend sum() = (1..100).sum() } this function run in main-thread son when launch coroutne suspend sum continue exection in thread-??? how can sum() be resumed in main-thread ?

If you use

launch

it'll run the code in a background thread pool.

pool thread you mean an other thread ?? but if i log in sum() it still running in main thread

Hmm, can you use a proper code block, I don't understand what you've posted.

suspend sum() {
   println("$Thread.currentThread().name")
   (1..VAL).sum() 
}   
fun main() = runBlocking() {
   lunch {
      sum() 
  }
   println("end")
}

the program still run sequantielly and sum() still run in main-thread, so suspend here what deans if suspend function run in same thread of caller

Which platform? On jvm there is the default dispatcher, using a thread pool for all coroutines launched to it. JS and native have no threading support. So they dispatch to the main (and only) thread.

Coroutines wrapped in

runBlocking

are executed sequentially, blocking the current thread instead of suspending (hence the name). So your code is sequential and runs on the main thread only.

Use

launch(Dispatcher.Default)

to schedule to background

from javadoc

launch

If the context does not have any dispatcher nor any other [ContinuationInterceptor], then [Dispatchers.Default] is used.

runblocking

by default creates context with current thread as dispatcher, so

launch

by default will be in main thread in that example

hi devs, in kotlin coroutine "suspend functon will suspend coroutone and not block the thread" so when sum() method in execute it will be suspend coroutine (lunch) and the main-thread i not block and continue to execute rest of code, so sum () method in wich thread execute ??

As mentioned above, it depends on the dispatcher. You can pass a dispatcher to `launch`like this:

suspend sum() {
   println("$Thread.currentThread().name")
   (1..VAL).sum() 
}   
fun main() = runBlocking() {
   launch(Dispatchers.Default) {
      sum() 
  }
   println("end")
}

no i wan't to spacify any dispatcher but i just want to know about how is responsable and how exeucte a suspend funtion is running when coroutine is suspended

Hmm, I had similar confusion when I was first learning suspend functions. Given the answers to your questions are mostly "it depends", I think it'll be best if you read the informal docs as it will put you in the right frame of mind to ask/answer your questions.

@Dominaezzz thanks, you say that you have the same confusion like me so whats your conclusion ??

My conclusion was

suspend

functions are just sugar for functions with callbacks. Any question I had about coroutines or suspending stuff, I simply restructured the question to say callback instead of suspend and I had my answer.

@Dominaezzz thanks for your time