Cancelling a coroutine is "cooperative". The coroutine being canceled needs to take some steps to respond to the cancellation request, as we will see in upcoming lessons.

cancelAndJoin() cancels a coroutine and then blocks until that coroutine completes its cancellation work.

In this snippet, though, delay() cancels very quickly. As a result, the first coroutine will cancel very quickly, and so there is little additional delay introduced by using cancelAndJoin() instead of cancel(). But, if delay() were to wait for the full two seconds regardless of our cancellation request, then the second coroutine would take four total seconds to run: two seconds blocking on the first coroutine to complete cancellation, and two seconds for its own delay.

You can learn more about this in:
Tags:
cancelAndJoin() Canceling a Job Canceling a Parent Cancels Its Children Canceling and Cooperation Cooperation by Checking isActive Cooperation by Yielding Jobs Cancel When They Crash Non-Cancellable Coroutines Parent Jobs Cancel When a Child Crashes
A Conflated Channel A Fixed-Buffer Channel A Parallel Coroutine Sample A Sequential Coroutine Sample A Simple Channel A Simple Coroutine Sample A Simple Flow A Simple SharedFlow A Simple StateFlow A Zero-Buffer Channel async() BroadcastChannel cancelAndJoin() Canceling a Job Canceling a Parent Cancels Its Children Canceling and Cooperation catch() Channel and receive() Channels and Fan-out combine() Operator Contexts and Jobs Cooperation by Checking isActive Cooperation by Yielding debounce() Operator distinctUntilChanged() Operator distinctUntilChangedBy() Operator drop() Operator dropWhile() Operator filter() Operator filterIsInstance() Operator filterNot() Operator filterNotNull() Operator first() and Flow flattenConcat() Operator flattenMerge() Operator Flow Actions Flow onStart() flowOf() flowOn() Flows and Exceptions fold() Operator Hot Channels Via offer() invokeOnCompletion() Jobs and Parents Jobs Cancel When They Crash join() Lazy Coroutines map() Operator mapLatest() Operator mapNotNull() Operator Massively Parallel Coroutines MutableSharedFlow Replay Option Non-Cancellable Coroutines Parent Jobs Cancel When a Child Crashes promise() retry() retryWhen() runBlocking() sample() Operator scan() Operator single() and singleOrNull() Starting Lazy Coroutines StateFlow and Content Equality suspend Functions and Flows Suspending main() take() Operator takeWhile() Operator The Channel() Function TimeoutCancellationException Timeouts toList() and toSet() toList() for Channel withIndex() Operator withTimeoutOrNull() zip() Operator
Run Edit