A modern programming language that makes developers happier.

kotlinlang

Another possibility might be
```    val coroJob = AtomicReference&lt;Job&gt; ()
    /// Start my coroutine, may be called from any thread
    fun startCoro () {

        val coro = coroutineScope.launch(<http://Dispatchers.IO|Dispatchers.IO>, start = LAZY) {
            // Do the actual work here ...
            coroJob.set(null)
        }

        // If coroJob isn't null, do nothing.
        if (coroJob.compareAndSet(null, coro))
            coro.start()
    }```
which avoids the explicit context switches and should still be thread-safe. Is there a more idiomatic and safe way to do that?

What happens if you make coro a property and just start it multiple times?

Dunno? But are you interested in finding out? You could check the kdoc. It might solve your problem?

Ah, it will simply return false and not do anything if that coro was already started or completed. So not very useful here.

Isn't that what you want? Star a coro the first time startCoro is called and do nothing if it is already started?

but i want to _re-start_ it if it was completed

I see. Then I guess it does not get much simpler then what you have.

Just watch out for a coroutine leak. In the code above, you are always launching a new coroutine, leaving it dangling in the `NEW` state.

It's not launched, just created (lazy)... Doesn't it get GC'd?

But there isn't any reference to the Job, so it can't ever be launched, so the GC should collect it?

if you start it, there still is no ref and it would live until completed

maybe an `else coro.cancel()`  would help

How about this one?
```val coroRunning = AtomicBoolean(false)

/// Start my coroutine, may be called from any thread
fun startCoro () {
    // If coro is running, do nothing.
    if (coroRunning.compareAndExchange(false, true)) {
        coroutineScope.launch(<http://Dispatchers.IO|Dispatchers.IO>) {
            // Do the actual work here ...
            coroRunning.set(false)
        }
    }
}```

looks nice... Hmm, I think some requirements changed and I have to do the whole thing differently :man-facepalming: thanks anyways :smile: