```// assuming this is a singleton private val def...

# coroutines

[cdurham]

// assuming this is a singleton
private val deferredThing: Deferred<Thing> =
      ioScope.async(start = CoroutineStart.LAZY) {
        createThing()
      }

Are there guarantees that this block will only run a single time, no matter how many times it’s awaited / which threads call await?

[Youssef Shoaib [MOD]]

Yes!

[Dmitry Khalanskiy [JB]]

Another option to consider is

private val deferredThing: Deferred<Thing> by lazy {
  ioScope.async {
    createThing()
  }
}

This way, if deferredThing is never used, ioScope won't even learn about its existence, + it's using the more general mechanism, applicable in more contexts.

[cdurham]

yeah actually i was doing that initially but was thinking that synchronization by lazy and coroutines would be some sort of anti-pattern (I guess not 🤷 )

FWIW — this thing is always going to get used

[Youssef Shoaib [MOD]]

If it's always gonna get used, why not just launch it immediately? no need for lazy or LAZY then

[cdurham]

it’s an android app and i want to spread out the work instead of jamming up application start (re dagger init)