Is there a difference between ``` launch(newSingleThreadContext("ServiceContext")) { ... } ``` and...

# coroutines

[Dennis Schröder]

Is there a difference between

launch(newSingleThreadContext("ServiceContext")) {
 ...
}

and

launch {
 withContext((newSingleThreadContext("ServiceContext") {
    ....  
  }
}

?

[Marko Mitic]

Option #2 might do more work/thread switching, depending on CoroutineScope you're launching from

[Dennis Schröder]

Yes and as far as I know the later is obsolet

[bdawg.io]

Since you're creating a new thread context, #2 does indeed do an extra context switch which just causes extra overhead before your real work actually begins

[bdawg.io]

That might not necessarily be the case if you did this though

launch(start = UNDISPATCHED) { 
    withContext(newSingleThreadContext(...)) { 
        doSomething() 
    } 
}

[elizarov]

There is no difference, but extra work and extra code in the second case. Use the first way when you need to launch in a specific context. Note, that that newSingleThreadContex is a resource that must be closed. Both your code example leak the newly created thread every time they launch a coroutine. Don’t do this. Do this:

// at top level in some file
val myContext = newSingleThreadContex(...)

// somewhere in code
launch(myContext) { ... }

[bdawg.io]

Is this thread context Closable that that it could be used via newSingleThreadContext(...).use { launch(it) { ... } } where it makes sense?

[elizarov]

Yes