I've been holding off from coroutines a while now....

# coroutines

[Byron Katz]

I've been holding off from coroutines a while now. Every time I tried adding them, I'd run into severe headwinds. Today I tried again, and basically just converted my executor service like this:

-    executorService: ExecutorService = Executors.newCachedThreadPool(Executors.defaultThreadFactory())
+    executorService: ExecutorService = Executors.newCachedThreadPool(Executors.defaultThreadFactory()).asCoroutineDispatcher().executor as ExecutorService,

and bam! Performance up by 40% on my heaviest function.

[elizarov]

Very strange. It should not be making a difference. Double-check your benchmarks.

[Byron Katz]

The man himself! But why shouldn't that make a difference?

[elizarov]

val originalExecutor = Executors.newCachedThreadPool(Executors.defaultThreadFactory())
val resultingExecutor = originalExecutor.asCoroutineDispatcher().executor as ExecutorService
println(resultingExecutor === originalExecutor) // prints true

[Byron Katz]

aww

[Byron Katz]

I should have looked closer. So, what is the proper way to convert an executor service to a coroutine version?

[elizarov]

It is the proper way. What are you trying to achieve?

[Byron Katz]

Trying to use the exact same interface that ExecutorService provides for threads, but for coroutines, i.e. foo.submit ()

[elizarov]

For what?

[Byron Katz]

for a non-ssl server, an ssl-server, a blockingLinkedQueue, and for handling client requests. I pass one ExecutorService around the entire application to be used. Currently it works fine with a cached pool of threads but I was hoping to just sprinkle some magic coroutines in to avoid the 1-1 dependency on OS threads.

[elizarov]

It does not work this way. There is no magic

[Byron Katz]

😢

[Byron Katz]

https://github.com/7ep/r3z/blob/f8d62af7a0538f7f07b8e03d657cbc33782416f5/src/main/kotlin/coverosR3z/Main.kt#L23

[Byron Katz]

I guess I was hoping there was a way to incorporate coroutines without a total overhaul of the codebase, and to date I haven't found a way to do this.