Does spring boot perhaps impose a particular versi...

# spring

[epchris]

Does spring boot perhaps impose a particular version of kotlin or coroutines?

[sdeleuze]

Prior Boot 2.2, no support for Coroutines, so no version requirement. In Boot 2.2 Coroutines 1.3+ only as specified in the refdoc.

[sdeleuze]

Also Coroutines are only supported in WebFlux not MVC.

[epchris]

We’re not using webflux I don’t believe, but we are using spring boot 2.1.6. So that’ll be an issue right, like I can’t even manually indicate coroutines as a dependency and have it work?

[sdeleuze]

I guess it depends what you mean by "have it work"

[sdeleuze]

You can call runBlocking inside regular handler methods but that's not something I would recommend.

[sdeleuze]

suspend fun handler methods are only supported in WebFlux as of Spring Framework 5.2.

[epchris]

well, have that call to GlobalScope.launch

[epchris]

sorry, that’s what the line of code in question is doing

[epchris]

I can’t say I know enough about Spring to know why it would effect coroutines, I’m a little new to the whole thing

[epchris]

I assumed I could just declare a dependency on kotlinx.coroutines and then the documented stuff would “just work”

[epchris]

but my GlobalScope.launch line causes that stack trace to pop up

[sdeleuze]

Your stacktrace is likely because of a mismatch between Kotlin and Coroutines version

[sdeleuze]

We manage that in Boot 2.2+ not before

[sdeleuze]

So you have to find the right combo

[sdeleuze]

Kotlin 1.3.50 + Coroutines 1.3.x works well together for example

[epchris]

ok, I have kotlin 1.3.20 and coroutines 1.1.1

[epchris]

I thought that was documented combination

[epchris]

unless Spring boot is “magically” pulling in a different version of kotlin at runtime

[epchris]

I just changed my coroutines version:
implementation "org.jetbrains.kotlinx:kotlinx-coroutines-core:1.3.1"
and am still getting the same thing 😞

[sdeleuze]

What version of Kotlin are you using? Have you double check the version of each Kotlin and Coroutines dependencies ? (version mix happens pretty quickly without dependency management)

[epchris]

implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk8:1.3.20"
  implementation "org.jetbrains.kotlin:kotlin-reflect:1.3.20"

[sdeleuze]

Have you read what I wrote ?

[sdeleuze]

Kotlin 1.3.50 + Coroutines 1.3.x works well together for example

[epchris]

I’ll give that a try, apologies. I’m a little new to all of these dependencies

[epchris]

a maybe-gradle-related question: I’m working in a subproject that pulls in spring boot and kotlin and coroutines (this is where I’ve updated the dependency versions). The top-level project declares none of these as direct dependencies. Is there a chance that the subproject is being compiled with those versions, but then the app is being packaged up with a different version for some reason?

[epchris]

(after updating to kotlin 1.3.50, I still get the same error)

[sdeleuze]

./gradlew dependencies

[sdeleuze]

Also use same version between plugin and dependencies

[epchris]

org.jetbrains.kotlin:kotlin-stdlib-jdk8:1.3.50 -> 1.2.71 does that output mean that it picked version 1.2.71?

[sdeleuze]

In any case since you are using a version of Spring that does not support Coroutines I think your question will be a better fit in #coroutines or #gradle.

Side note : if you are very new to that, I am not sure using Coroutines in a version of Boot that provides no support for it is a good idea. I would limit that kind of thing to developers that have a significant experience of Coroutines.

[epchris]

Thanks, I appreciate the help

[sdeleuze]

Yes I think 1.2.71 is used hence your error, that's why we provide Coroutines version management in Boot 2.2

[sdeleuze]

To be sure to avoid this kind of issue

[epchris]

this is probably a very complicated question, but would you anticipate any “problems” arising from upgrading from spring-boot 2.1.6 to 2.2?

[sdeleuze]

We do our best to avoid such issue, not saying you won't have but if you are using Kotlin + Coroutines, Boot 2.2 is highly recommanded given all the imrpovements we did.

[sdeleuze]

And 2.2.0.M6 is now available

[sdeleuze]

Last milestone before RC1 so pretty stable

[epchris]

Would you say it’s ready for production use?

[sdeleuze]

Of course not

[sdeleuze]

But GA will be here in October

[epchris]

🙂 awesome

[epchris]

we’ll upgrade then I suppose

[epchris]

Thanks again for all your help