Hi, I believe this is Kotlin related as I have an issue with coroutines. Recently I've joined a project where Project Reactor is used with some light use of Coroutines and both approaches use scheduler with this config:

Schedulers.fromExecutor(Executors.newFixedThreadPool(75))

My problem is that when I rewrote this:

@GetMapping("/get-stuff")
fun getStuff(
    @RequestParam param: String
): Mono<ResponseObject> = Mono.fromCallable {
    service.getStuff(param = param)
}.subscribeOn(blockingScheduler)

to use coroutines:

@GetMapping("/get-stuff")
suspend fun getStuff(
    @RequestParam param: String
): ResponseObject = withContext(blockingScheduler.asCoroutineDispatcher()) {
    service.getStuff(param = param)
}

the memory usage has increased almost 2-3 times. Do you have any idea why the performance might so much worse? That's something I definitely did not expect. Edit: I forgot to mention - the behaviour was the same when we tried to use

<http://Dispatchers.IO|Dispatchers.IO>

instead of the scheduler

I need to receive 4 different request bodies in the same endpoint, is there a simple way to do it?

Hello folks, I’m confused about something. So I’m using Spring Boot 3, when I create a

@Configuration

annotated class that defines some beans, is it necessary that I

@Import

it in the

@SpringBootApplication

annotated class? If I don’t do this the beans aren’t available in the application context, but if I do they are loaded. Examples I find online doesn’t do this it seems For example, I defined a configuration class that sets up various settings for OpenAPI, if I don’t

@Import

this class in the main application class my beans don’t get used, but if I do they get used, however examples I saw online doesn’t do this.

Take a look at this new way to guarding codebase consistency. I invite you to explore these Clean Architecture snippets together with Spring Snippets. I would greatly appreciate your insights (here or #konsist channel):

Is there a learning resource on how to architect spring boot microservices using Clean Architecture?

https://twitter.com/sdeleuze/status/1699733297801175043 https://mastodon.online/@sdeleuze/111023426795945933

I posted multichannel so i leave link only one post. https://kotlinlang.slack.com/archives/C4GKV43N2/p1694159243720809

how to use "kotlin exposed" in spring boot??

How to deal with native queries and dtos in kotlin?

I am using spring tools with the kotlin plugin but unable to run my spring project. I get the following error: Error: Could not find or load main class za.co.vsp.nbrmanagement.NbrmanagementApplication Caused by: java.lang.ClassNotFoundException: za.co.vsp.nbrmanagement.NbrmanagementApplication

Hey Spring devs - I need your help with fixing a bug in the open-source lib of mine - Konsist. The issue is this after adding a dependency (and not even using it) the

mvn clean package

command fails with error. Coming from Android I have never seen such behaviour (at least when dependency is not used) 🤔. Any Spring Ninja 🥷 could take a look and help me with fixing this or at least share more light to help understand why this happens? https://github.com/LemonAppDev/konsist/discussions/555

Hi I am trying to get security resource server working with Spring 3 and Kotlin and it’s proving difficult.

@Configuration
class SecurityConfig {

    @Bean
    fun securityFilterChain(http: HttpSecurity): SecurityFilterChain {
        http
            .csrf { obj: CsrfConfigurer<HttpSecurity> -> obj.disable() }
            .oauth2ResourceServer { oauth2: OAuth2ResourceServerConfigurer<HttpSecurity?> ->
                oauth2.jwt(
                    Customizer.withDefaults()
                )
            }
        return http.build()
    }
}

The error I am getting is

.   ____          _            __ _ _
 /\\ / ___'_ __ _ _(_)_ __  __ _ \ \ \ \
( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \
 \\/  ___)| |_)| | | | | || (_| |  ) ) ) )
  '  |____| .__|_| |_|_| |_\__, | / / / /
 =========|_|==============|___/=/_/_/_/
 :: Spring Boot ::                (v3.1.4)

2023-09-24T08:48:34.546-04:00  INFO 10957 --- [  restartedMain] com.freighthero.secu.SecuApplicationKt   : Starting SecuApplicationKt using Java 17.0.8.1 with PID 10957 (/Users/oadeojo/Development/kotlin/spring/secu/build/classes/kotlin/main started by oadeojo in /Users/oadeojo/Development/kotlin/spring/secu)
2023-09-24T08:48:34.547-04:00  INFO 10957 --- [  restartedMain] com.freighthero.secu.SecuApplicationKt   : No active profile set, falling back to 1 default profile: "default"
2023-09-24T08:48:34.574-04:00  INFO 10957 --- [  restartedMain] .e.DevToolsPropertyDefaultsPostProcessor : Devtools property defaults active! Set 'spring.devtools.add-properties' to 'false' to disable
2023-09-24T08:48:34.574-04:00  INFO 10957 --- [  restartedMain] .e.DevToolsPropertyDefaultsPostProcessor : For additional web related logging consider setting the 'logging.level.web' property to 'DEBUG'
2023-09-24T08:48:35.147-04:00  WARN 10957 --- [  restartedMain] onfigReactiveWebServerApplicationContext : Exception encountered during context initialization - cancelling refresh attempt: org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'securityFilterChain' defined in class path resource [com/freighthero/secu/SecurityConfig.class]: Unsatisfied dependency expressed through method 'securityFilterChain' parameter 0: No qualifying bean of type 'org.springframework.security.config.annotation.web.builders.HttpSecurity' available: expected at least 1 bean which qualifies as autowire candidate. Dependency annotations: {}
2023-09-24T08:48:35.155-04:00  INFO 10957 --- [  restartedMain] .s.b.a.l.ConditionEvaluationReportLogger : 

Error starting ApplicationContext. To display the condition evaluation report re-run your application with 'debug' enabled.
2023-09-24T08:48:35.164-04:00 ERROR 10957 --- [  restartedMain] o.s.b.d.LoggingFailureAnalysisReporter   : 

***************************
APPLICATION FAILED TO START
***************************

Description:

Parameter 0 of method securityFilterChain in com.freighthero.secu.SecurityConfig required a bean of type 'org.springframework.security.config.annotation.web.builders.HttpSecurity' that could not be found.


Action:

Consider defining a bean of type 'org.springframework.security.config.annotation.web.builders.HttpSecurity' in your configuration.


Process finished with exit code 0

This was the answer to my issue https://kotlinlang.slack.com/archives/C0B8ZTWE4/p1695583988659349?thread_ts=1695559834.135269&cid=C0B8ZTWE4

Hey guys. I have problem to set custom exceptions handlers for Spring with suspend controller. Controller Advice is not working as for sync. It's working for Mono but not suspend. It should not be the same? Maybe you can find any example? SpringBoot 3.1.+ Kotlin 1.9.+

Hello! I wanna write (spring) kafka producers generator. Our services use a lot of this stuff and I feel it dumb to copy-paste the same beans million times. but I can't invent the flawless solution((( my last idea was to write in config pairs "topic to className". but what to do if one dto should be sent to one of multiple possible topics (multiple topics accept the same dto but some logic defines which one to choose)?.. have somebody seen some idea description (article or post or anything else)?

I’m having an issue with spring boot and serialization with kotlinx-datetime. for an Instant it will use the correct KSerializer class and deserialize “2023-09-30T172106.219Z”, however when it goes to serialize the Instant it outputs

{
  "epochSeconds": 1696094517,
  "value$kotlinx_datetime": "2023-09-30T17:21:57Z",
  "nanosecondsOfSecond": 0
}

any ideas as to why it wouldn’t be using the correct serializer? I think it’s switching back to jackson for serialization

Is there any progress being made on supporting KSP instead of kapt in the spring boot configuration processor?

when using spring webflux and kotlin coroutines, I would like to add a header value to MDC. We already have a standard webfilter that adds the header value from the request to the reactor context. Now I want my app to read that value from the reactor-context and then put it on the MDC. I created my own WebFilter and using Mono.deferContextual I am able to get the value, like this:

override fun filter(exchange: ServerWebExchange, chain: WebFilterChain): Mono<Void> {
        return Mono.deferContextual {
            if (it.hasKey(MYID)) {
                MDC.putCloseable(MYID, it.get(MYID))
            }
            chain.filter(exchange)
        }
    }

The @RestControntroller functions are all suspended, and we are running netty (so full webflux). In the

async

code I have also added the MDCContext(), to make sure the MDC values are passed in. Is this a good solution? Are there any other pitfalls I need to be aware of? Or does anyone have a better implementation for this scenario

@sdeleuze do you have a version of https://github.com/sdeleuze/spring-jvm-aot that also compares spring-fu-like usage on JIT? like no autoconfiguration enabled and using beans and routing dsls?

If you missed it, not specific to Kotlin but likely of interest as well for most Kotlin + Spring server-side developers: https://twitter.com/springcentral/status/1713930043112464813 https://mastodon.online/@sdeleuze/111245268358362189

Hello, I have question about Schedulers and coroutines together in Spring application. I am basically having this code which defines scheduled method, with always throwing RuntimeException (for testing purposes)

private val coroutineScope = CoroutineScope(Dispatchers.Unconfined)

private val logger: Logger = LoggerFactory.getLogger("BirthdayCongratulationScheduler::class.java")

/**
 * Set up cron which starts every 10 seconds
 */
@Scheduled(cron = CRON_SCHEDULE)
@SchedulerLock(name = CRON_NAME)
fun congratulate() {
    val handler = CoroutineExceptionHandler { _, exception ->
        logger.error("CoroutineExceptionHandler got $exception")
    }
    runCatching {
        logger.info("CRON $CRON_NAME has started.")
        coroutineScope.launch(handler) {
            throw RuntimeException("Not implemented")
        }
    }.onFailure { throwable ->
        logger.error("CRON $CRON_NAME has failed. Check the error message: ${throwable.message}.")
    }.onSuccess {
        logger.info("CRON $CRON_NAME has finished.")
    }
}

companion object {
    private const val CRON_NAME = "myScheduler"
    private const val CRON_SCHEDULE = "*/10 * * * * *"
}

and this is print log from console:

Started ApiApplicationKt in 8.411 seconds (process running for 8.76)
2023-10-20T10:22:10.103+02:00  INFO 82566 --- [   scheduling-1] .h.e.s.s.BirthdayCongratulationScheduler : CRON birthdayScheduler has started.
2023-10-20T10:22:10.106+02:00 ERROR 82566 --- [   scheduling-1] .h.e.s.s.BirthdayCongratulationScheduler : CoroutineExceptionHandler got java.lang.RuntimeException: Not implemented
2023-10-20T10:22:10.106+02:00  INFO 82566 --- [   scheduling-1] .h.e.s.s.BirthdayCongratulationScheduler : CRON birthdayScheduler has finished.
2023-10-20T10:22:20.032+02:00  INFO 82566 --- [   scheduling-1] .h.e.s.s.BirthdayCongratulationScheduler : CRON birthdayScheduler has started.
2023-10-20T10:22:20.034+02:00  INFO 82566 --- [   scheduling-1] .h.e.s.s.BirthdayCongratulationScheduler : CRON birthdayScheduler has finished.
2023-10-20T10:22:30.033+02:00  INFO 82566 --- [   scheduling-1] .h.e.s.s.BirthdayCongratulationScheduler : CRON birthdayScheduler has started.
2023-10-20T10:22:30.033+02:00  INFO 82566 --- [   scheduling-1] .h.e.s.s.BirthdayCongratulationScheduler : CRON birthdayScheduler has finished.
repeating infinitely...

I am really confused, why

CoroutineExceptionHandler

is catching the exception only one time. And after that the cron is still running without calling the logic in

runCatching{}

as you can see in print in console? Can someone explain it to me? Or just provide link where I can read about this? Is this approach even correct? Or what is the best practise to call suspend functions in body of Scheduled method? thanks, Dusan

I have only found documentation how to use Jackson to create a PATCH endpoint in spring boot using json-patch (https://github.com/java-json-tools/json-patch) I am using kotlinx-serialization. Any information on this?

Hi! is there a channel about interactions with reactive libs? my question is: does it worth to combine spring, kotlin coroutines and r2dbc? I see it as kotlin with r2dbc combinations is super fragile and produces a lot of errors. I solve them one by one but don't know how long it will last. so does it worth to solve em all (and utilize an unpredictable amount of time)? on the other hand i can stand with coroutines and jdbc

I need to secure an API with API Keys. I’m looking for a finished solution that does the following: 1. Can automatically create an API key when a user creates a paid subscription in Stripe 2. Tracks usage of this API key so the user doesn’t go above quota 3. Implements global rate-limits per api key I have found moesif.com but its a bit pricy, I can run some own infrastructure if it means lower cost. Does anyone know of a tool like this?

would it be reasonable to contribute an extension function i wrote

inline fun <reified T : Any> PropertyResolver.getProperty(key: String, default: T): T {
    return getProperty(key, T::class.java, default)
}

upstream to spring? (can anyone on the spring team here give me some guidance on that?)

how to use

firebase-admin

in

SpringBoot

to build GraalVM native image

I m planning to migrate from ktor to spring boot , I am simply unable to figure out how to get ktor running on Google app engine properly and there seems to be a lack of community support for ktor, a simple rest api. Whats your take on kotlin's 1st class support on spring boot and support for coroutines

I want to ask about the future: should I continue using

Java

with

Spring

, or will Spring use

Kotlin

more frequently in the future?