Why would Quarkus/Smalrye messaging consumer nack on on blocked vertx thread?

Question

I though this message was for warning, so why would the consumer nack it? Also adding @Blocking to the process function below seems to "fix" the issue.

I have my processor like so...

@Incoming("topic-in")
public void process(String event) {
    // This call Http rest Clients underneath 
    someService.update(event);
}

java.lang.IllegalStateException: The current thread cannot be blocked: vert.x-eventloop-thread-0
    at io.smallrye.mutiny.operators.uni.UniBlockingAwait.await(UniBlockingAwait.java:30)
    at io.smallrye.mutiny.groups.UniAwait.atMost(UniAwait.java:65)
    at io.smallrye.mutiny.groups.UniAwait.indefinitely(UniAwait.java:46)
    at io.quarkus.cache.runtime.CacheResultInterceptor.intercept(CacheResultInterceptor.java:116)
    at io.quarkus.cache.runtime.CacheResultInterceptor_Bean.intercept(Unknown Source)
    at io.quarkus.arc.impl.InterceptorInvocation.invoke(InterceptorInvocation.java:41)
    at io.quarkus.arc.impl.AroundInvokeInvocationContext.perform(AroundInvokeInvocationContext.java:41)
    at io.quarkus.arc.impl.InvocationContexts.performAroundInvoke(InvocationContexts.java:32)
    at xxxxxx.service.AuthService_Subclass.authenticate(Unknown Source)
    at xxxxxx.service.SomeService.update(SubscriberService.java:46)
    at xxxxxx.service.SomeService_Subclass.update$$superforward1(Unknown Source)
    at xxxxxx.service.SomeService_Subclass$$function$$3.apply(Unknown Source)
    at io.quarkus.arc.impl.AroundInvokeInvocationContext.proceed(AroundInvokeInvocationContext.java:54)
    at io.smallrye.faulttolerance.FaultToleranceInterceptor.lambda$syncFlow$3(FaultToleranceInterceptor.java:253)
    at io.smallrye.faulttolerance.core.InvocationContext.call(InvocationContext.java:20)
    at io.smallrye.faulttolerance.core.Invocation.apply(Invocation.java:29)
    at io.smallrye.faulttolerance.core.retry.Retry.doApply(Retry.java:88)
    at io.smallrye.faulttolerance.core.retry.Retry.apply(Retry.java:42)
    at io.smallrye.faulttolerance.FaultToleranceInterceptor.syncFlow(FaultToleranceInterceptor.java:255)
    at io.smallrye.faulttolerance.FaultToleranceInterceptor.intercept(FaultToleranceInterceptor.java:182)
    at io.smallrye.faulttolerance.FaultToleranceInterceptor_Bean.intercept(Unknown Source)
    at io.quarkus.arc.impl.InterceptorInvocation.invoke(InterceptorInvocation.java:41)
    at io.quarkus.arc.impl.AroundInvokeInvocationContext.perform(AroundInvokeInvocationContext.java:41)
    at io.quarkus.arc.impl.InvocationContexts.performAroundInvoke(InvocationContexts.java:32)
    at xxxxxx.service.SubscriberService_Subclass.update(Unknown Source)
    at xxxxxx.messaging.MyProcessor.updateCustomer(CustomerProcessor.java:6262)
    at xxxxxx.messaging.MyProcessor.update(CustomerProcessor.java:6204)
    at xxxxxx.messaging.MyProcessor.process(CustomerProcessor.java:6162)
    at xxxxxx.messaging.MyProcessor_ClientProxy.process(Unknown Source)
    at xxxxxx.messaging.MyProcessor_SmallRyeMessagingInvoker_process_bd386abe989418e778612ad8212523c81d813d5e.invoke(Unknown Source)
    at io.smallrye.reactive.messaging.providers.AbstractMediator.invoke(AbstractMediator.java:95)
    at io.smallrye.reactive.messaging.providers.AbstractMediator.lambda$invokeOnMessageContext$1(AbstractMediator.java:103)
    at io.smallrye.reactive.messaging.providers.locals.LocalContextMetadata.lambda$invokeOnMessageContext$0(LocalContextMetadata.java:34)
    at io.smallrye.reactive.messaging.providers.locals.LocalContextMetadata.lambda$invokeOnMessageContext$2(LocalContextMetadata.java:55)
    at io.smallrye.context.impl.wrappers.SlowContextualConsumer.accept(SlowContextualConsumer.java:21)
    at io.smallrye.mutiny.operators.uni.builders.UniCreateWithEmitter.subscribe(UniCreateWithEmitter.java:22)
    at io.smallrye.mutiny.operators.AbstractUni.subscribe(AbstractUni.java:36)
    at io.smallrye.mutiny.operators.uni.UniOnItemOrFailureFlatMap.subscribe(UniOnItemOrFailureFlatMap.java:27)
    at io.smallrye.mutiny.operators.AbstractUni.subscribe(AbstractUni.java:36)
    at io.smallrye.mutiny.converters.uni.UniToMultiPublisher$UniToMultiSubscription.request(UniToMultiPublisher.java:74)
    at io.smallrye.mutiny.operators.multi.MultiFlatMapOp$FlatMapInner.onSubscribe(MultiFlatMapOp.java:601)
    at io.smallrye.mutiny.converters.uni.UniToMultiPublisher.subscribe(UniToMultiPublisher.java:26)
    at io.smallrye.mutiny.groups.MultiCreate$1.subscribe(MultiCreate.java:163)
    at io.smallrye.mutiny.operators.multi.MultiFlatMapOp$FlatMapMainSubscriber.onItem(MultiFlatMapOp.java:193)
    at io.smallrye.mutiny.operators.multi.MultiMapOp$MapProcessor.onItem(MultiMapOp.java:50)
    at io.smallrye.mutiny.subscription.MultiSubscriber.onNext(MultiSubscriber.java:61)
    at io.smallrye.mutiny.subscription.SafeSubscriber.onNext(SafeSubscriber.java:99)
    at io.smallrye.mutiny.helpers.HalfSerializer.onNext(HalfSerializer.java:31)
    at io.smallrye.mutiny.helpers.StrictMultiSubscriber.onItem(StrictMultiSubscriber.java:85)
    at io.smallrye.mutiny.operators.multi.MultiOperatorProcessor.onItem(MultiOperatorProcessor.java:100)
    at io.smallrye.reactive.messaging.providers.locals.ContextDecorator$ContextMulti$ContextProcessor.lambda$onItem$1(ContextDecorator.java:78)
    at io.vertx.core.impl.AbstractContext.dispatch(AbstractContext.java:100)
    at io.vertx.core.impl.AbstractContext.dispatch(AbstractContext.java:63)
    at io.vertx.core.impl.EventLoopContext.lambda$runOnContext$0(EventLoopContext.java:38)
    at io.netty.util.concurrent.AbstractEventExecutor.safeExecute(AbstractEventExecutor.java:164)
    at io.netty.util.concurrent.SingleThreadEventExecutor.runAllTasks(SingleThreadEventExecutor.java:469)
    at io.netty.channel.nio.NioEventLoop.run(NioEventLoop.java:503)
    at io.netty.util.concurrent.SingleThreadEventExecutor$4.run(SingleThreadEventExecutor.java:986)
    at io.netty.util.internal.ThreadExecutorMap$2.run(ThreadExecutorMap.java:74)
    at io.netty.util.concurrent.FastThreadLocalRunnable.run(FastThreadLocalRunnable.java:30)
    at java.base/java.lang.Thread.run(Thread.java:829)

Answer 1

@Blocking seems to fix in your case because it indicates to quarkus that this operation is blocking, it makes quarkus happy. But when you don't put it, and still do a blocking operation, quarkus complains.

I believe your http rest endpoint call is not reactive, that's why quarkus complains. Try replacing it by any reactive operation and try again.

If it's working, your solution simply is to use reactive http client to make your calls.

Check quarkus http reactive rest client documentation