Reactor Core Issue Creating State Machine

[states87]

Hello, I upgraded my state machine to 4.0.0 and spring 3.2.0 with java 17, when creating the state machine I am getting this errors:

2023-12-27T15:05:22.802+01:00 INFO 90303 --- [demo] [nio-8084-exec-1] o.s.s.s.DefaultStateMachineService : Acquiring machine with id edjsd9d9d43uu400
2023-12-27T15:05:22.802+01:00 INFO 90303 --- [demo] [nio-8084-exec-1] o.s.s.s.DefaultStateMachineService : Getting new machine from factory with id edjsd9d9d43uu400
2023-12-27T15:05:23.440+01:00 ERROR 90303 --- [demo] [ parallel-8] reactor.core.publisher.Operators : Operator called default onErrorDropped

reactor.core.Exceptions$ErrorCallbackNotImplemented: reactor.core.Exceptions$RetryExhaustedException: Retries exhausted: 10/10
Caused by: reactor.core.Exceptions$RetryExhaustedException: Retries exhausted: 10/10
at reactor.core.Exceptions.retryExhausted(Exceptions.java:306)
at reactor.util.retry.RetryBackoffSpec.lambda$static$0(RetryBackoffSpec.java:68)
at reactor.util.retry.RetryBackoffSpec.lambda$null$4(RetryBackoffSpec.java:560)
at reactor.core.publisher.FluxConcatMapNoPrefetch$FluxConcatMapNoPrefetchSubscriber.onNext(FluxConcatMapNoPrefetch.java:183)
at reactor.core.publisher.FluxContextWrite$ContextWriteSubscriber.onNext(FluxContextWrite.java:107)
at reactor.core.publisher.SinkManyEmitterProcessor.drain(SinkManyEmitterProcessor.java:471)
at reactor.core.publisher.SinkManyEmitterProcessor$EmitterInner.drainParent(SinkManyEmitterProcessor.java:615)
at reactor.core.publisher.FluxPublish$PubSubInner.request(FluxPublish.java:873)
at reactor.core.publisher.FluxContextWrite$ContextWriteSubscriber.request(FluxContextWrite.java:136)
at reactor.core.publisher.FluxConcatMapNoPrefetch$FluxConcatMapNoPrefetchSubscriber.innerComplete(FluxConcatMapNoPrefetch.java:274)
at reactor.core.publisher.FluxConcatMap$ConcatMapInner.onComplete(FluxConcatMap.java:887)
at reactor.core.publisher.FluxContextWrite$ContextWriteSubscriber.onComplete(FluxContextWrite.java:126)
at reactor.core.publisher.MonoFlatMap$FlatMapMain.secondComplete(MonoFlatMap.java:246)
at reactor.core.publisher.MonoFlatMap$FlatMapInner.onNext(MonoFlatMap.java:305)
at reactor.core.publisher.MonoIgnoreThen$ThenIgnoreMain.complete(MonoIgnoreThen.java:292)
at reactor.core.publisher.MonoIgnoreThen$ThenIgnoreMain.onNext(MonoIgnoreThen.java:187)
at reactor.core.publisher.MonoIgnoreThen$ThenIgnoreMain.subscribeNext(MonoIgnoreThen.java:236)
at reactor.core.publisher.MonoIgnoreThen.subscribe(MonoIgnoreThen.java:51)
at reactor.core.publisher.MonoFlatMap$FlatMapMain.onNext(MonoFlatMap.java:165)
at reactor.core.publisher.MonoIgnoreThen$ThenIgnoreMain.complete(MonoIgnoreThen.java:292)
at reactor.core.publisher.MonoIgnoreThen$ThenIgnoreMain.onNext(MonoIgnoreThen.java:187)
at reactor.core.publisher.MonoDelay$MonoDelayRunnable.propagateDelay(MonoDelay.java:271)
at reactor.core.publisher.MonoDelay$MonoDelayRunnable.run(MonoDelay.java:286)
at reactor.core.scheduler.SchedulerTask.call(SchedulerTask.java:68)
at reactor.core.scheduler.SchedulerTask.call(SchedulerTask.java:28)
at java.base/java.util.concurrent.FutureTask.run$$$capture(FutureTask.java:264)
at java.base/java.util.concurrent.FutureTask.run(FutureTask.java)
at java.base/java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:304)
at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1136)
at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:635)
at java.base/java.lang.Thread.run(Thread.java:840)
Caused by: reactor.core.publisher.Sinks$EmissionException: Spec. Rule 1.3 - onSubscribe, onNext, onError and onComplete signaled to a Subscriber MUST be signaled serially.

The issue is fired at stateMachine.startReactively().block(); in the method handleStart. How to solve this issue? Thank you a loot.

[jvalkeal]

I think I've seen this before, possibly with tests so it may be race conditions. Need to investigate.