starting timer during prestart seems to sometimes cause an "ActorInitializationException: Exception during creation"

[brah-mcdude]

Cause: [akka://test/user/b#653027469]: Akka.Actor.ActorInitializationException: Exception during creation
 ---> System.InvalidOperationException: Worker in invalid state: 1
   at Akka.Actor.HashedWheelTimerScheduler.Start()
   at Akka.Actor.HashedWheelTimerScheduler.InternalSchedule(TimeSpan delay, TimeSpan interval, IRunnable action, ICancelable cancelable)
   at Akka.Actor.HashedWheelTimerScheduler.InternalScheduleTellOnce(TimeSpan delay, ICanTell receiver, Object message, IActorRef sender, ICancelable cancelable)
   at Akka.Actor.SchedulerBase.Akka.Actor.ITellScheduler.ScheduleTellOnce(TimeSpan delay, ICanTell receiver, Object message, IActorRef sender, ICancelable cancelable)
   at Akka.Actor.SchedulerExtensions.ScheduleTellOnceCancelable(IScheduler scheduler, TimeSpan delay, ICanTell receiver, Object message, IActorRef sender)
   at Akka.Actor.Scheduler.TimerScheduler.StartTimer(Object key, Object msg, TimeSpan timeout, TimeSpan initialDelay, Boolean repeat)
   at Akka.Actor.Scheduler.TimerScheduler.StartSingleTimer(Object key, Object msg, TimeSpan timeout)

Version Information
Version of Akka.NET?
1.5.13
Which Akka.NET Modules?
Akka.Actor.Scheduler.TimerScheduler
Akka.Actor.HashedWheelTimerScheduler

Describe the bug
I am running my tests. I am using the "Run Until Failure" menu item in the test explorer menu.
The tests always fail. Usually only after a few iterations (at around 70 iterations).

Last test log:
Test run finished: 119 Tests (118 Passed, 1 Failed, 0 Skipped) run in 15.9 min. Finished at iteration 127

To Reproduce
Steps to reproduce the behavior:
In my app, many things happen, but the essence of the bug (i did not write a separate test for this - so take it as an unproved theory):

1. create actor and start timer in prestart
2. "Run Until Failure" menu item in the test explorer menu
3. See error after many iterations

Expected behavior
I expect this exception to NOT happen. And for the tests iterations to continue.

Actual behavior
Test stops after a few iterations.

Environment
running on Windows.
Which version of .NET?
"Welcome to .NET 7.0!
SDK Version: 7.0.403"

[Aaronontheweb]

@brah-mcdude can you provide some actor code that we can look at in order to help reproduce?

[Aaronontheweb]

Just for clarification: this bug affects actors who use IWithTimers and call the StartTimer method inside the actor's PreStart override

[Aaronontheweb]

I tried to reproduce this @brah-mcdude

async Task Main()
{
	// Initialize Actor System
	var system = ActorSystem.Create("MySystem");

	// Create Props for the EchoActor
	var props = Props.Create<EchoActor>();

	// Create the EchoActor
	var echoActor = system.ActorOf(props, "echoActor");

	// Send 10 messages to the EchoActor
	for (int i = 0; i < 10; i++)
	{
		echoActor.Tell($"Message {i + 1}");
	}

	// Allow some time for messages to process before shutting down
	await system.WhenTerminated;
}

// Define the EchoActor class
public class EchoActor : ReceiveActor, IWithTimers
{
	private readonly ILoggingAdapter _log = Context.GetLogger();
	private int _msgCount = 0;
	public ITimerScheduler Timers { get; set; }

	public EchoActor()
	{
		NormalBehavior();
	}

	private void NormalBehavior()
	{
		ReceiveAny(message =>
		{
			_log.Info("Hit {0}", _msgCount++);
			if(_msgCount >= 10){
				Context.System.Terminate();
			}
		});
	}

	private class RecoverMarker { }

	protected override void PreRestart(Exception ex, object message)
	{
		Timers.StartPeriodicTimer("foo", "bar", TimeSpan.FromMilliseconds(100));
	}

}

Worked normally - what's the issue?

[Aaronontheweb]

BTW, this issue was actually #7174 and was resolved as part of Akka.NET v1.5.20.