Fork with loop causing stack overflow

[hschreeck]

Hi everyone,

I am currently trying to create a (more or less) simple approval workflow with a timeout. Like in this example (https://elsa-workflows.github.io/elsa-core/docs/next/guides/guides-document-approval) I am using a fork activity to split the workflow. However, for my use case I need to loop back to the fork activity (depending on the outcome of the approval activity). Unfortunately, this leads to a stack overflow and a crash.

While I was trying to find the problem I created a minimalistic version of the workflow:

builder
                .WithDisplayName("My workflow")
                .Then<Fork>(
                    fork => fork.WithBranches("ApprovalBranch", "TimeOutBranch"),
                    fork =>
                    {
                        var approvalBranch = fork
                            .When("ApprovalBranch")
                            .Timer(Duration.FromSeconds(10))
                            .Then(x => { Console.WriteLine("Timeout 1 done!"); })
                            .ThenNamed("Join")
                            ;

                        var timeOutBranch = fork
                            .When("TimeoutBranch")
                            .Timer(Duration.FromSeconds(150))
                            .Then(x => { Console.WriteLine("Timeout 2 done!"); })
                            .ThenNamed("Join")
                            ;
                    }
                )
                .WithName("Fork")
                .Add<Join>(join => join.WithMode(Join.JoinMode.WaitAny)).WithName("Join")
                .IfTrue(x => true, x => x.ThenNamed("Fork"))
                ;

So here I am not using my custom activities but only two timers. The workflows starts as I would expect but as soon as the first timer is done and the IfTrue() part is reached the programm crashes with this error:

Stack overflow.
   at System.MulticastDelegate.CtorClosed(System.Object, IntPtr)
   at Elsa.WorkflowExecutionContextExtensions.GetInboundConnections(Elsa.Services.Models.WorkflowExecutionContext, System.String)
   at Elsa.WorkflowExecutionContextExtensions+<GetInboundActivityPathInternal>d__5.MoveNext()
   at System.Linq.Enumerable+DistinctIterator`1[[System.__Canon, System.Private.CoreLib, Version=5.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e]].MoveNext()
   at Elsa.WorkflowExecutionContextExtensions+<GetInboundActivityPathInternal>d__5.MoveNext()
   at System.Linq.Enumerable+DistinctIterator`1[[System.__Canon, System.Private.CoreLib, Version=5.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e]].MoveNext()
   at Elsa.WorkflowExecutionContextExtensions+<GetInboundActivityPathInternal>d__5.MoveNext()
   at System.Linq.Enumerable+DistinctIterator`1[[System.__Canon, System.Private.CoreLib, Version=5.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e]].MoveNext()
   at Elsa.WorkflowExecutionContextExtensions+<GetInboundActivityPathInternal>d__5.MoveNext()
   at System.Linq.Enumerable+DistinctIterator`1[[System.__Canon, System.Private.CoreLib, Version=5.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e]].MoveNext()
   at Elsa.WorkflowExecutionContextExtensions+<GetInboundActivityPathInternal>d__5.MoveNext()
   at System.Linq.Enumerable+DistinctIterator`1[[System.__Canon, System.Private.CoreLib, Version=5.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e]].MoveNext()
   at Elsa.WorkflowExecutionContextExtensions+<GetInboundActivityPathInternal>d__5.MoveNext()
   at System.Linq.Enumerable+DistinctIterator`1[[System.__Canon, System.Private.CoreLib, Version=5.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e]].MoveNext()

The stack trace is even longer of course, this is just the beginning.

My question is: Am I doing something wrong here? Is there another way to achieve my goal?

cheers,
Harrison

[sfmskywalker]

This looks like a bug to me. Would you mind creating an issue for it referencing this topic?

[hschreeck]

Thanks for the quick answer!
What do you mean with "animatie"? I'm afraid I don't know what that is.

[sfmskywalker]

Sorry, i was too quick to notice the spelling correction error ;)

[sfmskywalker]

I meant to say: “an issue” - updated my reply.

[hschreeck]

From the context I actually assumed this, but I wanted to be sure ;) I will create the issue.