B4J Question How to use resumable subs to prevent blocking the thread when many subs are stringed

Sub S2
    'do something
    wait for S3(param)
End Sub

Sub S3(param as map)
    'S3 requires some time to process and will block the thread.

   sleep 
   sleep
   sleep

End Sub

Sub S1
    'update UI
    wait fo (S2) Complete (result as Object)
    'update UI
End Sub

Sub S2 as ResumableSub
    'do something
    wait for (S3(param)) Complete (result as Object)
    return value
End Sub

Sub S3(param as map) as ResumableSub
    'S3 requires some time to process and will block the thread.
    return  value
End Sub

Sub A1
   
    Log("A1 Start")
   
    A2

    Log("A1 End")
   
End Sub

Sub A2

    Log("A2 Start")
   
    A3
   
    Log("A2 End")

End Sub

Sub A3()

    Log("A3 Start")

    Log("start time: " & DateTime.Time(DateTime.Now))
    Dim x As Long
    For x = 1 To 100000000
        If x Mod 1000 = 0 Then Sleep(0) 'try different values
    Next
    Log("end time: " & DateTime.Time(DateTime.Now))
   
    Log("A3 End")

End Sub

Waiting for debugger to connect...
Program started.
A1 Start
A2 Start
A3 Start
start time: 15:59:06
end time: 15:59:17
A3 End
A2 End
A1 End

Sub A1
    Log("A1 Start")
    wait for (A2) complete (result As Object)
    Log("A1 End")
End Sub

Sub A2 As ResumableSub
    Log("A2 Start")  
    wait for (A3) complete (result As Object)  
    Log("A2 End")
End Sub

Sub A3() As ResumableSub
    Log("A3 Start")
    Log("start time: " & DateTime.Time(DateTime.Now))
    Dim x As Long
    For x = 1 To 100000000
        If x Mod 1000 = 0 Then Sleep(0) 'try different values
    Next
    Log("end time: " & DateTime.Time(DateTime.Now))  
    Log("A3 End")
End Sub