What happens when an event is Broadcast from not the game thread?

[Mattlauk]

I have

DECLARE_EVENT_TwoParams(MNode, FCanBranchEvent, typename ElementType&, bool&)
FCanBranchEvent CanBranchEvent;

I have the event bound using the following:

node->OnCanBranch().AddRaw(this, &MWorldOctreeElement::CanBranch);

Note: node is a pointer to an instance of the class and OnCanBranch() just returns a reference to CanBranchEvent.

The event is only ever called from another thread using:

CanBranchEvent.Broadcast(Element, can_branch);

The issue that I am having is that when ever calling this and other events from a thread that is not the game thread, my game thread takes a huge performance hit. Even though, I am calling from a separate thread, are my bound functions running on the game thread?

[Mattlauk]

After a few hours of debugging, I’ve figured out that if an event id broadcast from another thread the game thread with wait for the events to finish processing. I placed a break point close to the end of the function called by the event. Once the break point was hit, I switched over to the main thread and discovered that it’s just chilling in the following function: