Crash: sometimes will crash at this point, what can i do to find the root cause

[LivenChief]

[mjarvis]

Looking at the left side, it appears this is breaking on a background thread. ReSwift does not support multi-threading and will crash if you dispatch an actions from multiple threads. Take a look at the dispatch you're making an ensure its sent on the thread you're using ReSwift (usually main)

[LivenChief]

our structure：
viewController contains some featureView, such as featureView1, featureView2, featureView3.
each featureView will subscribe store when viewController viewDidLoad, and will dispatch som action sometimes too.
is it right?

[mjarvis]

Yes, this is fine.

[mjarvis]

Sorry, mistakenly closed and submitted my comment prematurely. Subscribing and dispatching in viewDidLoad sounds fine, yes.

[LivenChief]

It is difficult to avoid dispatching on different threads, because a thunk call api response may be dispatched in one of the featureViews, then we will dispatch response date in network response threads(usually not main)
can i solve in this way?

[LivenChief]

Another thing that block me is when to clear the data on the store？ I hope you can give me some advice， thank you very much

[mjarvis]

I would not recommend async'ing all function calls, there are many cases where you want dispatches to happen synchronously (eg user input). You should instead consider each thunk and ensure its asyncing to the main thread itself before dispatch(foo) if needed.

[DivineDominion]

@LivenChief +1 to what @mjarvis said.

This is still a good rule of thumb:

I start with the ideal assumption that everything will run on the main thread.
https://inessential.com/2014/03/08/api_design_the_main_thread_and_queues

Your goal then would be to make it so that everything that dispatches to a BG queue eventually ensures that the main queue is reached again.

Sprinkle in some assert(Thread.isMainThread) (via https://inessential.com/2020/01/20/on_replacing_operationqueue) and you can detect where your assumption about being on the main thread is violated, and by whom.

[LivenChief]

thank you very much，guys

[LivenChief]

Hi @DivineDominion @mjarvis
mine viewController contains many featureView, each featureView will subscribe store, I want to last receive the store data featureView to clear store data nil when i dispatch action change store data, so that i can keep store data more clear not bloated. but i found that subscriptions is an unordered collection Set
How i can know which subscription is the last one receive data?

[DivineDominion]

@LivenChief Sorry, I can only 80% follow :)

If you want to make sure that N subviews receive a state update in a specific order, don't subscribe each of these. Instead, subscribe a common ancestor and make it forward the relevant information to its child views. (In technical terms, it's up to you to express the intent of updating views in a specific seauence.)

If I'm getting this wrong, can you share a pseudo code example?