'Manipulating list in thread safe way

I've a set of listeners that class can be accessed to by classes to add themselves or remove themselves from the set.

private val set = mutableSetOf()

fun register(listener: Listener) {
    set.add(listener)
}

fun unregister(listener: Listener) {
    set.remove(listener)
}

private fun notifyListeners() {
   set.foreach{
      it.notify()
   }
}

If a class removes itself from the set while notifyListener() is iterating over the set, it can result in a race condition. What's the best way to avoid race condition? How can this code be improved?

androidmultithreadingkotlincollectionsrace-condition


Solution 1:[1]

I'd suggest simply using CopyOnWriteArrayList and only resorting to a custom synchronization implementation if performance is unsatisfactory (the documentation mentions that making copies of data on every mutation can be costly).

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Solution Source
Solution 1 Egor

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